Respiratory System Anatomy and Physiology Notes

HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 1
CHAPTER NO:11
RESPIRATORY SYSTEM
Prepared by,
RAMDAS BHAT
Associate Professor
Karavali college of Pharmacy
Mangalore
7795772463
Ramdas21@gmail.com

RAMDAS BHAT
INTRODUCTION
• Body requires oxygen for various process
• Carb. Dioxide is formed as the end product of metabolism
• These CO2 should be removed from body
• Fresh O2 are again taken back
• The process by which the body takes O2 and releases the CO2 are called as Respiration
• Inspiration involves the taking up of O2 by body.
• Expiration involves the release of CO2 by body
DIVISIONS
1. External respiration:
• Also called as the breathing or ventilation
• It involves the absorption of O2 and removal of CO2 from body as a whole.
• Transport of gases in blood.
2. Internal respiration:
• Also called as the cellular respiration
• Utilization of O2 and release of CO2 by the cells and exchange of gases between cells and
tissue medium.
Normal Respiratory Rate at Different Age
a) Newborn: 30 to 60 times/minute
b) Early childhood: 20 to 40 times/minute
c) Late childhood: 15 to 25 times/minute
d) Adult: 12 to 16 times/minute.
RESPIRATORY SYSTEM

RAMDAS BHAT
FUNCTIONAL ANATOMY OF RESPIRATORY TRACT:
Respiratory tract is the anatomical structure through which air moves in and out. It includes
nose, pharynx, larynx, trachea, bronchi and 2 lungs.
NOSE & NASAL CAVITY:
• Tip of nose is present in the anterior portion
• Base is present in between eye sockets.
• Highly vascularised and contain the ciliated Columnar epithelium that secretes Mucous.
• Nose also contains the nostrils these helps in transport of gases in and out of body.

RAMDAS BHAT
NOSE & NASAL CAVITY:
• Nasal cavity is deep hollow cavity
• Stretches from over hard palate at back to between eye sockets
• Divided into 2 halves by Nasal septum
• Each nasal cavity has FLOOR, ROOF, LATERAL & MEDIAL wall.
• Floor formed by roof of the mouth ie palatine bone
• Roof formed by the sphenoid, ethmoid, frontal and nasal bone.
• Medial wall formed by Nasal septum
• Nasal septum has anteriorly hyaline cartilage
• Posteriorly by plate of ethmoid and vomer bone
• Lateral wall formed by the Maxilla, ethmoid, inferior concha.
• Posterior wall formed by Posterior wall of pharynx
• Paranasal sinuses are small cavities having air and open up into nasal cavity.
OLFACTORY MUCOUS MEMBRANE:
• Lined with the pseudostratified ciliated epithelium
• Contains olfactory receptor hairs and cell body of the bipolar neurons.
• These carry the impulses to the brain and helps in the process of the olfaction.
PHARYNX:
• Common passage for food & air
• Muscular tubule made of mucosal membrane, 12cm length
• From base of the skull extends till 6th cervical vertebrae and it has 3 regions
a) Nasopharynx
b) Oropharynx
c) Laryngopharynx
Functions are passage for food and air, help in hearing, palatine and pharyngeal tonsils help
in defence mechanisms.

RAMDAS BHAT
LARYNX:
• Lies in-front of neck
• Extends from tongue hyoid bone to the trachea
• Longer after puberty
• Lies infront of the C3,4,5,6 vertebrae
• They are made of cartilage
• Attached together with joints, ligaments and membranes.
The 4 main cartilage of the larynx are:
a) Thyroid cartilage
b) Cricoid cartilage
c) Epiglottic cartilage
d) Arytenoid cartilage
Functions:
• Passage of air into trachea
• Vocal cords produce sounds
• During swallowing larynx moves upwards in order to prevent passage of food into
respiratory passages

RAMDAS BHAT
TRACHEA:
• Cartilaginous and membranous tube
• 10-11cm (L)
• Lies infront of oesophagus
• Continuation of larynx
• Starts from the front of 6th C vertb.
• End bifurcating into 2 branches or bronchi, ie.
left and right.
• Bifurcating occurs at T5 vertb level.
• Made of 16-18 C shaped cart. Rings
• Incomplete posteriorly
• Gap filled with Fibro elastic membrane and
Trachealis muscle
BRONCHI:
• They are the Bifurcation of trachea.
• Starts at level of T5 vertb
• Right bronchus is shorter(2.5cm) and thicker
• Each bronchus will enter lung at hilum
• Bronchi will branch into 3 sub branches for each lobe
• Each lobular bronchus will divide in 10 tertiary bronchi.
• Left bronchus is longer(5cm) narrow and oblique
• Divides into 2 lobular branches
• Each lobular branches will subdivide into 8 tertiary branches.
• Tertiary bronchi later branches to form small divisions called as the terminal bronchioles.
Functions:
• Passage of air into alveoli of lungs
• Mucous produced from ciliated epithelium. These traps microorganism and dust particles.

RAMDAS BHAT
ALVEOLI:
• Bronchioles finally arise the alveolar duct
• That lead via atria to form tiny sac like structure called Alveoli.
• Also called as the pulmonary alveoli
• 2 lungs contain total of 300million alveoli and has surface area of 70sqmm
• Alveoli has squamous type of epithelium has 2 types of cells
• Type 1 are flat cells and type 2 are thicker and has a granules secreting Surfactant.
• Other than all these cells it contains PAM (Pulmonary Alveolar Macrophage) Lymphocytes
and Plasma cells secreting immunoglobulin.
LUNGS:
• Pair of respiratory organ.
• Lying in the thoracic cage
• Conical in shape
• Spongy in texture and brown coloured
• Has a) Apex b) Base c) Coastal and Medial surfaces
• Apex is blunt
• Base is semilunar and concave
• Coastal surface large and convex
• Medial surface is concave
• Anteriorly Mediastinum posteriorly vertebrae.

RAMDAS BHAT
LOBES OF LUNGS:
• Right lung has 3 lobes ie superior, middle and inferior separated by the 2 fissures oblique and
horizontal
• Left lung has 2 lobules ie Superior and Inferior and has Oblique fissure
• Each lobe are divided into large no. of lobules
PLEURA:
• Serous membrane with flattened epithelium
• Outer Parietal and inner Visceral pleura.
• Parietal pleura adherent to inner surface of chest wall and thoracic surface of diaphragm
• Visceral pleura adherent to lungs
• Space between pleura is called Pleural cavity filled with columnar epithelium.

RAMDAS BHAT
FUNCTIONS OF LUNGS:
Respiratory function
• Uptake of O2 from atm. This O2 are taken to the body tissues through the blood where they
are utilized
• Expulsion of the CO2 into the atm. CO2 produced in the tissues are taken up by the blood
and are taken to the lungs where they are expelled
NON-Respiratory functions
• Defence mechanism
• Synthesis of surfactant
• Fibrinolysis and removes clot
• Converts AT-1 to AT-2 by ACE
• Temp. regulation
• Acid base balance, excretory and helps in voice production.
RESPIRATORY MEMBRANE
• The air in alveoli is separated from blood in pulmonary capillary by a wall called Respiratory
membrane ie. alveolar wall and capillary wall
• No fluid is present here
• Thickness is 0.5 μm
• Gaseous exchange happens within a fraction of second.

RAMDAS BHAT
LUNG VOLUMES AND LUNG CAPACITIES:
STATIC LUNG VOLUMES:
1. TIDAL VOLUME: Volume of air breathed in and out of lungs at rest. NV= 500ml
2. INSPIRATORY RESERVE VOLUME: Maximum volume of air that can be inspired after the
normal static inspiration. NV= 2000-3200 ml
3. EXPIRATORY RESERVE VOLUME: Maximum volume of the air that can be expired after
normal static expiration. NV= 750-1000ml
4. RESIDUAL VOLUME: Volume of air that remained in the lungs after the maximal expiration.
NV= 1200ml
STATIC LUNG CAPACITY:
1. INSPIRATORY CAPACITY: Maximal volume of air that is inspired after completing resting
expiration. TV+IRV= IC, NV= 2500-3700ml.
2. EXPIRATORY CAPACITY: Maximal volume of air that is expired after completion of the resting
Inspiration. TV+ERV= EC, NV= 1200-1500ml.
3. VITAL CAPACITY: Maximal volume of air expelled from lungs forcefully following maximal
inspiration at rest. NV 4.8L(M), 3.2(F)
4. FUNCTIONAL RESIDUAL CAPACITY: Volume of the air contained in the lungs after completion
of resting expiration. NV= 2.5L
5. TOTAL LUNG CAPACITY: Volume of air contained in the lungs after maximal inspiration. NV=
6L.

RAMDAS BHAT
DYNAMIC LUNG CAPACITY AND VOLUME:
1. TIMED VITAL CAPACITY/ FORCED VITAL CAPACITY: Maximum volume of air that is breathed
out forcefully and rapidly after maximum inspiration. 80-120%
2. MINUTE VENTILATION/ PULMONARY VENTILATION: Volume of the air expired or inspired
by the lungs /min
PV= TV x RR(RESPIRATORY RATE) /MIN
PV= 500x12= 6L/min
3. MAXIMUM BREATHING CAPACITY/ MAXIMUM VOLUNTARY VENTILATION/ MAXIMUM
VENTILATION VOLUME: Maximum volume of the air that can me moved in and out of the
lungs per minute by the maximum voluntary effort. NV= 100L/min.

RAMDAS BHAT
MECHANISM OF RESPIRATION
❑ MECHANISM OF INSPIRATION:
• An active process
• Diaphragm supplied with phrenic nerves gets flattened up
• Enlargement of thorax occurs
• Ribs moves outwards and upwards
• Happening due to contraction of external intercostal muscles(T1,2)
• Anterior posterior and transverse increase in diameter of chest
• Parietal pleura gets pulled by the enlarging thorax
• Due to which the Visceral pleura also gets pulled increasing size of lungs
• Thereby the bronchioles, bronchus gets stretched, Causing more amount of air to move in
lungs. INSPIRATION occurs.
• Others muscles that are involved are STERNOCLEDOMASTOID and SCALENE in neck and
INTRINSIC MUSCLES of larynx.
• These muscles play imp role in the Forceful inspiration.
❑ MECHANISM OF EXPIRATION:
• Passive process
• Diaphragm gets relaxed to form dome shaped structure
• Size of the thorax reduces
• The pleural membrane comes back to normal state along with Visceral membrane
• Lungs gets back to normal state
• Air inside the lungs expels out
• Muscles involved are internal intercostal muscle
• Abductors of vocal cord, Anterior abdominal walls.
TRANSPORT OF GASES:
Transport of gases mainly dependent on the PARTIAL PRESSURE.

RAMDAS BHAT
TRANSPORT OF OXYGEN:
• Transportation of the oxygen from the alveoli into the blood happens in the respiratory
membrane
• The blood will then transport the blood to the tissues
• PP O2 in the alveoli 104mm Hg
• PP O2 in the pulmonary capillary at the arterial end is 40mm Hg
• Due to the pressure gradient the O2 will now diffuse from the alveoli into blood in the
Pulmonary capillary
• PP O2 in the pulmonary capillary in the Venus end is 90mm Hg.

RAMDAS BHAT
• The PP O2 in the arterial end of tissues 95mm Hg
• The PP O2 in the interstitial fluid is 40mm Hg
• Due to the pressure gradient the O2 will now diffuse from Capillary to the interstitial fluid
• PP O2 inside cell is 23mm Hg
• Now the O2 will diffuse from the Interstitial fluid into the cell due to pressure gradient
• The PP O2 in venules in the tissue capillary end is 40mm Hg.
• It gives the relationship between the partial pressure of O2 and the % saturation
• The graphical representation between the partial pressure of O2 and the % saturation is called Oxygen
dissociation curve
• A graph is obtained by plotting Partial pressure of O2 against the % saturation
• S shaped graph is obtained. Sigmoid Graph
• Initially there is sharp increase in the % saturation with increase in pp of O2
• At a point of the pp O2 is 40 mm Hg the % saturation is 70%
• Once the PP O2 reaches 95 mm Hg the % saturation will be 97%
• Further increase in the PP O2 there will not be any further increase in the % saturation and Plateau is
reached.
TRANSPORT OF CARBON DIOXIDE:
• CO2 gets transported from the tissues to the lungs
• PP CO2 at the arterial end of the tissue capillary is 40mm Hg
• PP CO2 in the cell is 46mm Hg
• Due to the pressure gradient the CO2 from tissues diffuses into the blood.
• PP CO2 at the venous end of the tissue capillary is 45mm Hg
• PP CO2 in the alveoli is 40mm Hg
• The partial pressure in the arterial end of the Pulmonary capillary is 45mm Hg
• Now due to pressure gradient the air CO2 will move into alveoli

RAMDAS BHAT
FORMS IN WHICH CO2 IS TRANSPORTED
• 7% of CO2 will be transported in blood in the dissolves state i.e., as a physical solution
• 23% of CO2 binds with the protein of the blood i.e., globin, albumin etc
• The CO2 binds with the haemoglobin to form CARBAMINO HAEMOGLOBIN, which then binds
with the other proteins called as CARBAMINO PROTEINS.
• Rest 70% of CO2 gets transported as a bicarbonate ion
• CO2 from the plasma diffuses into the RBC
• In RBC CO2 reacts with H2O to form CARBONIC ACID catalysed by enzyme Carbonic acid
anhydrase
• Carbonic acid then dissociates to form H+ and HCO3, HCO3 formed then diffuses from RBC to
plasma.
• To compensate the loss of the neg. charged ions in the RBC and to prevent the electrical
disturbance in RBC the neg. charged Chloride ions will move into the RBC
• This is called as CHLORIDE SHIFT.
• Once the deoxygenated blood moves to lungs whole process gets reversed.
• CO2 are regained, that are then expelled from the alveoli to atmosphere
• 100ml of the venous blood contain 52ml CO2, 100ml of the atrial blood contain 48ml of the
CO2
• Hence 100ml blood releases 4ml of CO2 to alveoli
• Blood releases 200ml of the CO2 to alveoli/min.

RAMDAS BHAT
HALDANE EFFECT:
• The CO2 combines with the blood more easily with the deoxy Hb than the OXYHAEMOGLOBIN
• Thus, whenever the conc. of the O2 increases in the blood the more and more CO2 get
released from the blood
• This process is called as the HALDANE EFFECT.
RESPIRATORY QUOTIENT:
• Ratio of CO2 produced to the O2 consumed.
• NV= 0.8
REGULATION OF RESPIRATION:
• They are important for the controlling rate and depth of the respiration as per the
physiological demand
• It helps in maintaining 3 important components:
➢ Maintaining level of O2 and CO2 in blood
➢ It supplies the O2 as per the metabolic demand of the body.
➢ Helps in regulating acid-base balance.
• Regulation happens in 2 methods
❖ Nervous regulation
❖ Chemical regulation
NEURONAL REGULATION:
• Brought about by 2 systems
1. Autonomic regulation of the respiration
2. Voluntary control of respiration
1. Autonomic regulation of the respiration:
• There are the group of the neurons in the brain stem that regulates the respiration
• They are present in the medulla and the pons, they form the respiratory centres
1. MEDULLARY RESPIRATORY CENTRES:
• They helps in the rhythmic discharge
• 2 neurons are found I and E neurons

RAMDAS BHAT
• I neurons discharge during inspiration
• E neurons discharge during expiration
• Both I and E neurons show a reciprocal innervation i.e., they are inhibitory to each other.
2. PONTINE RESPIRATORY CENTRES:
• A group of the neurons in the lower pons that are tonically active and they activate the I
neurons in medulla are Apneustic centre
• A region in the upper pons that contains both I and E neurons are called Pneumotaxic centre.
They inhibit the neurons in the Apneustic centre.

RAMDAS BHAT
Voluntary Control Of Respiration:
• The rate and depth of the respiration can be changed for a specific period of time i.e.,
hyperventilation, forceful inspiration and expiration and in breath holding
• The pathway is through the CORTICOSPINAL TRACT.
• They originate from the Cerebral cortex and end to the spinal motor neurons that innervates
into the respiratory group of muscles.
CHEMICAL REGULATION:
• The chemical regulation mechanism maintains the normal ventilation by maintaining the
normal partial pressure of CO2 ie 40mm Hg.
• It also helps in maintaining the concentration of O2 and H+.
• These are done by the Respiratory Chemo receptors
• Respiratory chemoreceptors are of 2 types:
• Peripheral chemoreceptors
• Medullary chemoreceptors
1. Peripheral chemoreceptors:
• They are present in the Carotid body and the Aortic arch
• They get stimulated due to the hypoxia
• Vascular stasis: Dec. in blood flow
• Asphyxia: Dec. in O2 and excess of CO2
2. Medullary Chemoreceptors:
• Located in medulla near to the respiratory centre
• Get stimulated by H+ conc. in CSF
• The CO2 enters brain and in CSF it mixes with water and gets hydrated.
• Formation of the carbonic acid takes place along with their dissociation to form the H+ and
bicarbonate ions.

RAMDAS BHAT
Some definitions:
1. Dyspnoea: difficulty in breathing or shortness of breathing causing discomfort
2. Apnoea: inhibition or stoppage of the breathing
3. Hypoxia: lack of O2 in tissue.
4. Cyanosis: bluish discoloration of the skin and mucous membrane when Hb level is more than
5g/dl. Observed in the lips, nail, earlobes and cheeks.
5. Asphyxia: Dec. in O2 and increase in CO2 in body.
ARTIFICIAL RESPIRATION:
• The process of the restoration of the respiratory activity which has stopped suddenly.
• Respiratory arrest can cause due to the drowning, poisoning, suffocation, electrocution,
Myocardial infarction or Cerebrovascular accidents.
• This can lead to the death of the brain or other vital organs if not restored within 2-3 mins.
• Thus, various methods have been implemented in order to treat the process of the
respiratory failure
• The 2 methods are used widely 1. MANUAL METHOD 2. ARTIFICIAL METHOD.
MANUAL METHODS:
• These include SCHAFER’S METHOD, SYLVESTER’S METHODS, EVE’S ROCKING METHOD,
HOLGER-NEILSON’S METHOD AND MOUTH TO MOUTH METHOD
ARTIFICIAL METHODS:
• DRINKER’S METHOD AND BRAGG PAUL’S METHOD.

RAMDAS BHAT
SCHAFER’S METHOD:
• Patient is prone to rest and the pillow is placed under his chest and the head is turned to one
side.
• Operator kneels down side to him
• The palms of the operator are placed on the hip region or lower back and with his palms he
puts the pressure over the back
• And this stage the intra-abdominal pressure incr. diaphragm moves up and air is expired out
of lungs.
• Process is repeated 12 times.
HOLGER-NEILSON’S METHOD:
• Patient is made to rest in prone position with face on other side and arms folded underneath
• Operator places his palms over the shoulder on the back of the patient
• Operator now rocks the back part of chest and puts pressure over it and rocking is increased
in order to increase the pressure inside the lungs.
• After waiting a while, the operator now rocks over the arm nearer to elbow sliding his palms
over the arms of patient.
• While sliding the arms the volunteer now raises the arm of patient thus causing force full
inspiration
• Again, the arms are folded for the fresh artificial respiration.

RAMDAS BHAT
SYLVESTER’S METHOD:
• Here the patient is placed in a supine position
• The operator is placed at the head of the patient
• He holds the arms of the patient and folds the arms over the chest of the patient
• He compresses the chest of the patient at the same time.
• That causes the increase and decrease in the size of the thoracic cavity
• Thus, pushing the air in and out of the lungs
• Done at the same rate as that of the Schafer's method.
EVE ROCKING’S METHOD:
• In this method the patient is tied down onto a stretcher
• The patient is now tilted both head and feet at 45 degrees
• The process is carried out for 8-9 times/min
• The 7 sec time is given for tilting head and feet
• 4 sec for head and 3 second for tilting the feet
• When head is down the weight on the abdomen will move the
diaphragm up and air is pushed out of lungs
• When feet is down the diaphragm compresses and the air will
move into lungs.

RAMDAS BHAT
MOUTH TO MOUTH METHOD:
• Simplest and most common method
• Patient is placed in a supine position
• The mouth is opened and the mucous attached to the nostrils
mouth and to the throat is removed.
• The operator should stay sideways and now he should close the
nose of patient with a finger or thumb.
• The operator now breaths deeper and keep his mouth over the
mouth of the patient and the air is blown into the mouth of the
patient.
• This is continued till the chest of the patient is raised.
CARDIO PULMONARY RESUSCITATION(CPR):
• Many cardiac activities are stopped due to the stoppage in the breathing
• This method can be a lifesaving method
• It involves external heart massage along with the artificial respiration.
• This method should be performed within 3-5 mins.

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