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HUMAN NUTRITION

dr. aarifThe materials which provide the two primary requirements of life, namely, energy andraw materials (matter) are called nutrientsThe processes which are responsible for providing energy are nutrition 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 is eliminated outside the body.

Thus, nutrition includes the processes like ingestion, digestion, absorption, assimilation and egestion (defecation).

dr. aarifNUTRITIONIngestionDigestionAbsorptionAssimilationEgestionthe process in which food is taken inside the body. This ingested food is then digested. process during which complex, non-diffusible and non-absorbable food substances are converted into simple, diffusible and absorbable substances by enzymes. . process in which the simple substances get diffused into the blood. Thus, the absorbed food is now carried to each and every tissue cell of the body where it is assimilatedthe process by which the protoplasm is synthesized into each cell of the body by utilizing simple food substances.process of the elimination of the indigestible remains of the food from the alimentary canal (defecation or evacuation)..

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dr. aarifHUMAN DIGESTIVE SYSTEMAlimentary CanalAccessory GlandsMouthBuccal CavityPalateTongueTeethPharynxNaso-PharynxOro-PharynxLaryngo-PharynxOesophagusStomachCardiacFundusPylorusSmall IntDuodenumJejunumIleumLarge IntCaecumColonRectumAnusSalivaryGlandsparotidSub lingualSub mandibularPancreas (Exocrine part)Liver

dr. aarifMOUTHUppermost Transverse slit-like opening of alimentary canalBounded by 2 fleshy lipsLeads to a large cavity called ORAL or BUCCAL CAVITYBUCCAL 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 membrane

Presence of : TONGUE, TEETH & SALIVARY GLANDS

dr. aarifTONGUE--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

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 teetha) Incisors - chisel shaped , for biting, cutting and gnawingb) Canines Pointed, used for ripping and shreddingc) Premolars for grindingd) Molars for grinding

3. DIPHYODONT : Teeth appear twice during lifetime

a) Decidious : 20 in number

b) Permenant : 32 in number 22(I)11(C)00(PM) 22(M)22(I)11(C)22(PM) 33(M)

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22(I)11(C)00(PM) 22(M)DECIDIOUS22(I)11(C)22(PM) 33(M)PERMENANT

CLINICAL APPLICATION : ROOT CANAL THERAPY

Root canal therapy is a multistep procedure in which all traces of pulp tissue are removed 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 remove the bacteria

Then the canals are treated with medication and sealed tightly. The damaged crown is repaired

SALIVARY GLANDS SUBLINGUAL GLANDSUBMANDIBULAR GLANDPAROTID

PHARYNX The buccal cavity leads in to the pharynx. It can be divided into 3 regions

NASOPHARYNX : lies behind the nasal cavities having the internal nares and Eustachian canals

OROPHARYNX : lies behind the buccal cavity and forms the passage for the bolus of food

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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dr. aarifOESOPHAGUS The oesophagus is 25 cm long, narrow, muscular tube connecting the pharynx to the stomach

It is lined by stratified squamous epithelium containing mucous glandsFood moves through the oesophagus due to rhythmic contractions of the longitudinal and circular muscles

This movement is called as PERISTALSIS

CLINICAL APPLICATION :CARDIA ACHLASIA

Failure of the sphincter to relax causes impediment for the food to pass through the oesophagus. Distention of oesphagus can lead to pain which is often confused with heart pain

CLINICAL APPLICATION :HEARTBURN

Failure of the sphincter to close after the passage of food in the stomach can cause the contents of the stomach to revert back in the oesophagus thereby leading to irritation of oesophageal wall causing a burning sensation called as Heartburn

dr. aarifSTOMACH

Sac like , J shaped, 25-30 cms long3 parts : i) Cardiac ii)Fundus iii) PyloricSphincters at both the ends of stomach

Cardiac Sphincter : prevents regurgitation of food back into the buccal cavity

Pyloric Sphincter : Regulates the passage of food into the duodenum FUNCTIONS : i) Churns the food ie breaks the food into smaller pieces which facilitates the mixing of food with gastric juice

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SMALL INTESTINELongest part of the Digestive system, it is 6m long and 2.5 cms broad . It is compactly coiled in the abdominal cavity The coils are held together by connective tissue membranes 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 the duodenumii) JEJUNUM : 2.5 m long and narrower than duodenumiii) ILEUM : Lower part of the small intestine 3.5 m long and opens in the largeintestine

dr. aarifLARGE INTESTINE

1.5 m long, arranged around the mass of small intestine in the form of a ? marki) CAECUM : small blind sac off the colon, Present at the junction of ileum and colon. At the junction is a ileocaecal valve that regulates passage of substances from the small to the large intestine. Caecum bears a small worm like vestigial organ called as appendix(functional in herbivores for the digestion of cellulose)COLON : Anterior region divided into 3 parts a) Ascending colon b) Transverse colon c) Descending colonRECTUM : Posterior region, about 15 20 cms long. The rectum has longitudinal folds and large blood vessels. Undigested matter called faecal matter is temporarily stored before egestion

dr. aarifANUS The rectum opens to the outside by the opening called ANUS . It is guarded by a sphincter. It removes undigested matter outside by a process known as DEFEACATION

dr. aarifHUMAN DIGESTIVE SYSTEMAlimentary CanalAccessory GlandsMouthBuccal CavityPalateTongueTeethPharynxNaso-PharynxOro-PharynxLaryngo-PharynxOesophagusStomachCardiacFundusPylorusSmall IntDuodenumJejunumIleumLarge IntCaecumColonRectumAnusSalivaryGlandsparotidSub lingualSub mandibularPancreas (Exocrine part)Liver

SALIVARY GLANDS SUBLINGUAL GLAND

SUBMANDIBULAR GLAND

PAROTID

The Salivary glands have 2 types of secretory cells :

Serous cells : produces a watery fluid containing enzyme SALIVARY AMYLASE or PTYALINMucous cells : produces mucous. It binds the food, makes it slippery so that it can be easily swallowed

dr. aarifLIVER

-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-bladder

Functions 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. aarifPANCREAS

It is a leaf-shaped gland lying in the gap between the duodenum and the stomach. It is a mixed gland because some part of it is exocrine in function, i.e. its secretion is carried by the ducts, while the other part is endocrine, i.e. its secretion is directly poured into the blood stream.

dr. aarifHISTOLOGY

dr. aarifHISTOLOGY OF STOMACH

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 the stomach.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 three parts:Muscularis mucosa: It is prominent and formed of outer longitudinal and inner circular muscles.Lamina Propria: It contains the gastric glands.Epithelium: It is columnar and folded to form gastric glands.dr. aarif

dr. aarifGASTRIC GLAND

These are simple, tubular, branched or un-branched glands, embedded in the lamina propria. Each is made up of the following 3 types of cellsCHIEF CELLS (PEPTIC CELLS):They are pyramid shaped Present deep in the base of the glands. Secretes enzyme pepsinogenPARIETAL 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)]MUCOUS CELLS:They are present in the neck region and secrete mucous.

dr. aarifHISTOLOGY OF SMALL INTESTINE

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HISTOLOGY OF LIVER

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dr. aarifHISTOLOGY 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 cells that secrete glucagon2. B or beta 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.

PHYSIOLOGY OF DIGESTION PHYSICAL CHANGES CHEMICAL CHANGES+breaking up of the food into smaller finer particles mastication, churning and peristaltic movementsChemical changes are brought about by the action of different enzymes.

The food eaten is insoluble and it cannot become a part of our body. The food undergoes many physical and chemical changes so that it is converted into the simple soluble absorbable form. This is absorbed into the mucosa cells of the alimentary canal and then diffused into the blood capillaries

dr. aarifDIGESTION IN BUCCAL CAVITY MASTICATION will break down the food in to smaller particlesTONGUE mixes the food with SALIVA secreted from the SALIVARY GLANDSSALIVA

PTYALINSTARCH MALTOSE(Poly) pH 6.8 (Di)(30% of starch is hydrolysed)LYSOZYME Anti-bacterialPrevents InfectionsThe 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 deglutitionFood is swallowed too quickly for all the starch to be reduced to maltosePtyalin in the swallowed food continues its action for 15-20 min in the stomach before it is inactivated by the acid of the stomach

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DIGESTION IN STOMACHGASTRIC JUICEHClPEPSINOGENMUCOUS1. Stops the action of salivary amylase.2. Provides the acidic medium (pH 1.8) required to convert inactive pepsinogen to active proteolytic enzyme pepsin3. It kills the germs that may enter along with the food. 4. It helps to soften the food Pepsinogen Pepsin (Inactive) (Active)

Proteins Peptones + Proteoses

HClPepsinMucous and bicarbonates forms a protective layer on the mucosa of the stomach to prevent the action of HCl.

Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteinsAfter digestion in the stomach, food is converted into a semisolid mass called chyme. Acidic chyme travels into the duodenum through the pyloric sphincterdr. aarif

dr. aarifDIGESTION IN SMALL INTESTINE

FOOD IN DUODENUM (chyme)

PANCREATICJUICEBILEINTESTINALJUICE

dr. aarifBILEBile 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 but no enzymes. Bile salts Brings about emulsification of fats, i.e., breaking down of the fats into very small micelles.

Bile also activates lipasesBile Pigments(bilirubin and biliverdin) are produced as a result of breakdown of haemoglobin.

They give colour to faecal matter

dr. aarifPANCREATIC JUICE AMYLASESAmylase acts on the starch to form disaccharides maltose. Starch pancreatic amylase Maltose alkaline medium

LIPASESLipase with the help of Bile converts lipids into fatty acids and glycerol. Lipids pancreatic lipase fatty acids + glycerol alkaline medium

NUCLEASESNucleases in the pancreatic juiceacts on nucleic acids to form nucleotidesand nucleosides. Nucleic Acids Nucleases Nucleotides + Nucleosides

dr. aarifPANCREATIC JUICEINACTIVE TRYPSINOGEN & CHYMOTRYPSINOGENInactive trypsinogen is converted to trypsin by enterokinase from intestinal juice. Enterokinase TRYPSINOGEN TRYPSIN

dr. aarifINTESTINALJUICE=Secretion of Goblet cellsSecretion of brush border cells+ Succus entericusMucousDisaccharidasesDipeptidasesLipasesNucleosidases

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dr. aarifSTOMACHBUCCAL CAVITYSMALL INTESTINELARGE INTESTINEBolusChymeChyle

ABSORPTIONActiveFacilitatedTransportPassivedr. aarifAbsorption 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. ABSORPTIONAlong the conc gradientNo energy required

Against the conc gradientenergy required

Same as passive but Requires the presence of some carrier substances like Na+ Water, short chain fatty Acids, water sol vitaminsGlucose, galactose, Na+, Amono acidsFructose, some amino acids

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dr. aarifNUTRITIONAL IMBALANCEDEFICIENCYOVERINTAKEDeficiency disorder affects the structure and function of the part which depends upon that nutrient

Results in Deficiency disordersExcess of nutrients is also harmful Animal fats --- Cardiovascular diseasesProteins ---- cancer of large intestineVit A / D ---- Hypervitaminosis

dr. aarifNUTRITIONAL DISORDERSPROTEIN ENERGY MALNUTRITIONKWASHORKORMARASMUS

KWASHIORKOR-It is a protein deficiency disease. Commonly affects infants and children between 1 to 3 years of age.SYMPTOMS:The common symptoms of Kwashiorkor are underweight, stunted growth, poor brain development, 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 in Kwashiorkor.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 the tissues and also for the body defence. Therefore, adequate amounts of proteins must be present 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 case of growing children. The sources of protein are cereals, pulses, meat, fish, milk, cheese, leafy vegetables, groundnut, peas and beans. dr. aarif

dr. aarifMARASMUSIt 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 mother's milk is replaced too early with foods having low protein content and caloric value. This often happens when the mother 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 fat disappears, ribs become very prominent, limbs become thin and skin becomes dry, thin and wrinkled. There is emaciation (extreme leanness) and loss of weight. Digestion and absorption of food stop due to atrophy of digestive glands and intestinal mucosa. This leads to diarrhoea. There is no oedema, characteristic of KwashiorkorCURE:Diet with adequate proteins and proper calorific value should be given to the infants.

dr. aarifIt is a nonspecific term that includes a variety of upper abdominal complaints including heart burn, regurgitation and dyspepsia (upper abdominal discomfort or pain). -These symptoms are due to gastro-oesophageal reflux disease. It occurs as a consequence of acid reflux into the oesophagus from the stomach. This may occur due to a large meal or acid hyper secretion.-Some other factors include physical position such as lying down, bending over, increased pressure on the stomach (tight clothes obesity) and loss of lower oesophageal sphincter tone.-Indigestion can be improved with avoidance of large meals, smoking, alcohol, fatty food and weight reduction and taking antacids. INDIGESTION

dr. aarifIt is defined as decrease in the frequency of stools to less than one per week or difficulty in 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 neurological dysfunction e.g. diabetes mellitus, spinal cord injury.

Constipation may improve with increased dietary fibres, increased fluid intake and exercises.CONSTIPATION

dr. aarifThis 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 sequence caused by excess haemolysis of red blood cells with the production of more bilirubin than the 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. The bilirubin is water soluble and can be excreted. (Conjugation is a process of adding certain groups to bilirubin to make it water soluble).

Unconjugated bilirubin is fat soluble and has a toxic effect on the brain cells. Serum bilirubin may rise to 40 to 50 mol/l before the yellow coloration of skin and conjunctiva is seen (Normal value is 3 to 13 mol/l).

Effects of raised bilirubin include pruritus (itching) caused by the irritating effects of bile salts on the skin, pale face, dark urine and whitish stool.

There is no specific drug to prevent jaundice. Mainly, the treatment involves supportive care, bed rest and treatment of cause.JAUNDICE

dr. aarifCARBOHYDRATES

1. 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, but form only 1% of our total weight. This shows that they are primarily fuel foods and are rapidly oxidized to supply energy for body activities.

Carbohydrates can be classified into 3 categories:

Monosaccharides:These are made up of simple sugars like glucose and fructose which are found in fruits and honey.

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 doesnt occur free in nature.

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 animal starch. Glycogen is stored in the muscles and liver. 5. Cellulose is found in green vegetables. It is an indigestible fibrous carbohydrate that is necessary as roughage for the smooth movement of food through the alimentary canal.

PROTEINS

Proteins are chemically composed of carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorous.

2. Proteins are natural polymers that are ranked first amongst the chemical substances essential for growth and maintenance of life. 3. Each protein is made up of numerous monomers, the amino acids which are joined together by peptide bonds. There are 22 amino acids, out of which eight are said to be essential amino acids as these cannot be synthesized in the body. Animal proteins like meat, milk, egg, fish, etc. contain all the essential amino acids and hence are known as complete proteins.

4. Proteins cannot be stored in the body. Excess of proteins are deaminated (broken down) in the 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.

FATS (LIPIDS)Fats are chemically composed of carbon, hydrogen and oxygen.They comprise of heterogeneous organic compounds which are insoluble in water but readily soluble 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 are supplied 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 (grams and cereals) puts on fat.)Fats are solid or liquid. The fats which are liquid at room temperature are known as oils. Fats are 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 blood pressure 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.

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. These are 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 iron are fish, liver, meat, tomatoes, cabbage, leafy vegetables etc.

Iodine is necessary for the proper functioning of the thyroid glands (production of thyroxine). Its deficiency leads to a disease of the thyroid called goiter. The sources of iodine are iodized salt and sea foods.

Name of the vitaminSourceEffects of deficiencyVitamin A (Retinol)Liver, milk, egg yolk, tomato, carrot and papayaNight blindness, dry scaly skin, defective teethVitamin B1 (Thiamine)Yeast, whole grains, milk, meat and green vegetablesBeriberi, loss of appetite, nerve disordersVitamin B2 (Riboflavin)Meat, milk, egg white, soyabean and green leafy vegetables.Loss of body weight, mental confusion, rough skin of exposed partsVitamin B3 (Niacin)Fish, meat, potato, green leafy vegetablesSkin irritation, mental disorder (pellagra)Vitamin B12 (Cynocobalamine)Liver and green vegetablesMegaloblastic anaemia, digestive disordersVitamin C (Ascorbic Acid)Citrus fruits, tomato, cabbage, amlaScurvy (disease of gums) delayed wound healingVitamin D (Calciferol)Fish liver oil, milk, action of sunlight on the skinRickets, tooth decayVitamin E (Tocopherol)Wheat-germ oil, milk, meat and leafy vegetablesSterility, musculardisorderVitamin K (Phylloquinone)Green leafy vegetables, tomatoes, cabbageBleeders disease, clotting disorder