PHYSIOLOGICAL EVALUATION OF APANA VATA Dissertation submitted to the Kannur University, Kerala, In partial fulfillment of the regulations for the award of the degree of DOCTOR OF MEDICINE (Ay) In Kriyasareera By Dr. EBEY ABRAHAM Under the Supervision of Dr. ANNY YOHANNAN. M.D. (Ay) Professor & H.O.D., Department of Kriyasareera Govt. Ayurveda College ThiruvananthapuramDEPARTMENT OF POST GRADUATE STUDIES IN KRIYASAREERA GOVERNMENT AYURVEDA COLLEGE, KANNUR – 670503 2007
DEPARTMENT OF POST GRADUATE STUDIES IN KRIYASAREERA GOVERNMENT AYURVEDA COLLEGE, KANNUR – 670503 CERTIFICATEThis is to certify that the dissertation entitled “PHYSIOLOGICAL EVALUATIONOF APANAVATA” is the record of research work conducted byDr. EBEY ABRAHAM, under the supervision and guidance of Dr, AnnyYohannan, professor and H.O.D, Dept. of Kriyasareera, Govt. AyurvedaCollege, Thiruvananthapuram.This title has not been awarded Degree, Diploma, Associateship, Fellowship orsimilar honours previously. I strongly recommend and forward the same forbeing submitted for evaluation to the adjudicators.Place:Date: Dr. Anjali Sivaram. MD (Ay), Reader & H.O.D., Dept. of Kriyasareera, Govt.Ayurveda College, Pariyaram, kannur.
DECLARATIONI hereby declare that this dissertation work entitled “PHYSIOLOGICALEVALUATION OF APANA VATA” is a bonafide work of research done by meunder the guidance of Dr. Anny Yohannan, Professor & H.O.D, Departmentof Kriyasareera, Govt. Ayurveda College, Thiruvananthapuram, and no part ofthis work have been presented earlier for any degree or similar title of any otheruniversity.Pariyaram, Dr. Ebey Abraham.Date
Acknowledgement It is a subject of great dispensation from the God Almighty for me towork under the competent and highly unrivaled guidance of Dr. Anny Yohannan,Head of the department, Department of Kriyasareera, Govt. Ayurveda College,Thiruvananthapuram, who make wider my capabilities and always gave megenerous freedom. Her critical judgments, plentiful wisdom andencouragements directed my abilities kept me in the right way and ultimatelytowards the attainment of this goal. My deep sense of gratification owes for my Father late M.T.Abraham andMother Rosamma Abraham, who are the architects of my career. The mores,restraint and determination, which I could take in, are solely because oftheir meticulous nurture and strong moral support. Also I am obliged to mymuch-loved wife, Dr. Babitha Catherine Jose, my brothers and sisters fortheir untiring support and care right through my life. My deep gratitude to Dr. K.T. George, Principal. Dr. T. Sivadas, VicePrincipal, Govt. Ayuveda College, Pariyaram, their accuracy and commitmenttowards research has helped me a lot from the very beginning to the end ofthis work. I am very grateful to Dr. Anjali Sivaram, Reader and H.O.D., Dept ofKriyasareera, Govt. Ayurveda College, Kannur for her timely help andsuggestions from the beginning to the end. I also extend my sincere thanksto Dr. Prasanth Attupuram and Dr. Seena, Teachers, Dept of Kriyasareera,Govt. Ayurveda College, Kannur for their timely help and suggestions. I herewith solicit my special gratitude to Dr. Anandalakshmy, for hervaluable suggestion and judicious helps. It is beyond the reach of my language to inscribe the profoundgratitude, I feel for my department staff, colleagues and patients, who were
always with me to discuss various theoretical as well as practical issuesconfronted during the study. I am herewith soliciting gratitude to Dr. John K. George, Professorand H.O.D., Dept of Roganidana, Govt Ayurveda College, Pariyaram, and Dr,Ajithkumar K.N., Reader, Dept of Roganidana, for valuable suggestions andhelps. I also extend my sincere thanks to my batch mates Dr. Sudhagopal, Dr.Pradeep, Dr. Vibhu, Dr, Namrata and my friends Dr. Pramod, Dr. Sijin, Dr.Vidya Menon, Dr. Viswanath, Dr. Yogesh, Dr. Sambhu, Dr. Nandkumar, Dr.Ajitha, Dr. Rajitha, Dr. Bindu, Dr. Aravind, Dr. Prasanth, also for myseniors Dr. Abhilash and Dr. Bindu Mary Mathew, Dr. Surama, Dr. Anupama andother P.G scholars of various Ayurveda Colleges for being there whenever Iwas in need them the most and for their constant support and encouragement. I am very much thankful to the staff of library and office staffs fortheir kind co-operation, which was very much necessary for the successfulcompletion of this work, with special expression of my gratitude towardsSmt. Shyma and Mr. Suresh, staffs, Dept of Kriyasareera for their assistancein the laboratory. It is my great pleasure to acknowledge my indebtedness to all thecolleagues and teachers of Govt. Ayurveda College, Kannur, Pariyaram, Keralafor their encouragement and inspiration. Dr. Ebey Abraham
ContentsList of AbbreviationsList of TablesList of Charts and Diagrams IntroductionI – Literary Review Chapter 1- CONCEPTUAL STUDY – VATA DOSHA Chapter 2- APANA VATA Chapter 3- APANA VAIGUNYAII – Clinical Study Chapter 1- MATERIALS AND METHODS Chapter 2- OBSERVATIONS AND ANALYSISIII - DiscussionIV - SummaryV - Conclusion Bibliography Appendix- Pro forma
List of abbreviations 1. A. H : Astanga Hridaya 2. A. S : Astanga Sangraha 3. A. K : Amarakosha 4. B. P : Bhava Prakasha 5. Ch. : Charaka Samhita 6. M.N : Madhava Nidana 7. S.S : Sharangadhara Samhita 8. Su. : Susruta Samhita 9. Vag. : Vagbhata 10. Chi : Chikitsa sthana 11. Ind : Indriya sthana 12. Ka : Kalpa sthana 13. Ma.Kha : Madhyama Khanda 14. Nid. : Nidana sthana 15. Poo.Kha : Poorva Khanda 16. Sa : Shareera sthana 17. Sid : Siddhi sthana 18. Soo : Sootra sthana 19. Utt : Uttara tantra 20. Vim : Vimana sthana
List of Tables1. 1. Physical properties of vata – View of different classics.2. 1. Dharana karma of five divisions of vata3. 1. Reference of apana vaigunya in different contexts.3. 2. Hetus of vata vaigunya3. 3. Hetus for apana vata vaigunya3. 4. Lakshanas of apana vaigunya3. 5. Guna and karmas of apana vata5. 1. Distribution according to Age group5. 2. Distribution according to sex5. 3. Distribution according to occupation5. 4. Distribution according to the place of residence5. 5. Distribution according to religion5. 6. Distribution according to economic status5. 7. Distribution according to food habits5. 8. Distribution according to food fiber intake5. 9. Distribution according food qualities5. 10. Distribution according food quantities5. 11. Distribution according rasa intake5. 12. Distribution according nature of sleep5. 13. Distribution according to type of profession5. 14. Distribution according to addiction for Smoking
5. 15. Distribution according to alcohol consumption5. 16. Distribution according to tobacco chewing5. 17. Distribution according to tea/coffee taking habits5. 18. Distribution according to stress and strain5. 19. Distribution according to excess anger5. 20. Distribution according vegarodha – kshut5. 21. Distribution according vegarodha – trit5. 22. Distribution according vegarodha – shakrit5. 23. Distribution according vegarodha – mootra5. 24. Distribution according to indigestion5. 25. Distribution according to tastelessness5. 26. Distribution according to incomplete evacuation5. 27. Distribution according to change in bowel habit5. 28. Distribution according to fullness of stomach5. 29. Distribution according to dry stool5. 30. Total score obtained5. 31. Distribution according to slimy stool5. 32. Distribution according to bloody stool5. 33. Distribution according to undigested food in the feces5. 34. Distribution according to urinary problems5. 35. Distribution according to menstrual problems5. 36. Distribution according to male sexual problems5. 37. Distribution according to female sexual problems5. 38. Distribution according to Presence of kateegraha
5. 39. Distribution according to agnibala5. 40. Distribution according to prakriti5. 41. Analysis of the relation of age with dry stool.5. 42. Analysis of the relation of occupation with dry stool.5. 43. Analysis of the relation of rasa with dry stool.5. 44. Analysis of the relation of mental stress with dry stool.5. 45. Analysis of the relation of suppression of hunger with dry stool.5. 46. Analysis of the relation of suppression of bowels with dry stool.5. 47. Analysis of the Incidence of kateegraha with dry stool. In both groups5. 48. Analysis of the effect of food in both groups5. 49. Analysis of the effect of food fibers in both groups5. 50. Analysis of the effect of mental stress in both groups5. 51. Analysis of the effect of suppression of bowel in both groups5. 52. Cross tabulation of dry stool in different prakruti
List of Charts & Diagrams3. 1 Absorptive and storage functions of large intestine3. 2 Parasympathetic mechanism for defecation reflex3. 3 Neural arc of micturition3. 4 Erectile tissue of the penis3. 5 Phases of Menstruation3. 6 Peristalsis5. 1 Distribution according to age group5. 2. Distribution according to sex5. 3. Distribution according to occupation5. 4. Distribution according to the place of residence5. 5. Distribution according to religion5. 6. Distribution according to economic status5. 7. Distribution according to food habits5. 8. Distribution according to food fiber intake5. 9. Distribution according food qualities5. 10. Distribution according food quantities5. 11. Distribution according rasa intake5. 12. Distribution according nature of sleep5. 13. Distribution according to type of profession
5. 14. Distribution according to addiction for Smoking5. 15. Distribution according to alcohol consumption5. 16. Distribution according to tobacco chewing5. 17. Distribution according to tea/coffee taking habits5. 18. Distribution according to stress and strain5. 19. Distribution according to excess anger5. 20. Distribution according vegarodha – shut5. 21. Distribution according vegarodha – trit5. 22. Distribution according vegarodha – shakrit5. 23. Distribution according vegarodha – mootra5. 24. Distribution according to indigestion5. 25. Distribution according to tastelessness5. 26. Distribution according to incomplete evacuation5. 27. Distribution according to change in bowel habit5. 28. Distribution according to fullness of stomach5. 29. Distribution according to dry stool5. 30. Total score obtained5. 31. Distribution according to slimy stool5. 32. Distribution according to bloody stool5. 33. Distribution according to undigested food in the feces5. 34. Distribution according to urinary problems5. 35. Distribution according to menstrual problems5. 36. Distribution according to male sexual problems5. 37. Distribution according to female sexual problems
5. 38. Distribution according to presence of kateegraha5. 39. Distribution according to agnibala5. 40. Distribution according to prakruti
IntroductionT he fundamental principles of Ayurveda are panchabhootha and tridoshatheories. The objective of this ancient science is to attain health in totality,physically, mentally and spiritually, to attain the purushartha. This greatscience of life explains the regimen one has to follow, which favors the wellbeing of every creature. Ayurveda emphasises the well known principle"prevention is better than cure" fulfilling all its meaning. The goal of physiology is to explain the physical and chemical factorsthat are responsible for the origin, development, and progression of life. Eachtype of life, from the simple virus to the largest tree or the complicated humanbeing, has its own functional characteristics. In human physiology, we attemptto explain the specific characteristics and mechanisms of the human body thatmake it a living being. According to Ayurveda, a living body can function normally, only whendoshas, dhatus and malas are in a state of equilibrium. Tridohsas, sapthadhatusand trimalas constitute the basis of the physiological and pathological doctrineof Ayurveda. The tridoshas have been identified as basic functional units ofevery living structure, the cells, tissues, organs and systems. On the normal ordisturbed equilibrium, these three doshas determine health and ill health
respectively. Tridoshas exhibit patho-physiological changes in the living bodywhen their state of equilibrium is altered. In undisturbed condition ofequilibrium, they contribute to the healthy state, preservation and maintenanceof life. Among the tridoshas, the vata holds the foremost position as it is themost significant factor both for maintaining proper body health as well as forthe causation of diseases. Vitiation of vata dosha is the aetiology for manypathological states of the body and mind. As this is very important, Charakaeven has devoted a special chapter for the description of vata, the"Vatakalakaleeya Adhayaya". Vata is omnipresent, but it has variation in itsgunas and karmas according to its special sthanas, i.e. as per an organ orsystem in which it is present. Hence it is divided into five. In our classics, the fractionate analysis of vata dosha has been narratedwell. In this fraction, Prana vata places the foremost position with the specificfunctions of controlling body characteristics like intelligence, mental activitiesand controls respiratory system. The Udana controls the phonation, energy,bodily strength and the retention of memory. Samana mainly has control overthe digestive function, aids the Pachaka pitta to perform in a right way. Yetanother vata, termed Vyana vata undertakes overall control over the body. The last but not the least is Apana vata, which is significant in thisstudy. Acharyas mention that this part controls the emission of sukla, arthava,
sakrith, mootra, and grarbha and its seats are pakwashaya, stoolanthra, gudha,shroni, vasthi, medhram, ooru. Acharyas considered that pakwashaya is a main sthana for vata.Through this pakwashaya, all the above mentioned subtypes of vata attain balaand hence pakwashaya is the moola of vata. Elimination of sthoola malasthrough guda is essential for the maintenance of the sareera ni-rogavastha.Any vitiation in the normal state of apana vata or the pakwashaya leads to thedisruption of the normal physiological functions of the other subdivisions ofvata. Apana vata is the one of the important concept in Ayurveda, and it isdirectly related with the occurrence of many diseases in the pelvic areas. Theincidences of these diseases are increasing in the present day today life due tofaulty lifestyle and unhealthy food habit. Still only few studies have beenconducted involving these factors. This state of affairs urged me to conduct astudy regarding the causes of apana vata vitiation. This study, I hope not onlyhighlights the physiological importance of apana vata but also draws attentionto the pathophysiological aspects of the same. In the modern era, due to irregular and improper habits of ahara, viharaalong with the suppression of natural urges, the percentage of apana vaigunyajanya vyadhees are increasing by leaps and bounds. The effect of apana vatavitiation can very well be visualized from the simple discomfort likemalabandha to the most complicated and disheartening conditions like klaibya.
Based on these observations, aim of this study is to disentangle theunrevealed concept of apana vata and to evaluate the role of it in maintainingthe homeostasis. To affirm this statement, the physiological aspects related with apanavata territory are narrated in this work. In addition, the clinical conditionsdirectly or indirectly related with apana vata vaigunya have been illustrated.Special emphasis has been given to the most common effect of apana vatavaigunya, the malabandha, and a clinical survey has been conductedconcerning its aetiology. A reference existing in the eighth chapter of Prasnopanisath states that;the God of apana vata and the God of pureesha, holds each other and carrytheir normal functions. Vitiation in the parthivatwa (pancha bhautikatwa) ofpureesha of apana vata leads to the apana vaigunya. Though lots of the research studies have been carried out in relation tothe vatavyadhi or pureeshavaha srotas, this study is the first of its kind toreveal the physiological and patho-physiolgical aspect of apana vata. Hencethis study has its own significance to revalidate this aspect.Aim and objects 1) To evaluate the concept of apana vata in better perspective. 2) Comparative study of functions of apana vata with the similar physiological functions described in modern medical science.
3) Take an illustration of the pathophysiologies of apana vata with special emphasis on malabandha.Alternate hypothesis: Apana vata is the controlling system concerned withreproductive, ano-rectal, urinary, and pelvic functions.Null hypothesis: Apana vata is not the controlling system concerned withreproductive, ano-rectal, urinary, and pelvic functions.Study in a nutshell Ø This explorative study has been carried out in the Govt. Ayurveda College/Hospital, Pariyaram, Kannur, Kerala, under the department of Kriyasareera. Ø The total duration of the study is 18 months. Ø Normal healthy individuals between the age group 20-50 years were selected for the first assessment and Individuals suffering from malabandha, within the age group 20–50 years were selected for the second assessment. Ø Statistical analysis, observation and interpretation are made, before making the conclusion of the study.Frame of this workUnit-1 IntroductionUnit-2 Literal Abstraction • Contains literary collection on Conceptual study of vata dosha, apana vata physiology and apana vata pathophysiology.
Unit-3 Clinical Research • Contain Research Methodology, Observations and Analysis.Unit-4 Discussion • Contain Discussion on Literal Abstraction and on Clinical Research.Unit-5 SummaryUnit-6 Conclusion Addendum
Conceptual study – Vata dosha Ayurveda is a monumental contribution of India to the world. As thename implies, it is an organized body of knowledge of healthy living. Itrepresents a well-codified human care system and speaks of the art and scienceof health and healing. Ayurveda is the science of life, which explains theknowledge of various strategies to follow in order to make a healthy living. Health is defined as a state wherein the dynamic balance of doshas,dhatus and malas is maintained, the metabolism is at optimum level and soul,mind and sense organs assume sublime position. This definition fully agreeswith the integral vision of health envisaged by W.H.O.; the former has anadditional dimension of sound spirituality. The living body can functionnormally only when its doshas, dhatus, malas and agni are in a state ofequilibrium.1 Tridoshas are the fundamental constituents of the body and play a vitalrole in the maintenance of overall health through a life in conformity with lawsof nature. When these factors become either augmented or diminished, eitherpartially or totally, the body may become either sick or dead2,3. Diseases are the manifestations of perturbations in the equilibrium ofbody constituents including doshas. The vitiated doshas are the prime causativefactor for a disease. Because they are the only causative factors for the vitiationof other bodily elements like dhatus. Consequently, doshas are the main
causative factor for initiation of a disease, next to agni. Out of these tridoshaseverywhere and in every aspects, supreme role has been given to the vatadosha4. In the normal state, vata in consequence of its quality of motivationkeeps the kapha, pitta, dhatus and malas in action, give them proper directionfor functioning, which are incapable of independent motion. However, in caseof disease conditions, the direction of vata becomes ill defined and thuscausing aetio-pathologies of different diseases. Vata is the cause for all types of patho-physiological functions of pittaand kapha. The line of treatment too, demands pacification of vata, in additionof these two factors because it is the prime aetiological factor. There is unique importance of vata, in physiological, aetiological andmanagement aspects. Vata has been described as ayu, balam and dhatha also.These all explanations support the significance of vata among the tridoshas.Among tridoshas vata dosha pertain a superior position due to its motivatingquality.VATA DOSHA Combination of panchatanmatras in various proportions and modes giveorigin to the five mahabhoothas. The vayu mahabhootha is produced by thecombination of sabda tanmatra with sparsha tanmatra and with the assistanceof akasha bhoota. "Akashad vayuh |"
Vayu has been originated from akasha and is of two types: nitya andanitya.Nitya vayu is of infinitesimal in nature hence it is never-ending and anitya vayuis again divided into three.(1) Vayaveeya sareera : Exists in vayu loka(2) Vayaveeya indriya : Twak(3) Vayaveeya Vishaya : Movements of objects, vata in body etc.Structures derived out of vata are the organs of touch and hearing.Grammatical derivation of the word vata :The term vata is derived from, (i) The application of tan pratyaya (Suffix) and expelling n pratyaya later to the Sanskrit verb root va which means Gati Gandhanayoh 5 (ii) The application of krt pratyaya to the Verb root va which again means the same as above, vatiti vata, the term vata is derived. 6The verb root va means gati and gandhana. The meaning of gati is as follows.(1) Prapthi (to acquire, to attain)(2) Jnana (to know, to sense.)gati prapti jnana mithyarthantharam (Panini) "Roopa rahita sparsavan vayu" Right from the above description, it is implicit that the term vata itselfconveys its role as a receptor as well as stimulator. Hence, it can be said that
vata is the biological force that can be aware of and arouse all the activities in aliving body. All the physical movement in the body is expressed by thecontractions and relaxations of the muscles i.e. the motor function. Here thesecretary function is also included and the knowledge is got hold from thereception through the five sensory organs. The meanings of the word gati aremotion, moving and going. The meanings of the gandhana are intimation,information and hint. Therefore it is clear that this somatic factor vata has twomain functions i.e. cheshta and jnana.Vata - the most important among tridoshas As we discussed earlier, there is references on vayu in the chapter ofVata kalakaleeya of sootrasthana of Charaka Samhita. In this chapter, acomparison has been brought forth between the lokavayu - physical vayu andsareeravata - biological vata. Both of these are derived from the fivemahabhootas, with the predominance of akasha and vayu bhootas, with theresult that both are invisible. Consequently, their presence can be deduced andunsurprising only by their actions and functions. Even though the tridoshas are uniformly significant and indispensable inthe body, reciprocally harmonizing one another, vata - the most importantamong tridoshas - appears to be the principal motive force in the body7Vata – its importance.These points pressure on the importance of vata among tridoshas.1. Vata is the grounds of all cheshta takes place in the living body.
2. The organic vata is not only transportable but also capable of keeping pitta, kapha, dhatus and malas in motion83. Acharya Bhela affirms that life exists as long as vata lasts in the body.4. Vagbhata’s states that vata is capable of hasty action. Its have high potency, power over the functions of the body, capable to vitiate other factors and has self-determining movement9.Several synonyms like pavana, anila, sameera, maruta, are applicable forsareera vata also.Due to the three important properties, vata is entirely different from otherdoshas. • Asamgahata (intangible) • Anavasthita (Instable) • Anasadhya (Inaccesible) "Avyakto Vyakta Karmacha |" (Su. U. 21) Two elements, vayu and akasha constitute vata. Hence, it is supersensuous, invisible, so it cannot be perceived, but it is tactile and can berecognized by its functions. Pitta and kapha have appendages and relativelycompact in nature. On the contrary, vata is incorporeal (Avayava samghatharahitha). It can be termed as rarified in nature. The vata is anavasthita too.These two properties are due to its bhauthika composition i.e. akasha and vayupredominance10. Akasha and vayu are incorporeal (amoortha). Chalatwa andaprateghatatwa are characteristics of vayu and akasha perceptible by the tactilesense organ11. According to Tarka samgraha, vayu is devoid of shape (roopa
rahita) and possess sensibility to touch (sparshawan). The biological vata isself originated (swayambhoo), Subtle (sooksma) and all pervasive(sarvagatha). Anavasthita is due to chala guna of vata. In another terminology likeseeghrawat (Swift movement)12, ashukari (instantaneous action), muhuschari(Rhythmic movement)13, it points out the fundamental quality of rajas. Owing to its incorporeal nature and instability, vata is inaccessible also.It is pertaining to its functional and physical attributes, but more relevantregarding the therapeutic aspect. All these cardinal features make vata achintyaveerya and doshanam netha14. The above-mentioned three qualities indicate that vata is not a physicalmatter but a form of energy capable of conducting some physiologicalfunctions in the body.Vata- properties. Acharyas exceptionally pressure on the gunas of the vata dosha asrooksha, laghu, seeta, khara, sookshma and chala properties. Vata is welldistinguished with reference to the sloka mentioning the rookshadi gunas. Thestress on these qualities is due to • An increase in these behavior in the body indicates the increase or vitiation of vata and vice versa and
• The significance of the snigdhadi gunas which are opposite of rookshadi which lighten the vitiated vata. Consequently, the knowledge of these gunas will facilitate anappropriate impend in the management of a vataroga. However, these do notrepresent the behavior of vata in its physiological form/state. Thus, the moreimportant qualities of vata, which explain its nature more correctly, areexpressed here.Intangibility of vata dosha It the most significant peculiarity of vata15. It is confirmed asamoorthatwa16 indicating the nonappearance of a corporal form like pitta andkapha. This quality of vata is probably due to the predominant constituentelements, akasha and vayu. The vata cannot be apparent with the sensory organs whose things areoriginated from the remaining bhoothas i.e. agni, ap and pridhwi,representative that vata does not possess colour, taste and odour. Vata can beexperienced by the sensory organ of skin. In vision of its intangibility, the otherindividuality can be apparent only through inferential logic on the facts ofsurveillance and by the actions/functions it performs17.The property of instability This is the subsequently important value of vata i.e., instability, which isalso qualified as chalatwa – mobility18. Vata moves very quickly19 vata is not
only changeable but is also capable of dislodging pitta, kapha, dhatus andmalas, which are incompetent of autonomous movement20. This qualityindicates the capacity of vata to exert influence on another dosha and the body. On the subject of its physiological state, this quality of chalatwa isdirectional in nature. In the cheshta vaha srotases, vata moves towards thekarmendriyas from the buddhi and manas, whereas in the sanjavaha srotases,the movement is towards the manas from the sense organs. For themaintenance of physiological function, vata should have movement withoutany hindrance21. This indicates that obstruction to its movement will bringabout a pathological condition. Due to its hasty movement, vata isinstantaneous in action and radiates through the body in repetitive currents.22Swayambhoo nature of vata Acharya Susruta states that vata is svayambhu23. This self-existence alsointerpreted as self-originated. For executing the functions of gati andgandhana, vata may be self-originated and as well self- propagating in buddhi.All the three qualities indicate that vata is not a corporeal matter but a form offorce talented in conducting some physiological functions in the body. In viewof this fact, Charaka has not mentioned the normal quantity of vata in the body.Supplementary qualities of vata Theses qualities are enumerated with possible descriptions that areRooksha:- This is the contradictory of the snigdha feature, Seeta:- Normallythis seeta or ushna feature refers to the deed of the matter in the body. Laghu:-
this feature is also due to the principal akasha and vayu bhoothas andcontributes to the speedy progress of vata. Daruna:- the interpretation ofChakrapani as chalatwa - mobility, however according to others it is hardness,kadhinya- indicating that vata can make a substance hard by drying it up25.This seems to be a better explanation. This indicates only the action of vata butnot its quality. The chalatwa quality has already been conversed over. Khara-the rough and friction giving nature of vata. Sookshma :- This is the facility tobreak through the negligible channels of the body26. This quality is due to thehigh proportion of akasha element. At the time, there is vitiation of vata in thebody, an augment in these rookshadi gunas is perceived and the application ofthe snigdhadi gunas results in the alleviation of the vitiated vata. Therefore,the vata is commonly implicit to acquire these rookshadi gunas. Another significant observation, which leads to the deduction regardingthe qualities of vata, is related to the influence of ahara, oushadha and vihara.The constant use of the ahara and oushadha possessing opposite gunas i.e.snigdhadi, is associated with the alleviation of the signs and symptoms causedby the vitiated vata and restoration to its normal states of functioning. Thisobservation leads to the conclusion that the character of sareera vata mustcomprise of the former group viz. rookshadi gunas. Even supposing the vata does not have direct contacts with its frustratingand alleviating factors, still such factors are directly connected with the bodyand so the vata moving within the body has indirect contacts with them. Thus,
it is provoked or alleviated depending on its contacts with homologous orheterologous character in that order28. There is difference of opinion regarding the number and nature ofphysical properties of vata in different Ayurvedic classics and in differentcontexts of the same classic too; they are.Table 1. 1. Physical properties of vata – View of different classics. Sr. Physical Ca. Su. Ca. Su. Ca. Vi. 8/98 Su. Ni. 1/7 Ah. Su. No. Properties 1/59 12/4 A. S. Su. 1 Rooksha + + + + + 2 Seeta + + + + + 3 Laghu + + + + + 4 Khara + + - + + 5 Visada + + + - - 6 Chala + - + - + 7 Sookshma + - - - + 8 Daruna - + - - - 9 Parusa - - + - - 10 Seeghra - - + - - 11 Bahu - - + - - Total 11 7 6 9 4 6 All the Acharyas have opined that vata is having rooksha, seeta, laghuand khara gunas. Chala guna has been also mentioned by all Acharyas exceptSusruta. However, Susruta in the same context where properties areenumerated, explained that vata is tiryaggaha29 this clearly indicates thechalatwa guna of vata. It is interesting to note that Charaka has omitted chalaguna in the Vatakala kaleeya Adhyaya30.
Instead of which, the Guna daruna has been added. Gangadharaobserves in this context as chala as well as sookshma are intentionally omittedas they are mentioned earlier as anavastitha and asamghata31. But Cakrapaniclarifies this point by interpreting it in two ways. The term daruna byimplication may mean chalatwa, alternately it may mean kathinyam in thecontext of the soshana swabhava of vata32. The second interpretation seems more acceptable. Because daruna gunaitself is sufficient to cause chalatwa. As daruna guna is characterized bysoshana swabhava, it can create the padartha laghu by drying up the apyaguna, thus by increasing vayu and akasha, by an indirect way, daruna guna ispossible to create extra avakasha. However it may be conceived that chalaguna is manifested when laghutwa and avakasha are increased. Another important Guna is rooksha. Rooksha Guna causes snehadi gunasoonyatha (lack of qualities like unctuousness). Snehadi guna soonyathaproduces riktata33 and the aggravated vata causes higher rate of chaltava34.This rooksha guna has more importance in pathological as well asphysiological state of chalatwa of vata. Seetaguna is also one of the important guna of vata. Seeta guna vruddhiresults in stambhana (reduction of mobility). Increase in laghu guna causesincrease in chalatwa or mobility due to its panchabhautika composition35. Cakrapani commented as vata is the controller of basic technology ofthe body machine, which includes basic characteristics of any living body and
exclusive characteristics for only human being. Vata, being first of thecontrolling systems of the body, monitors and co-ordinates all the vital lifeprocesses.Another property - yogavahi A matter when related with other substances projects their dispositionalso without losing its own, is known as yogavahi36. When vata induces theother two somatic humors into motion, it identifies itself with them. Whenallied with pitta, the vata creates a feeling of hotness and while related withkapha, a reaction of frostiness37. The actual function of skin is the awareness ofthe consciousness of touch, for which also vata is the mediator.The seats of vata The general locations/seats in the equilibrated state of vata pitta andkapha are the lower, middle and upper portions of the body respectively38,although it is stated that they pass through the entire body. However, certainspecific parts/organs of the body have been stated to be the seats of the somatichumors. The following are the seats of vata39.Pureeshadhana:-. Pureeshadhana should be considered as that portion of theintestines wherein is located the pureeshadhara kala. This pureeshadhana alsoincludes the guda, which is mentioned by Susruta as the seat of vata.Vasthi:- it is still in a debate that whether vasthi is mootrashaya – (urinarybladder) or vasthimarma - which possibly includes the kidneys also.Nevertheless, together may be measured as the seats of vata.
Kati or shroni:- Pelvis – The lumbo-sacral region and where the spine meetsthe pelvis bone. Numerous diseased conditions due to the vitiation of apanavata are affected in these areas.Sakthini:- ThighsPada:- FeetAsthi:- BonesPakwashaya:- It is the part of small intestines where the digestion of theingested food is completed and the sara is separated from kitta. According tomodern science, it can be considered as the areas of small intestine.Ears and skin - The awareness by these sensory organs is from side to sidechanges in the air vibration. In the latter, the insight is also by straight touchwith the article. All the Brihattrayis generally affirmed that pakwashaya is the particular/chief seat of vata. It may be noticed from the above that apart from for asthiand two sensory organs, all are the sites of apana vata, one of the five varietiesof vata and the spaces of the other four varieties have not been mentioned. Concerning the chief behaviors of vata viz. amoortatwa,anavasthitatwa, chalatwa, and swayambhoo, attached with its main task of gatiand gandhana as resultant by its meaning, the main seat of vata has to be wellthought-out as siras or rather the brain i.e. central nervous system. There areother points to institute this fact.
As per Charaka, the siras representing the prime place involving thevital organs of the body and it is the seat of the vital centers and all the sensefaculties40. The description also indicates that the five indriyabuddhys thatdecisively perceive the five senses are located in siras - that is mastishka. Therea reference in Adharvaveda that vata is located in the superior portion ofmastishka41. The manas which is enclosed between siras and talu42 isproscribed by vata. Here the word siras has to be implicit as vertex of the skulland talu is palate43. Primary importance among the seat of vata is goes to pakwashaya44. Itis also affirmed by Vagbhata that koshta - presently the pakwashaya - is theplace wherein the five varieties of vata is generated and maintained45.The role of vata in physiological functions The role of the doshas in the body are of two types physiologicalfunctions (prakruta kriya) and pathological functions (vaikruta kriya).Chakrapani put in plain words that It is not possible to itemize all thequalities/actions of the vata. Only a few have therefore been explained. Someof these can be established through straight awareness e.g. speech; a few bysupposition e.g. mental activities; a little on the basis of scriptural evidence e.g. 46the shape and dimension of the embryo . The typical functions of vata have already been indicated by itsdefinition viz. gati and gandhana. Including the detailed explanation of thesetwo functions, the other normal functions of vata are47; it is the designer of
every kind of deeds in the body. It is of three types: speech, events of mindand proceedings of the body. All the visible physical movements including verbal communication areeffected by the tightening and relaxation of the muscles. Vata causes allactivities by motivating the muscles for the required tightening and relaxationsthrough the vata vaha srotases. This is the motor effect of vata. The act of respiration - ucchwasa and niswasa - the circulation of dhatuslike rasa and rakta and the movements of the koshta are also the motorfunctions conducted by the vata. Even though it is stated that buddhi directs acreature to verbalize or do something48. The path of the buddhi is sending outto the target organs through the intermediate of vata. Vata is particularly affirmed to be connected to the initiation of touchand sound. This is affirmed with the words of Gangadhara that the reason ofsound and touch perception within the body is vata and not akasha. Eventhough the basis grounds of sound is akasha, the full expression of thisperception to be apparent by the ear is not however owing to it. It is the vata,confidentially linked with svanayantra that makes the apparent sound, whichcan be heard by a living organism. It is stated that vayu is tanthra yanthra dhara. Tanthram is the body andyanthram denotes the engine along with its component viz. denotes the angasof living body, the siras, snayus49 etc. It is therefore clear that vata is the
supporter or protractor of both the structures and their functions in the bodyand maintains them in good order. It is the sensory information from various types of receptors that is usedto conclude both static situation and the balancing of the body during motion.These comprise of widespread sensory endings in the joint capsules andligaments, the receptors in the skin and deep tissues near the joints andprobably also the muscle spindles that sense muscle stretch. Almost certainly toindicate this particular sensation, Chakrapani mentioned joints with referenceto yanthra50. In addition, vata is the manager of the intellect and performer ofintellectual faculties. Vata restrains the manas from indulging in the unwantedsubstance and guides it towards enviable articles. The functions associated withthe emotions are also the function of vata. It stimulates the digestive fire i.e.stimulates the discharge of the digestive juices in annavaha srotas - part ofkoshtha. Yet another property that it is the regular eradicator of the wastematters from the body. It desiccates the surplus humidity of the morbid humors.Vata systematize the customary creation of the tissues in the body and bond thetissues in the proper fraction to figure the structure of the body. It is theupsetting factor for the advance of all srotases of the body. Lastly, it is thecause of the configuration of various compositions of the foetal body. The living body is the congregation of millions of microscopic cells.Vata is the triggering factor for the concurrence and conflicts of these cells.
Since it is already stated that vata is the cause of the formation of differentstructures of the foetal body and the factor for built-up the amalgamation of thedhatus, it is assumed that the sareera vata has also the capability todifferentiate the cells during their development - according to the necessity ofthe body - and accordingly the structures. For that reason, it is clear that vatain its innate state of equilibrium is accountable for all actions of the body and itin fact constitutes to standard existence of living being51. Susruta states that vata in its normal state, be in motion through itsspecific conduits helps in the proper release of its definite functions - withoutimpediment viz. the expansion and contraction - of the locomotory organs,speech and other motor functions, and also fabricates the unambiguousness andnon-illusiveness of buddhi in its functions and of sense organs52.To conclude, the overall function of vata in the body can be summarized asFunctions related to emotions The chief mental functions are utsaha and harsha, experienced either injuxtaposition with the sense organs or without conjunction. The originator andmanager of all actions in the body is the buddhi. Here the broadcast of vatathrough the manovaha srotases is also important and crucial for expressingthese functions. In addition, be in command of the manas from indulging inadverse items and direct it towards pleasing things. Vata shuts down the
pathways between the manas with disagreeable things and open up thepathways towards the wanted one.Motor actions It is affirmed that sareera vata is the creator and architect of the bio-motor functions, these are activity of the skeletal muscles i.e. intendedmovement of the body, action of the involuntary musculature like heart,intestines, muscle fibers present in the blood vessels and also the respiratorymuscles, which are both voluntary and involuntary, and secretary functions.Sensory functions Vata stimulates all sensations. The information about the article fromthe sensory organ is conveyed to the mind and intellect for definiteinterpretation. The receptive sense of the thing by the sense organ is alteredinto the nerve impulse in the organ and then carried through the samjna vahasrotases via the manas to the indriya buddhi.Function of integration Word tanthra yanthra dhara signifies the function of integration of vata.Vata maintains the human machinery to keep it in good order. This functionincorporates the maintenance of the symmetry of the body and the sense ofmovements. The functions gati and gandhana of manas are co-ordinated andmaintained. This importance is again due to the predominant akasha and vayubhoothas, which join in the development of the sareera vata.
Synthesis, division and differentiation of dhatus Vata is the root cause for the synthesis of the dhatus from the nutrientspresent in the rasadhatu into definite structures through dhatu parinama anddhatuposhana. It addition, it regulate of the functions of the dhatus. Also, vatais the main force for the union and division of the cells of the body. It is thecause in differentiating the cells during their development, according to therequisite specialized functions.Neural control of the body The functions of vata in its five divisions related with neural control ofthe body can be summarized as, the voluntary and involuntary movements inthe body (gandhana) - this includes the secretary functions also (gati), and theintegration of the sensory and motor functions. In consideration of the above qualitative and well-designed factsregarding vata and its place being the mastishka and vatavaha nadees, thephenomenon of vata may be assumed as the phenomenon of nerve impulse.The qualities of the nerve impulse are similar to those of vata and its seat is thenervous system, which has the same functions as those of vata as stated above.As per the suggestion from Bhela53 like vata, nerve impulse also is present in aliving body only.
The jeeva paramanus are considered as sareeravayavas. The tridoshasare to be considered as present in the jeevaparamanus to control, direct andmaintain their functions in all over the body.
Apana Vata As we have already discussed, the concept of physiology, pathology,diagnosis, prognosis, medicine and therapeutics in Ayurveda are all based onthe theory of tridoshas. On the normal or disturbed equilibrium as the case maybe, tridoshas leads to health and ill health respectively. They are designated asdoshas because of their capacity to vitiate the body. In addition, theythemselves become vitiated by other factors. They are also known as dhatus asthey prop up the body in its normal states. The term dhatus means aningredient, an essential component, primary substance, a humor, the supporteretc. Although tridoshas are equally important and essential in the body, vatais considered as the prime among the three doshas as it governs the functions ofall other doshas through its chief drive force in the body. Depending upon thesignificance and intensity of action, all functions of sareera vayu may beconveniently grouped into five subdivisions with separate seats and purposes.1 These five divisions being the subdivisions of vata have the equalimportance as that of vata. In this fraction, prana vata places the foremostposition by controlling the vital body activities like respiration and highermental functions phonation, energy, bodily strength and the retaining ofmemory are under the control of udana. Samana vayu has control overdigestive function. Vyana vata undertakes overall control over the body.
Apana vayu controls the emission of sukla, arthava, sakrit, mootra, andgrarbha and its seats are shroni, vasthi, medra, and ooru. Of all, we can conclude that the fraction of sareera vata, which has aspecial tendency to move downwards, and controls the functions of lower partof body is termed as apana vata2.Grammatical Derivation of apana “Apanastu apanayati” Grammatical explanation of the word apana points to take away, tobreathe out, to expire to direct downwards etc. That means apana vata is a typeof vata which possess the function to expel out the excretory products of thebody.Location of apana vata Apana is the one among five subdivisions of the vata, and perhaps themost important among them.According to Charaka, apana vata is located in the following areas31. Two testes (vrushana) 2. Urinary bladder (vasthi)3. Penis (medhra) 4. Umbilicus (nabhi)5. Thighs (ooru) 6. Groin (vamkshana)7.Rectum (gudam) 8.Lower part of intestine (anthra)
Susruta in nidana sthana states that the exact seat of apana vata is thecapital place of vata itself i.e., in the pakwashaya - the capital for all thesubdivisions of vata4 5 Pakawadhana is the receptacle of the fully digested food . But there isno such separate receptacle for the fully digested food, since pakwashaya beinga place of digestion, contains only partly digested food which is received fromamasaya and the digestion of such food is completed in this region. Thenutrients which are the products of digestion are simultaneously absorbed fromthe intestine. Therefore, pakwadhana can only be assumed as that part of theintestine where the kitta bhaga is left at the end of the digestion, to betransformed into pureesha by the pureesha dharakala of the koshtha.Therefore, pakwadhana may be interpreted as the lower part of small intestine,colon and rectum. Apana vata is stated to move through the regions of urinary bladder,hips, penis, testes, groin and thighs6. The word apana indicates the lower mostend. The pakwashaya is declared as the most important site of vata, where invata and its five subdivisions is generated7. So the pakwashaya is the place where the materials necessary for growthand maintenance of the body are generated and absorbed, and also the mostimportant humor the “tanthra yanthra dhara” vata is generated and located.Looking towards these importance and apana in prakritha and vaikrithavasthaof vata, an effort has been made to study the apana vata in its totality.
According to Cakrapani, pureeshadhana is pakwashaya. But sinceCharaka mentioned both pureeshadhana and pakwashaya in the same sloka asseats of vata, it is clear that both are not one and the same and therefore theargument of Cakrapani is not correct. Pureeshadhana should be considered asthat portion of the intestines where in is located the pureeshadhara kala. Thispureeshadhana also includes the guda which is mentioned by Susruta as theseat of vata8.Gunas of apana vata Apana vata is having rookshadi gunas and mala mootradi vikshepanakarmas. Here the apana vata is the asraya sthana for its gunas and karmaswith samavaya sambhandha in between them, that means can not have theirown entity without each other9. Guna is the factor having samavaya sambandha with dravya with nochesta (actions) in it, but is the cause for the chesta. Here the relation betweengunas and karmas are like the cause and effect relationship. Guna is the reasonand karma is the effect of that cause. Like the samavayi relation between apanaand rookshadi guna, no such relations are between guna (rookshadi) and karma(vikshepanadi), though they have cause and effect relationship. Gunaswhenever in samyak yoga with dravya then become able to produce normalkarma. If these gunas are in ksheena or vruddhi avastha, then they are not ableto produce their normal karmas, either less or excess in that order. Apana beinga subtype of the vata, have the same guna as that of vata.
Taking into consideration of the importance of doshas, always firstpreference given to vata dosha in every context. Rooksha guna of vata and vataprudhvi, both are sneha sadhya, so always rooksha guna has given firstpreference for vata guna in every context.Rooksha guna : ‘Soshane Rookshal’10 It is the foremost guna of vata having bhautika sanghatana of vayu andagni. It is contradictory to snigdha guna. snigdha guna helps for paramanusamyoga, while opposite to snigdha, rooksha guna creates viyoga of theparamanu. If this type of viyoga between parmanus goes on, it will leads to thehrasa for that combination. rooksha guna has vata vardhaka and kapha samakaproperty.Laghu guna: Langhane Laghu It has akasha and vayu bhautika sanghatana. It supports the gati ofvayu. Heavy substances have less gati. Because of laghu guna, vayu createslightness in the sareera parmanus and apatarpana takes place. In addition,vyayama and upavasa create lightness in the body. It also helps to agni for itspachana shakti. It helps agni by making the padartha laghu for pachana. It isalso vata vardhaka and kapha samaka.Seeta guna : Stambhane Seeta’ Seeta guna has vayu and jala bhautika dominancy. Normally seeta orushna quality refers to the action of the substance in the body. It has pittasamaka and vata sleshma vardhaka properties.
Khara guna : ‘Lekhane Khara’ As per Susruta, It has teja, vayu dominancy and at the same time,according to Charaka, vayu and pruthvi predominance. It does the lekhanakarma in the body. It is next to rooksha in the body to makes the parmanuviyoga. This helps to remove unnecessary or dead tissues of the body from thebody. It has vata vardhaka quality.Sookshma guna : ‘Vivarne Sookshmal’ This quality is due to the predominance of akasha mahabhoota. It hasthe capacity to penetrate through the smallest srotases of the body.Chala guna : ‘Prerane Chala’ This guna has vayu predominance at bhautika level. It is the naturalguna of the vata which is also qualified as anavasthita (mobility). Vata movesvery quickly. This fast movement of vata is because of chala guna.Functions of Apana vata The action which has to be happened is called as karma. Here karmameans not karmakaraka but it is the kriya. The word kriya is derived from kru+ manina" pratyaya11. A padartha, residing in dravya and responsible for all samyoga andviyoga of the dravya is called as karma. Lots of lakshanas are available in theClassics for karma, but perfect one is "An action which has to be happened as
the duty without any other expectation”. In the living body, vata is dominantlyresponsible for all the normal and abnormal karmas (activity). There is no difference of opinion among the authors regarding the functionsof apana vata. They are the following12 Ø To facilitate the excretion of feces and urine, Ø Ejection of the semen, Ø To cause the menstrual flow, Ø To bear down the foetus at the time of delivery. The principal place of apana vata is the pakwashaya - a capital of vataalso. From this place, apana vata keeps control over the karmas happening inits vasti medhradi area. Being in pakwashaya, apana vata is also in connectionwith other subtypes of vata. Therefore, any qualitative or functional change inits area as well as in the other subdivision will may leads to vitiation inpakwashaya as well as apana vaigunya. So the apana vata has moreimportance in its sub division group. In addition, the place of apana vata (pakwashaya) has its ownimportance in the contest of vata. It has been stated by vagbhata that koshta,presently the pakwashaya is the place where vata and its five varieties aregenerated13. Here "Generated" means the materials necessary for maintenanceof the structural integrity and also the materials essential for maintaining thefunctional integrity are produced. In short it gives strength to the dharanakarma of the vata14.
Vata, the one among the three basic constituents of the living body hasits entity mainly because of its chala guna and it remains as such until, there isnithya sambhandha in between ayu and sareera. For this nithya sambandha,pitta provides materials from food, kapha is the material for that structure andvata creates structure from that material and hold (dharana) it. The meaning ofdharana karma is not just limited up to the word dharana. Here it has broadmeaning. From the vata, dharana karma expected to maintain the nithyasambandha in between ayu and sareera by its prakritha guna karmas. Here also dharanat dhathvaha of the saptha dhatus and that of vataalso differ. The saptha dhatus are the structural entity with the functions ofnourishment (poshana) and that of vata is in avyaktha swaroopa with thefunction of nourishment (poshana) supply. It is the basic different between thedharana karma of dhatus and vata dosha. Human body is the unique creation of The Almighty. It has the uniqueproperty in its living state to retain the substances inside the body until it hasuse and then immediately expulse that substance when it is of no use. Thisfunction is happening throughout the body from a cell level up to the level ofall system. In the same pattern, vata performs its dharana karma in the body bythe two ways as follow. 1. Dharana of the shresta dhatus (sara) needful for the living body. 2. Vikshepana of malas (unnecessary substances)
By vikshepana, it keeps the body or organ clean and indirectly helps forthe dharana karma. Always the vikshepana is not mean to drive out of thebody, but vikshepana may be the removal of matter from that particular placewhere it was hold. To detached, from the dravya (dharana of annarasa in thegrahani and the dharana of the agni by the samana vata and after pachanakriya, sarakitta vibhajana with vikshepana in their concerned srotases). Thisdharana and vikshepana karmas of all subdivision of the vata is generatedfrom the pakwashaya. This also supports the importance of apana vata.Now in short the dharana karma of the five subdivisions of the vata.Table 2. 1. Dharana karma of five divisions of vata Subdivisions Dharana Karma Vikshepana (Vibhaga) of vata of Vishaya Of Sthana Of Vishaya Prana Murdha gharana Indriya vishaya dharana Viyoga from the indriya vishaya Udana Urao dharana Vak pravrutyadi Viyoga from the vak dharana pravrityadi karma Samana Grahani dharana Agni, Annarasa dharana Sarakitta vibhajana Vyana Hrdya dharana Rasa raktha dharana Rasa raktha vikshepana Apana Pakwashayadi Mala mootradi dharana Mala mootradi dharana Vikshepana It is clear that prana vata performs the dharana karma of its sthana i.e.murdha and dharana of indriya vishaya. This prana vata also performs thefunction of viyoga in between indriya and indriya vishaya with the Co-ordination of manas. Apana vata also performs the dharana karma of itspakwashaya and dharana of mala mootra, garbha, sukradi vishaya for timebeing and at the time of vikshepana of mala mootradi, apana vata is
responsible for viyoga of its sthana with its vishaya. In this way, apana vata,being in pakwashaya, generate other subdivisions of vata, means give strengthto other sub-division of vata for their dharana and vikshepana karma as itprocesses maximum dharana capacity because of its sthira guna and maximumvikshepana karma. Niskramana karma of apana vata is not just limited to theexpulsion kriya, but the proper withholding and ejection in the proper directionof sukladi is expected with the proper functioning of the apana vata. Apana vata keeps functioning throughout the life, but it shows variationin its retention and expulsion with its subjects.Apana Vata functions – Modern correlation15Colon Movements and Defecation The principal functions of the colon are (1) absorption of water andelectrolytes from the chyme to form solid faeces and (2) storage of fecal matteruntil it can be expelled. The proximal half of the colon, shown in is concernedprincipally with absorption, and the distal half with storage. Because intensecolon wall movements are not required for these functions, the movements ofthe colon are normally very sluggish. Yet in a sluggish manner, the movementsstill have characteristics similar to those of the small intestine and can bedivided once again into mixing movements and propulsive movements.
Large Bowel Motility The motor functions of the colon are to increase the exposure ofintestinal content to the absorption surface by mixing or segment inmovements, to provide storage for intestinal content and to periodically propelthe contents towards the rectum. The contents of the cecum are normally semi-liquid. The stool takes on its normal consistency only in the descending andsigmoid colon. There are dual innervations of both the parasympathetic supply - vagiand pelvic nerves - and the sympathetic - splanchnics and lumbar colonicnerves. The physiological significance of the vagus supply is uncertain. Thepelvic nerves contain both cholinergic excitatory and inhibitory neurons. Thesplanchnic nerves are inhibitory to the proximal colon while the lumbar colonicnerves are inhibitory to the distal colon. There are also inhibitory inputs fromboth the spinal cord and the inferior mesenteric ganglion. The intrinsic innervations of the human colon contains at least two typesof excitatory nerves - cholinergic and non-cholinergic - and also two types ofinhibitory neurons - adrenergic and non-adrenergic.Mixing Movements—“Haustrations.” In the same manner that segmentation movements occur in the smallintestine, large circular constrictions occur in the large intestine. At each ofthese constrictions, about 2.5 centimeters of the circular muscle contracts,sometimes constrict the lumen of the colon almost to occlusion. At the same
time, the longitudinal muscle of the colon, which is aggregated into threelongitudinal strips called the teniae coli, contracts. These combinedcontractions of the circular and longitudinal strips of muscle cause theunstimulated portion of the large intestine to bulge outward into baglike sacscalled haustrations. Each haustration usually reaches peak intensity in about 30seconds and then disappears during the next 60 seconds. They also at timesmove slowly toward the anus during contraction, especially in the cecum andascending colon, and thereby provide a minor amount of forward propulsion ofthe colonic contents. After another few minutes,new haustral contractions occur inother areas nearby. Therefore, thefecal material in the largeintestine is slowly dug into androlled over in much the samemanner that one spades the earth.In this way, all the fecal materialis gradually exposed to the mucosal surface of the large intestine, and fluid anddissolved substances are progressively absorbed until only 80 to 200 millilitersof feces are expelled each day.
Propulsive Movements—“Mass Movements.” Much of the propulsion in the cecum and ascending colon results fromthe slow but persistent haustral contractions, requiring as many as 8 to 15 hoursto move the chime from the ileo-cecal valve through the colon, while thechyme itself becomes fecal in quality, a semisolid slush instead of semi fluid. From the cecum to the sigmoid, mass movements can, for many minutesat a time, take over the propulsive role. These movements usually occur onlyone to three times each day, in many people especially for about 15 minutesduring the first hour after eating breakfast. A mass movement is a modifiedtype of peristalsis characterized by the following sequence of events: First, aconstrictive ring occurs in response to a distended or irritated point in thecolon, usually in the transverse colon. Then, rapidly, the 20 or morecentimeters of colon distal to the constrictive ring lose their haustrations andinstead contract as a unit, propelling the fecal material in this segment furtherdown the colon. The contraction develops progressively more force for about 30 seconds,and relaxation occurs during the next 2 to 3 minutes. Then, another massmovement occurs, this time perhaps farther along the colon. A series of massmovements usually persists for 10 to 30 minutes. Then they cease but returnperhaps a half day later. When they have forced a mass of feces into therectum, the desire for defecation is felt.
Initiation of Mass Movements by Gastrocolic and Duodenocolic Reflexes. Appearance of mass movements after a meal is facilitated by gastrocolicand duodenocolic reflexes. These reflexes result from distention of the stomachand duodenum. They occur either not at all or hardly at all when the extrinsicautonomic nerves to the colon have been removed; therefore, the reflexesalmost certainly are transmitted by way of the autonomic nervous system. Irritation in the colon can also initiate intense mass movements. Forinstance, a person who has an ulcerated condition of the colon mucosa(ulcerative colitis) frequently has mass movements that persist almost all thetime.Act of Defecation The act of defecation is usually subject to conscious nervous control.Defecation is a complex process involving smooth and striated muscle reflexesand cortical control. A desire to defecate occurs, when as a result of a mass movement, somefaeces enter the rectum. An increase in rectal intraluminal pressure of 20 to 25cu.m of water will usually elicit a desire to defecate. This desire may beinduced by straining efforts. The stimulus is thought to come frommechanoreceptors in the rectum responding to distention. These receptors canalso, with a high degree of accuracy differentiate whether the increase inpressure is due to faeces, liquids or flatus. When a mass movement forces feces into the rectum, the desire fordefecation occurs immediately, including reflex contraction of the rectum and
relaxation of the anal sphincters. Continual dribble of fecal matter through theanus is prevented by tonic constriction of (1) an internal anal sphincter, aseveral-centimeters-long thickening of the circular smooth muscle that liesimmediately inside the anus, and (2) an external anal sphincter, composed ofstriated voluntary muscle that both surrounds the internal sphincter and extendsdistal to it. The external sphincter is controlled by nerve fibers in the pudendalnerve, which is part of the somatic nervous system and therefore is undervoluntary, conscious or at least subconscious control; subconsciously, theexternal sphincter is usually kept continuously constricted unless conscioussignals inhibit the constriction. The first response to an urge to defecate at a socially convenient time isto assume the squatting position. One effect of this is to straighten out thenormal angle between the rectum and anal canal. Co-ordinated bearing-downefforts take place, involving the muscles of the abdominal wall, the diaphragmand the pelvic floor. X-ray studies indicate that the pelvic floor descends, andthe lower rectum assumes a funnel shape, while the canal opens up in responseto pressure from above and because the walls are pulled apart by the passivelateral pull of anchoring fascia and the active pull of the cranial fibers oflevator ani as the perineum descends. The internal anal sphincter relaxes and myoelectrical activity in thewhole of the striated sphincter muscle ceases as they also relaxes both reflexlyand by removal of cortical control indicating social approval. Relaxation of thepubo-rectalis sling is accompanied by relaxation and descent of the post-anal
plate to open up the anorectal angle. The degree of straining with defecationvaries according to the amount and consistency of stool. The internal smooth muscle sphincter is supplied by autonomic nervesand the sphincter cloacae by somatic nerves. The autonomic supply of theinternal anal sphincter is the same as that of the lower rectum. Until thefundamental question of whether cholinergic nerves are excitatory andadrenergic nerves are inhibitory or vice versa is resolved, the understanding ofthe nervous control of the internal sphincter remains limited. The puborectalis and external sphincter muscles are supplied by thepudendal nerve which arises from the anterior division of the second, third andfourth sacral nerves and by the perennial branch of the fourth sacral nerve.Cortical control of defecation appears to be centered in the medulla close to thevomiting centre. Most of the time, the rectum is empty of feces. This results partly fromthe fact that a weak functional sphincter exists about 20 centimeters from theanus at the juncture between the sigmoid colon and the rectum. There is also asharp angulations here that contributes additional resistance to filling of therectum.
Defecation Reflexes. Ordinarily, defecation is initiated by defecation reflexes. One of thesereflexes is an intrinsic reflex mediated by the local enteric nervous system inthe rectal wall. This can be described as follows: When feces enter the rectum,distention of the rectal wall initiates afferent signals that spread through themyenteric plexus to initiate peristaltic waves in the descending colon, sigmoid,and rectum, forcing feces toward the anus. As the peristalticwave approaches the anus,the internal anal sphincter isrelaxed by inhibitory signalsfrom the myenteric plexus; ifthe external anal sphincter isalso consciously, voluntarilyrelaxed at the same time,defecation occurs. The intrinsic myenteric defecation reflex functioning byitself normally is relatively weak. To be effective in causing defecation, itusually must be fortified by another type of defecation reflex, aparasympathetic defecation reflex that involves the sacral segments of thespinal cord. When the nerve endings in the rectum are stimulated, signals aretransmitted first into the spinal cord and then reflexly back to the descendingcolon, sigmoid, rectum, and anus by way of parasympathetic nerve fibers in thepelvic nerves. These parasympathetic signals greatly intensify the peristaltic
waves as well as relax the internal anal sphincter, thus converting the intrinsicmyenteric defecation reflex from a weak effort into a powerful process ofdefecation that is sometimes effective in emptying the large bowel all the wayfrom the splenic flexure of the colon to the anus. Defecation signals enteringthe spinal cord initiate other effects, such as taking a deep breath, closure of theglottis, and contraction of the abdominal wall muscles to force the fecalcontents of the colon downward and at the same time cause the pelvic floor torelax downward and pull outward on the anal ring to evaginate the feces. Whenit becomes convenient for the person to defecate, the defecation reflexes canpurposely be activated by taking a deep breath to move the diaphragmdownward and then contracting the abdominal muscles to increase the pressurein the abdomen, thus forcing fecal contents into the rectum to cause newreflexes. Reflexes initiated in this way are almost never as effective as those thatarise naturally, for which reason people who too often inhibit their naturalreflexes are likely to become severely constipated. In newborn babies and insome people with transected spinal cords, the defecation reflexes causeautomatic emptying of the lower bowel at inconvenient times during the daybecause of lack of conscious control exercised through voluntary contraction orrelaxation of the external anal sphincter. This greatly support the Ayurvedicconcept of vegadharana.
Other Autonomic Reflexes That Affect Bowel Activity Aside from the duodenocolic, gastrocolic, gastroileal, enterogastric, anddefecation reflexes that have been discussed earlier, several other importantnervous reflexes also can affect the overall degree of bowel activity. They arethe peritoneointestinal reflex, renointestinal reflex, and vesicointestinal reflex. The peritoneointestinal reflex results from irritation of the peritoneum; itstrongly inhibits the excitatory enteric nerves and thereby can cause intestinalparalysis, especially in patients with peritonitis. The renointestinal andvesicointestinal reflexes inhibit intestinal activity as a result of kidney orbladder irritation. This may be the possible explanation of the interrelation ofdifferent vegas controlled by apana vata. The process of defecation are described here are the collective action ofnervous and muscular system. So it can be concluded that apana vata functionin the GIT is somewhat related with neuromuscular function described bymodern physiology.Micturition Micturition is the process by which the urinary bladder empties itselfwhen it is filled. It is under voluntary control except in infancy. Bladder, neckand external sphincter function as a unit in this act. Parasympathetic excitationcauses contraction of the detrusor muscle and perhaps some dilatation of theinternal sphincter. The parasympathetic fibers arise in the interm-ediolateral
column in the second third and fourth segments of the sacral cord and travel asmedullated fibers in the pelvic nerves to the pelvic plexus. Synapses occurwith postganglionic neurons either here or with fanglion cells within thebladder wall, with gray rami taking a short, direct course to the viseral muscle. Sensory nerve fibers leave the bladder mainly in association with theparasympathetic nerves and enter the spinal cord through the pelvic nerves andsacral plexus. The external sphincter of the bladder, which is a voluntaryskeletal muscle, is controlled by the pudental nerve, which has its origin in thefirst two sacral segments of the spinal cord.The act of Micturition This involves two main steps: First, the bladder fills progressively untilthe tension in its walls rises above a threshold level; this elicits the second step,which is a nervous reflex called the micturition reflex that empties the bladderor, if this fails, at least causes a conscious desire to urinate. Although themicturition reflex is an autonomic spinal cord reflex, it can also be inhibited orfacilitated by centers in the cerebral cortex or brain stem. When the bladder is filled, a nervous reflex called the micturition reflexoccurs that either causes micturition or, if it fails in this, at least causes aconscious desire to urinate. As the bladder approaches the full state, manysuperimposed micturition contractions begin to appear. These are the result of astretch reflex initiated by stretch receptors in the bladder wall and proximalurethra.
Sensory signals are conducted to the sacral segments of the cord throughthe pelvic nerves and then back again to the bladder through theparasympathetic fibers in these same nerves. Once a micturition reflex begins,it is self-regenerative. The micturition reflex is a completely automatic cord reflex, but it canbe inhibited or facilitated by centers in the brain. This reflex is the basic causeof micturition, but the higher centers normally exert final control of micturitionby the following means. 1. The higher centers keep the micturition reflex partially inhibited all the time except when it is desired to micturate. 2. The higher centers prevent micturition even if a micturition reflex occurs, by continual tonic contraction of the external sphincter until a convenient time presents itself. 3. When the time to urinate arrives, the cortical centers can, facilitate the sacral micturition centers to initiate a micturition reflex and inhibit the external sphincter so that urination can occur.Physiologic Anatomy and Nervous Connections of the Bladder The urinary bladder is a smooth muscle chamber composed of two mainparts: (1) the body, which is the major part of the bladder in which urinecollects and (2) the neck, which is a funnel-shaped extension of the body,passing inferiorly and anteriorly into the urogenital triangle and connecting
with the urethra. The lower part of the bladder neck is also called the posteriorurethra because of its relation to the urethra. The smooth muscle of the bladder is called the detrusor muscle. Itsmuscle fibers extend in all directions and, when contracted, can increase thepressure in the bladder to 40 to 60 mm Hg. Thus, contraction of the detrusormuscle is a major step in emptying the bladder. Smooth muscle cells of thedetrusor muscle fuse with one another so that low-resistance electricalpathways exist from one muscle cell to the other. Therefore, an action potentialcan spread throughout the detrusor muscle, from one muscle cell to the next, tocause contraction of the entire bladder at once. On the posterior wall of the bladder, lying immediately above thebladder neck, is a small triangular area called the trigone. At the lowermostapex of the trigone, the bladder neck opens into the posterior urethra, and thetwo ureters enter the bladder at the uppermost angles of the trigone. The trigonecan be identified by the fact that its mucosa, the inner lining of the bladder, issmooth, in contrast to the remaining bladder mucosa, which is folded to formrugae. Each ureter, as it enters the bladder, courses obliquely through thedetrusor muscle and then passes another 1 to 2 centimeters beneath the bladdermucosa before emptying into the bladder. The bladder neck (posterior urethra) is 2 to 3 centimeters long, and itswall is composed of detrusor muscle interlaced with a large amount of elastictissue. The muscle in this area is called the internal sphincter. Its natural tone
normally keeps the bladder neck and posterior urethra empty of urine and,therefore, prevents emptying of the bladder until the pressure in the main partof the bladder rises above a critical threshold. Beyond the posterior urethra, the urethra passes through the urogenitaldiaphragm, which contains a layer of muscle called the external sphincter ofthe bladder. This muscle is a voluntary skeletal muscle, in contrast to themuscle of the bladder body and bladder neck, which is entirely smooth muscle.The external sphincter muscle is under voluntary control of the nervous systemand can be used to consciously prevent urination even when involuntarycontrols are attempting to empty the bladder.Innervation of the Bladder The principalnerve supply of thebladder is by way of thepelvic nerves, whichconnect with the spinalcord through the sacralplexus, mainlyconnecting with cord segments S-2 and S-3. Coursing through the pelvic nervesare both sensory nerve fibers and motor nerve fibers. The sensory fibers detectthe degree of stretch in the bladder wall. Stretch signals from the posterior
urethra are especially strong and are mainly responsible for initiating thereflexes that cause bladder emptying. The motor nerves transmitted in the pelvic nerves are parasympatheticfibers. These terminate on ganglion cells located in the wall of the bladder.Short postganglionic nerves then innervate the detrusor muscle. In addition to the pelvic nerves, two other types of innervation areimportant in bladder function. Most important are the skeletal motor fiberstransmitted through the pudendal nerve to the external bladder sphincter. Theseare somatic nerve fibers that innervate and control the voluntary skeletalmuscle of the sphincter. Also, the bladder receives sympathetic innervationfrom the sympathetic chain through the hypogastric nerves, connecting mainlywith the L-2 segment of the spinal cord. These sympathetic fibers stimulate mainly the blood vessels and havelittle to do with bladder contraction. Some sensory nerve fibers also pass byway of the sympathetic nerves and may be important in the sensation offullness and, in some instances, pain.Transport of Urine from the Kidney Through the Ureters Urine that is expelled from the bladder has essentially the samecomposition as fluid flowing out of the collecting ducts; there are no significantchanges in the composition of urine as it flows through the renal calyces andureters to the bladder. Urine flowing from the collecting ducts into the renalcalyces stretches the calyces and increases their inherent pacemaker activity,
which in turn initiates peristaltic contractions that spread to the renal pelvis andthen downward along the length of the ureter, thereby forcing urine from therenal pelvis toward the bladder. The walls of the ureters contain smooth muscle and are innervated byboth sympathetic and parasympathetic nerves as well as by an intramuralplexus of neurons and nerve fibers that extends along the entire length of theureters. As with other visceral smooth muscle, peristaltic contractions in theureter are enhanced by parasympathetic stimulation and inhibited bysympathetic stimulation. The ureters enter the bladder through the detrusormuscle in the trigone region of the bladder. Normally, the ureters courseobliquely for several centimeters through the bladder wall. The normal tone ofthe detrusor muscle in the bladder wall tends to compress the ureter, therebypreventing backflow of urine from the bladder when pressure builds up in thebladder during micturition or bladder compression. Each peristaltic wave along the ureter increases the pressure within theureter so that the region passing through the bladder wall opens and allowsurine to flow into the bladder. In some people, the distance that the ureter courses through the bladderwall is less than normal, so that contraction of the bladder during micturitiondoes not always lead to complete occlusion of the ureter. As a result, some ofthe urine in the bladder is propelled backward into the ureter, a condition calledvesicoureteral reflux. Such reflux can lead to enlargement of the ureters and, if
severe, can increase the pressure in the renal calyces and structures of the renalmedulla, causing damage to these regions.Micturition Reflex As the bladder fills, many superimposed micturition contractions beginto appear. They are the result of a stretch reflex initiated by sensory stretchreceptors in the bladder wall, especially by the receptors in the posteriorurethra when this area begins to fill with urine at the higher bladder pressures. Sensory signals from the bladder stretch receptors are conducted to thesacral segments of the cord through the pelvic nerves and then reflexively backagain to the bladder through the parasympathetic nerve fibers by way of thesesame nerves. When the bladder is only partially filled, these micturition contractionsusually relax spontaneously after a fraction of a minute, the detrusor musclesstop contracting, and pressure falls back to the baseline. As the bladdercontinues to fill, the micturition reflexes become more frequent and causegreater contractions of the detrusor muscle. Once a micturition reflex begins, it is “self-regenerative.” That is, initialcontraction of the bladder activates the stretch receptors to cause a greaterincrease in sensory impulses to the bladder and posterior urethra, which causesa further increase in reflex contraction of the bladder; thus, the cycle is repeated
again and again until the bladder has reached a strong degree of contraction.Then, after a few seconds to more than a minute, the self-regenerative reflexbegins to fatigue and the regenerative cycle of the micturition reflex ceases,permitting the bladder to relax. Thus, the micturition reflex is a single complete cycle of (1) progressiveand rapid increase of pressure, (2) a period of sustained pressure, and (3) returnof the pressure to the basal tone of the bladder. Once a micturition reflex hasoccurred but has not succeeded in emptying the bladder, the nervous elementsof this reflex usually remain in an inhibited state for a few minutes to 1 hour ormore before another micturition reflex occurs. As the bladder becomes moreand more filled, micturition reflexes occur more and more often and more andmore powerfully. Once the micturition reflex becomes powerful enough, it causes anotherreflex, which passes through the pudendal nerves to the external sphincter toinhibit it. If this inhibition is more potent in the brain than the voluntaryconstrictor signals to the external sphincter, urination will occur. If not,urination will not occur until the bladder fills still further and the micturitionreflex becomes more powerful.Facilitation or Inhibition of Micturition by the Brain The micturition reflex is a completely autonomic spinal cord reflex, butit can be inhibited or facilitated by centers in the brain. These centers include(1) strong facilitative and inhibitory centers in the brain stem, located mainly in
the pons, and (2) several centers located in the cerebral cortex that are mainlyinhibitory but can become excitatory. The micturition reflex is the basic causeof micturition, but the higher centers normally exert final control of micturitionas follows:1. The higher centers keep the micturition reflex partially inhibited, exceptwhen micturition is desired. 2. The higher centers can prevent micturition, evenif the micturition reflex occurs, by continual tonic contraction of the externalbladder sphincter until a convenient time presents itself. 3. When it is time tourinate, the cortical centers can facilitate the sacral micturition centers to helpinitiate a micturition reflex and at the same time inhibit the external urinarysphincter so that urination can occur. Voluntary urination is usually initiated inthe following way: First, a person voluntarily contracts his or her abdominalmuscles, which increases the pressure in the bladder and allows extra urine toenter the bladder neck and posterior urethra under pressure, thus stretchingtheir walls. This stimulates the stretch receptors, which excites the micturitionreflex and simultaneously inhibits the external urethral sphincter. Ordinarily,all the urine will be emptied, with rarely more than 5 to 10 milliliters left in thebladder. By close looking the physiology of urination, it is clear that thecombined action of neural function and higher cortical functions along withmuscular action is the main reason for normal urination. It again points out thatapana vata functions in the urinary system are neuromuscular in nature. In thebroader sense, filtration of urine from the renal tubules, resorption of formed
urine from tubules, flow of urine through the ureter etc. are to be consideredunder the spectrum of apana vata functions.Ejaculation of Semen Sexual reflexes are initiated both by psychic stimuli from the brain andstimuli from the sexual organs. Impulses from these sources coverage on thesacral cord and first result in erection, mainly a parasympathetic function andthen in ejaculation, a sympathetic function. Ejaculation of semen is a frequent accompaniment of erection althoughthe emission of semen can occur through a flaccid penis. Erection is caused byparasympathetic impulses that pass from the sacral portion of the spinal cordthrough the nervi egigentes to the penis. These impulses dilate the arteries ofthe penis and probably simultaneously constrict the veins, thus allowing arterialblood to flow under high pressure into the erectile tissues of the penis. When the sexual stimulus becomes extremely intense, the reflex centersof the spinal cord begin at L-1 and L-2 and pass to the genital organs throughthe hypogastric plexus to initiate emission, which is the fore runner ofejaculation. Emission is believed to begin with contraction of the epididymus,the vas deferens, and the ampulla to cause expulsion of sperm into the internalurethra. Then contractions in the seminal vesicles and the muscular coat of theprostate gland expel seminal fluid and prostatic fluid, forcing the spermforward. All these fluids mix with the mucus already secreted by thebulbourethral glands to form the semen. The process to this point is emission.
The filling of the internal urethra then elicits signals that are transmittedthrough the pudendal nerves to the sacral regions of the cord. In turn, rhythmicnerve impulses are sent from the cord to skeletal muscles that encase the baneof the erctile tissue causing rhythmic, wave like increase in pressure in thistissue, which ejaculates the semen from the urethra to the exterior. This is theprocess of ejaculation.Male Sexual Act - Neuronal Stimulus for the Male Sexual Act The most important source of sensory nerve signals for initiating themale sexual act is the glans penis. The glans contains an especially sensitive sensory end organ system thattransmits into the central nervous system that special modality of sensationcalled sexual sensation. The slippery massaging action of intercourse on theglans stimulates the sensory end-organs, and the sexual signals in turn passthrough the pudendal nerve, then through the sacral plexus into the sacralportion of the spinal cord, and finally up the cord to undefined areas of thebrain. Impulses may also enter the spinal cord from areas adjacent to the penisto aid in stimulating the sexual act. For instance, stimulation of the analepithelium, the scrotum, and perineal structures in general can send signals intothe cord that add to the sexual sensation. Sexual sensations can even originatein internal structures, such as in areas of the urethra, bladder, prostate, seminal
vesicles, testes, and vas deferens. Indeed, one of the causes of “sexual drive” isfilling of the sexual organs with secretions. Mild infection and inflammation of these sexual organs sometimes causealmost continual sexual desire, and some “aphrodisiac” drugs, such ascantharidin, increase sexual desire by irritating the bladder and urethralmucosa, inducing inflammation and vascular congestion.Psychic Element of Male Sexual Stimulation. Appropriate psychic stimuli can greatly enhance the ability of a personto perform the sexual act. Simply thinking sexual thoughts or even dreamingthat the act of intercourse is being performed can initiate the male act,culminating in ejaculation. Indeed, nocturnal emissions during dreams occur inmany males during some stages of sexual life, especially during the teens.Integration of the Male Sexual Act in the Spinal Cord. Although psychic factors usually play an important part in the malesexual act and can initiate or inhibit it, brain function is probably not necessaryfor its performance because appropriate genital stimulation can causeejaculation in some animals and occasionally in humans after their spinal cordshave been cut above the lumbar region. The male sexual act results frominherent reflex mechanisms integrated in the sacral and lumbar spinal cord, andthese mechanisms can be initiated by either psychic stimulation from the brainor actual sexual stimulation from the sex organs, but usually it is a combination
Penile Erection—Role of the Parasympathetic Nerves. Penile erection is the first effect of male sexual stimulation, and the degree of erection is proportional to the degree of stimulation, whether psychic or physical. Erection is caused by parasympathetic impulses that pass from the sacral portion of the spinal cord through the pelvic nerves to the penis. These parasympathetic nerve fibers, in contrast to most other parasympathetic fibers, are believed to release nitric oxide and/or vasoactive intestinal peptide in addition to acetylcholine. The nitric oxide especially relaxes the arteries of the penis, as well as relaxes the trabecular meshwork of smooth muscle fibers in the erectile tissue of the corpora cavernosa and corpus spongiosum in the shaft of the penis. This erectile tissue consists of large cavernous sinusoids, which are normally relatively empty of blood but become dilated tremendously when arterial blood flows rapidly into them under pressure while the venous outflow is partially occluded. Also, the erectile bodies, especially the two corpora cavernosa, are surrounded by strong fibrous coats; therefore, high pressure within the sinusoids causes ballooning of the erectile tissue to such an extent that the penis becomes hard and elongated. This is the phenomenon of erection.