Human nutrition


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Human nutrition

  2. 2. The materials which provide the two primary requirements of life, namely,energy andraw materials (matter) are called nutrientsThe processes which are responsible for providing energy arenutrition and respiration.Nutrition is the sum total of all processes through which the food is taken in,digested, absorbed, and utilized and finally, the undigested matter iseliminated outside the body.Thus, nutrition includes the processes like ingestion, digestion, absorption,assimilation and egestion (defecation). dr. aarif
  3. 3. the process in which food is taken inside the body. This Ingestion ingested food is then digested. process during which complex, non-diffusible and non-N absorbable food substances are converted into simple, DigestionU diffusible and absorbable substances by enzymes. .T process in which the simple substances get diffused intoR the blood. Thus, the absorbed food is now carried to AbsorptionI each and every tissue cell of the body where it isT assimilatedI the process by which the protoplasm is synthesized into AssimilationO each cell of the body by utilizing simple food substances.N process of the elimination of the indigestible remains of Egestion the food from the alimentary canal (defecation or evacuation).. dr. aarif
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  5. 5. HUMAN DIGESTIVE SYSTEMAlimentary Canal Accessory Glands Mouth parotid Salivary Palate Sub lingual Glands Buccal Cavity Tongue Sub mandibular Teeth Naso-Pharynx Pancreas Pharynx Oro-Pharynx (Exocrine part) Laryngo-Pharynx Liver Oesophagus Cardiac Stomach Fundus Pylorus Duodenum Small Int Jejunum Ileum Caecum Large Int Colon Anus Rectum dr. aarif
  6. 6. MOUTHUppermost Transverse slit-like opening of alimentary canalBounded by 2 fleshy lipsLeads to a large cavity called ORAL or BUCCAL CAVITY BUCCAL CAVITYLarge space bounded : above by the Palate sides by the Jaws ( they bear the teeth) below by the Throat ( they support the tongue)Lined by : Squamous epithelium and mucous membranePresence of : TONGUE, TEETH & SALIVARY GLANDS dr. aarif
  7. 7. TONGUE--Thick muscular protrusible organ--Att. To the floor of buccal cavity by a : fold of mucous membrane – LINGUAL FRENULUM bony attachments – styloid process and hyoid bone--Upper surface shows presence of numerous raised projections called PAPPILAE which contain sensory receptors for taste (gustatory receptors)--USES : 1. Taste 2. Mixing of food with saliva 3. Deglutition ie swallowing dr. aarif
  8. 8. TEETHPresent on both the upper and the lower jawThe following terminologies describe the teeth : 1. THECODONT : Fixed in the sockets of jaw bones 2. HETERODONT : Different types of teeth a) Incisors - chisel shaped , for biting, cutting and gnawing b) Canines – Pointed, used for ripping and shredding c) Premolars – for grinding d) Molars – for grinding 3. DIPHYODONT : Teeth appear twice during lifetime 2 (I) 1 (C) 0 (PM) 2 (M) a) Decidious : 20 in number 2 1 0 2 2 (I) 1 (C) 2 (PM) 3 (M) b) Permenant : 32 in number 2 1 2 3
  9. 9. DECIDIOUS PERMENANT 2 (I) 1 (C) 2 (PM) 3 (M)2 (I) 1 (C) 0 (PM) 2 (M) 2 1 2 32 1 0 2 dr. aarif
  10. 10. CLINICAL APPLICATION : ROOT CANAL THERAPYRoot canal therapy is a multistep procedure in which all traces of pulp tissue areremoved from the pulp cavity and root canals of a badly diseased tooth.After a hole is made in the tooth, the canal are filed out and irrigated to removethe bacteriaThen the canals are treated with medication and sealed tightly.The damaged crown is repaired
  12. 12. PHARYNXThe buccal cavity leads in to the pharynx. It can be divided into 3 regions1. NASOPHARYNX : lies behind the nasal cavities having the internal nares and Eustachian canals2. OROPHARYNX : lies behind the buccal cavity and forms the passage for the bolus of food3. LARYNGOPHARYNX : lowest part of Pharynx and has 2 openings a) Glottis which leads to the trachea b) Gullet which leads to the oesophagus
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  14. 14. OESOPHAGUSThe oesophagus is 25 cm long, narrow, musculartube connecting the pharynx to the stomachIt is lined by stratified squamous epitheliumcontaining mucous glandsFood moves through the oesophagus due torhythmic contractions of the longitudinal andcircular musclesThis movement is called as PERISTALSIS dr. aarif
  15. 15. CLINICAL APPLICATION :CARDIA ACHLASIAFailure of the sphincter to relax causes impediment for thefood to pass through the oesophagus. Distention ofoesphagus can lead to pain which is often confusedwith heart pain
  16. 16. CLINICAL APPLICATION :HEARTBURNFailure of the sphincter to close after the passage of food inthe stomach can cause the contents of the stomach to revertback in the oesophagus thereby leading to irritation ofoesophageal wall causing a burning sensation called as Heartburn
  17. 17. STOMACHSac like , ‘J’ shaped, 25-30 cms long3 parts : i) Cardiac ii)Fundus iii) PyloricSphincters at both the ends of stomachi) Cardiac Sphincter : prevents regurgitation of food back into the buccal cavityii) Pyloric Sphincter : Regulates the passage of food into the duodenumFUNCTIONS :i) Churns the food ie breaks the food intosmaller pieces which facilitates the mixingof food with gastric juice dr. aarif
  18. 18. SMALL INTESTINELongest part of the Digestive system, it is 6m long and 2.5 cms broad . It is compactly coiled in the abdominal cavityThe coils are held together by connective tissuemembranes called mesenteries supportingthe blood vessels, lymph vessels and nerves3 parts:i) DOUDENUM : U-shaped about 25 cms long Bile duct and pancreatic duct opens in theduodenumii) JEJUNUM : 2.5 m long and narrower thanduodenumiii) ILEUM : Lower part of the smallintestine 3.5 m long and opens in the largeintestine dr. aarif
  19. 19. 1.5 m long, arranged around the mass of small LARGE INTESTINE intestine in the form of a ? marki) CAECUM : small blind sac off the colon,Present at the junction of ileum and colon. Atthe junction is a ileocaecal valve thatregulates passage of substances from thesmall to the large intestine. Caecum bears asmall worm like vestigial organ called asappendix(functional in herbivores for thedigestion of cellulose)ii) COLON : Anterior region divided into 3 parts a) Ascending colon b) Transverse colon c) Descending coloniii) RECTUM : Posterior region, about 15 – 20 cms long. The rectum has longitudinal folds and large blood vessels. Undigested matter called faecal matter istemporarily stored before egestion dr. aarif
  20. 20. ANUS The rectum opens to the outside by the opening called ANUS . It is guarded by asphincter. It removes undigested matter outside by a process known asDEFEACATION dr. aarif
  21. 21. HUMAN DIGESTIVE SYSTEMAlimentary Canal Accessory Glands Mouth parotid Salivary Palate Sub lingual Glands Buccal Cavity Tongue Sub mandibular Teeth Naso-Pharynx Pancreas Pharynx Oro-Pharynx (Exocrine part) Laryngo-Pharynx Liver Oesophagus Cardiac Stomach Fundus Pylorus Duodenum Small Int Jejunum Ileum Caecum Large Int Colon Anus Rectum dr. aarif
  22. 22. SALIVARY GLANDS1. SUBLINGUAL GLAND2. SUBMANDIBULAR GLAND3. PAROTIDThe Salivary glands have 2 types of secretory cells :a) Serous cells : produces a watery fluid containing enzyme SALIVARY AMYLASE or PTYALINb) Mucous cells : produces mucous. It binds the food, makes it slippery so that it can be easily swallowed
  23. 23. LIVER-Largest gland of the body.-Reddish brown in colour-Weighing about 1.5 kgs in adult-Located on the right side, just below the diaphragm-Made up of 2 lobes-Produces bile juice which gets stored in a small bag-like structure called gall-bladderFunctions of the liver:-Liver secretes bile which emulsifies fats and makes the food alkaline.-It stores excess of glucose in the form of glycogen which is used during starvation.-In liver, excess amino acids are converted into ammonia by the process called deamination.-It synthesizes vitamin A, D, K and B12.-Blood proteins like prothrombin and fibrinogen are formed in the liver.-It produces red blood cells during early development thus working as a hematopoietic organ.-Kupffer cells digest old R.B.C.’s dr. aarif
  24. 24. PANCREASIt is a leaf-shaped gland lying in the gapbetween the duodenum and the stomach.It is a mixed gland because some part of itis exocrine in function, i.e. its secretion iscarried by the ducts, while the other part isendocrine, i.e. its secretion is directlypoured into the blood stream. dr. aarif
  25. 25. HISTOLOGY dr. aarif
  26. 26. HISTOLOGY OF STOMACH dr. aarif
  27. 27. SEROSA:Outer protective covering of the stomach.Outer layer of squamous epithelium (mesothelium)Inner layer of connective tissue.MUSCULARIS :Thick layer made up of 3 kinds of muscles 1. Outer longitudinal muscles 2. Middle circular muscles and 3. Inner oblique smooth muscles. This muscular layer is the thickest part responsible for the churning movement in thestomach.SUBMUCOSA:Connective tissue layer containing blood vessels, lymph vessels and nerves.It supports mucosaMUCOSA:It is the innermost layer thrown into large folds called rugae. It is made up of threeparts:Muscularis mucosa: It is prominent and formed of outer longitudinal and innercircular muscles.Lamina Propria: It contains the gastric glands.Epithelium: It is columnar and folded to form gastric glands. dr. aarif
  28. 28. GASTRIC GLANDThese are simple, tubular, branched or un-branched glands, embedded in the lamina propria.Each is made up of the following 3 types of cells MUCOUS CELLS: They are present in the neck region and secrete mucous. PARIETAL CELLS (OXYNTIC CELLS): large oval cells. secrete dilute HCI and an intrinsic factor [necessary for absorption of Vitamin B12.(def .of B12 leads to pernicious anaemia)] CHIEF CELLS (PEPTIC CELLS): They are pyramid shaped Present deep in the base of the glands. Secretes enzyme pepsinogen dr. aarif
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  32. 32. HISTOLOGY OF LIVER dr. aarif
  33. 33. HISTOLOGY OF PANCREAS The exocrine part is made up of pancreatic lobules called acini. They are flask-shaped and formed of a single layer of large glandular pyramid-shaped cells. These cells secrete the pancreatic juice. This juice is alkaline in nature with pH of 8.8. About a litre of pancreatic juice is secreted each day. The endocrine part is made up of groups of cells present in the connective tissue between the acini. These are called Islets of Langerhans. 1. ‘A’ or alpha α cells that secrete glucagon 2. ‘B’ or beta β cells that secrete insulin. Both these hormones together control the blood sugar level. 3. delta cells secrete somatostatin hormone, which decreases glucagon and insulin secretion. dr. aarif
  34. 34. PHYSIOLOGY OF DIGESTION PHYSICAL CHANGES + CHEMICAL CHANGES breaking up of the food Chemical changes are into smaller finer particles brought about by the mastication, action of different churning and enzymes. peristaltic movementsThe food eaten is insoluble and it cannot become a part of our body. Thefood undergoes many physical and chemical changes so that it is convertedinto the simple soluble absorbable form. This is absorbed into the mucosacells of the alimentary canal and then diffused into the blood capillaries
  35. 35. DIGESTION IN BUCCAL CAVITYMASTICATION will break down the food in to smaller particles TONGUE mixes the food with SALIVA secreted from the SALIVARY GLANDS PTYALIN SALIVA LYSOZYME STARCH MALTOSE Anti-bacterial (Poly) pH 6.8 (Di) Prevents Infections (30% of starch is hydrolysed) The bolus , formed is then pushed into the oesophagus by the action of the tongue. The tongue presses against the palate and pushes the bolus into the pharynx. This is called swallowing or deglutition Food is swallowed too quickly for all the starch to be reduced to maltose Ptyalin in the swallowed food continues its action for 15-20 min in the stomach before it is inactivated by the acid of the stomach dr. aarif
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  37. 37. DIGESTION IN STOMACH GASTRIC JUICEHCl PEPSINOGEN MUCOUS1. Stops the action of Pepsinogen HCl Pepsin Mucous andsalivary amylase. (Inactive) (Active) bicarbonates2. Provides the acidic forms amedium (pH 1.8) required to Pepsin protective layerconvert inactive pepsinogen Proteins Peptones + Proteoses on the mucosato active proteolytic enzyme of the stomachpepsin to prevent the3. It kills the germs that may action of HCl.enter along with the food.4. It helps to soften the foodRennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion ofmilk proteinsAfter digestion in the stomach, food is converted into a semisolid mass called chyme. Acidicchyme travels into the duodenum through the pyloric sphincter dr. aarif
  39. 39. BILEBile helps to neutralize the acidic chyme.Bile juice is a yellowish green liquid.It is made up of water, cholesterol, bile salts, bile pigments and phospholipids butno enzymes. Bile salts Bile PigmentsBrings about emulsification of fats, i.e., (bilirubin and biliverdin) are produced as abreaking down of the fats into very small result of breakdown of haemoglobin.micelles. They give colour to faecal matterBile also activates lipases dr. aarif
  40. 40. PANCREATIC JUICE Amylase acts on the starch to form disaccharides maltose . AMYLASES Starch pancreatic amylase Maltose alkaline medium Lipase with the help of Bile converts lipids into fatty acids and glycerol . LIPASES Lipids pancreatic lipase fatty acids + glycerol alkaline medium Nucleases in the pancreatic juiceacts on nucleic acids to form nucleotidesand nucleosides NUCLEASES . Nucleic Acids Nucleases Nucleotides + Nucleosides dr. aarif
  41. 41. PANCREATIC INACTIVE TRYPSINOGEN & CHYMOTRYPSINOGEN JUICE Inactive trypsinogen is converted to trypsin by enterokinase from intestinal juice. Enterokinase TRYPSINOGEN TRYPSIN dr. aarif
  42. 42. INTESTINAL Secretion of Secretion of brush = + JUICE Goblet cells border cells Succus Mucous Disaccharidasesentericus Dipeptidases Lipases Nucleosidases dr. aarif
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  45. 45. ABSORPTION Absorption is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph. It is carried out by passive, active or facilitated transport mechanisms. ABSORPTIONPassive Active Facilitated TransportAlong the conc gradient Against the conc gradient Same as passive butNo energy required energy required Requires the presence of some carrier substances like Na+Water, short chain fatty Glucose, galactose, Na+, Fructose, some aminoAcids, water sol vitamins Amono acids acids
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  50. 50. NUTRITIONAL IMBALANCEDEFICIENCY OVERINTAKEDeficiency disorder affects the structure Excess of nutrients is also harmfuland function of the part which depends Animal fats --- Cardiovascular diseasesupon that nutrient Proteins ---- cancer of large intestine Vit A / D ---- HypervitaminosisResults in Deficiency disorders dr. aarif
  52. 52. KWASHIORKOR-It is a protein deficiency disease. Commonly affects infants and children between 1 to 3years of age.SYMPTOMS:The common symptoms of Kwashiorkor are underweight, stunted growth, poor braindevelopment, loss of appetite, anaemia, protruding belly, slender legs and bulging eyes.Oedema of lower legs and face and change in skin and hair colour may also occur inKwashiorkor.CAUSES:The basic causes of the disease are:Protein-deficient or inadequate diet due to ignorance or povertyInfectious disease such as diarrhoea, measles, respiratory infections, intestinal worms,which weaken the child.CURE:The proteins are the building blocks of food, and are essential for growth and repair of thetissues and also for the body defence. Therefore, adequate amounts of proteins must bepresent in the diet. For normal health, daily diet should contain one gram of proteins per kg.body weight in the case of adults and two grams of proteins per kg. body weight in the caseof growing children. The sources of protein are cereals, pulses, meat, fish, milk, cheese,leafy vegetables, groundnut, peas and beans. dr. aarif
  53. 53. MARASMUSIt is a form of prolonged protein energy malnutrition (PEM). It affects infants under one year of ageCAUSES:Marasmus is caused by simultaneous deficiency of proteins and total food caloric value,that is, deficiency of all nutrients. It affects the infant if mothers milk is replaced too earlywith foods having low protein content and caloric value. This often happens when themother conceives before her infant is ready for weaningSYMPTOMS:Due to protein-deficient diet, stored fats and tissue proteins are used as sources of energy.This impairs physical growth and retards mental development. Subcutaneous fatdisappears, ribs become very prominent, limbs become thin and skin becomes dry, thin andwrinkled. There is emaciation (extreme leanness) and loss of weight. Digestion andabsorption of food stop due to atrophy of digestive glands and intestinal mucosa. This leadsto diarrhoea. There is no oedema, characteristic of KwashiorkorCURE:Diet with adequate proteins and proper calorific value should be given to the infants. dr. aarif
  54. 54. INDIGESTIONIt is a nonspecific term that includes a variety of upper abdominal complaints includingheart burn, regurgitation and dyspepsia (upper abdominal discomfort or pain).-These symptoms are due to gastro-oesophageal reflux disease. It occurs as aconsequence of acid reflux into the oesophagus from the stomach. This may occur due toa large meal or acid hyper secretion.-Some other factors include physical position such as lying down, bending over, increasedpressure on the stomach (tight clothes obesity) and loss of lower oesophageal sphinctertone.-Indigestion can be improved with avoidance of large meals, smoking, alcohol, fatty foodand weight reduction and taking antacids. dr. aarif
  55. 55. CONSTIPATIONIt is defined as decrease in the frequency of stools to less than one per week or difficultyin defeacation which may result in abdominal pain, distortion and a rarely perforation.Some contributory factors may include inactivity, low fibre diet etc.Specific causes of constipation may include affected colonic mobility due to neurologicaldysfunction e.g. diabetes mellitus, spinal cord injury.Constipation may improve with increased dietary fibres, increased fluid intake andexercises. dr. aarif
  56. 56. JAUNDICEThis is not a disease in itself, but is a sign of abnormal bilirubin metabolism and excretion.Jaundice develops when there is an abnormality at some stage in the metabolic sequencecaused by excess haemolysis of red blood cells with the production of more bilirubin thanthe liver can deal with, obstruction to the flow of bile from the liver to the duodenum(gall bladder stones) and abnormal liver function (hepatitis viruses).Bilirubin, produced from the breakdown of haemoglobin is usually conjugated. Thebilirubin is water soluble and can be excreted. (Conjugation is a process of adding certaingroups to bilirubin to make it water soluble).Unconjugated bilirubin is fat soluble and has a toxic effect on the brain cells. Serumbilirubin may rise to 40 to 50 μmol/l before the yellow coloration of skin and conjunctiva isseen (Normal value is 3 to 13 μmol/l).Effects of raised bilirubin include pruritus (itching) caused by the irritating effects of bilesalts on the skin, pale face, dark urine and whitish stool.There is no specific drug to prevent jaundice. Mainly, the treatment involves supportivecare, bed rest and treatment of cause. dr. aarif
  57. 57. CARBOHYDRATES1. Carbohydrates are chemically composed of carbon, hydrogen and oxygen.(These are polyhydroxyaldehydic or ketonic organic compounds.)2. They are the main sources of energy. Carbohydrates form more than half of our diet, butform only 1% of our total weight. This shows that they are primarily fuel foods and are rapidly oxidized to supply energy forbody activities. dr. aarif
  58. 58. Carbohydrates can be classified into 3 categories:Monosaccharides:These are made up of simple sugars like glucose and fructose which are found in fruits andhoney.Disaccharides:1. These are composed of two molecules of simple sugars.2. These include sucrose, lactose and maltose.3. Sucrose is found in sugarcane, lactose in milk; however, maltose doesn’t occur free innature.Polysaccharides:1. These are made up of a number of molecules of simple sugars.2. They include starch, glycogen and cellulose.3. Starch is present in staple foods such as rice, wheat, maize, jowar, potato etc.4. Glycogen is the main reserve food material of animal cells. It is also known as animalstarch. Glycogen is stored in the muscles and liver.5. Cellulose is found in green vegetables. It is an indigestible fibrous carbohydrate that isnecessary as roughage for the smooth movement of food through the alimentary canal.
  59. 59. PROTEINS1. Proteins are chemically composed of carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorous.2. Proteins are natural polymers that are ranked first amongst the chemical substancesessential for growth and maintenance of life.3. Each protein is made up of numerous monomers, the amino acids which are joinedtogether by peptide bonds.There are 22 amino acids, out of which eight are said to be essential amino acids as thesecannot be synthesized in the body. Animal proteins like meat, milk, egg, fish, etc. contain all the essential amino acids andhence are known as complete proteins.4. Proteins cannot be stored in the body. Excess of proteins are deaminated (broken down) inthe liver, to produce urea which is eliminated by kidneys (excretion).Functions:a. Proteins help in repair of wear and tear of the body.b. Proteins aid the formation of enzymes, hormones, antibodies etc.
  60. 60. FATS (LIPIDS)Fats are chemically composed of carbon, hydrogen and oxygen.They comprise of heterogeneous organic compounds which are insoluble in water but readilysoluble in non-polar organic solvents like ether, chloroform, benzene, etc. On hydrolysis,lipids yield fatty acids which are utilized by the living organisms.(The fats present in our diet, after being processed in the alimentary canal and liver aresupplied to the tissues as glycerides. Fats are also formed from glucose and amino acids.Thus, carbohydrates are fattening. This is why a lamb or pig fed on a starch-rich diet (gramsand cereals) puts on fat.)Fats are solid or liquid. The fats which are liquid at room temperature are known as oils. Fatsare the richest source of energy. These are present in butter, cream, nuts, meat, fish and egg-yolk.A normal person needs 10%-25% of fats in his diet. Athletes need more than 40% fats.Deficiency of fats causes dry and rough skin while excess of fats results in obesity, high bloodpressure and heart diseases.Functions:They protect the body from shocks and jerks.They form the cell membrane.They act as solvents for vitamins like vitamin A, D, E and K.They make food tasty and palatable.
  61. 61. MINERALSMinerals are inorganic substances required in very small quantities.Minerals have small molecules and do not require digestion.Various minerals are present in our diet.Some of these minerals are sodium, calcium, phosphorous, potassium, iron, iodine etc.Sodium, potassium and chloride ions maintain the osmotic balance of blood plasma. Theseare obtained from common salt, sea foods and leafy vegetables.Calcium and phosphorous are necessary for the development of bones, teeth, heart action,nerve action and clotting of blood. Pregnant women and children need more calcium.Sources of calcium are milk, eggs, fish and leafy vegetables.Iron is necessary for formation of haemoglobin. Lack of iron leads to anemia. Sources of ironare fish, liver, meat, tomatoes, cabbage, leafy vegetables etc.Iodine is necessary for the proper functioning of the thyroid glands (production ofthyroxine). Its deficiency leads to a disease of the thyroid called goiter. The sources of iodineare iodized salt and sea foods.
  62. 62. Name of the vitamin Source Effects of deficiencyVitamin A Liver, milk, egg yolk, Night blindness, dry scaly(Retinol) tomato, carrot and papaya skin, defective teethVitamin B1 Yeast, whole grains, milk, Beriberi, loss of appetite,(Thiamine) meat and green vegetables nerve disordersVitamin B2 Meat, milk, egg white, Loss of body weight, mental(Riboflavin) soyabean and green leafy confusion, rough skin of vegetables. exposed partsVitamin B3 Fish, meat, potato, green Skin irritation, mental (Niacin) leafy vegetables disorder (pellagra)Vitamin B12 Liver and green vegetables Megaloblastic anaemia, (Cynocobalamine) digestive disordersVitamin C Citrus fruits, tomato, Scurvy (disease of gums)(Ascorbic Acid) cabbage, amla delayed wound healingVitamin D Fish liver oil, milk, action of Rickets, tooth decay (Calciferol) sunlight on the skinVitamin E Wheat-germ oil, milk, meat Sterility, muscular(Tocopherol) and leafy vegetables disorderVitamin K Green leafy vegetables, Bleeder’s disease, clotting(Phylloquinone) tomatoes, cabbage disorder