Process of digestion

Subject : ScienceStd : VIII

Tamilnadu state board syllabus

PROCESSOF

DIGESTION

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M.Kohila,M.A.,M.PHIL.,B.A.B.ED

Sec.Gr.Teacher,S.M.R.V.H.S.S.,

VADASERY,NAGERCOIL,

KANYAKUMARY DISTRICT,TAMILNADU-629001

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Kohila.nexo.com


Slide No.

Content1 Lesson title2 Author - Address3-5 Content6 Organs of digestive system7 Animations - links8 Digestive system of HUMAN BEING9 Digestive system of HUMAN BEING – Animation10 Mouth11 Tongue12 Salivary glands13 Salivary glands - Animation14 Pharynx and Oesophagus15,16 Stomach17 Stomach - Animation

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Slide No.

CONTENT18 Small intestine

19 Liver & Gallbladder

20 Emulsification

21 Pancreas

22 Enzymes secretes in pancreas and their functions

23 Animation of food conversion in Duodenum

24 Enzymes secretes in small intestine and their functions

25 Functions of small intestine -Animation

26 Absorption of food

27 Absorption of food-Animation

28 Large Intestine

29 Large Intestine – Animation of egestion



Slide No. CONTENT30 Recapitulation Match the following 31 Evaluation32 Choose the correct answer33 Acknowledgement



LARGE INTESTINE

STOMACH

SMALL INTESTINE

MOUTH OESOPHAGUS

ORGANS OF DIGESTIVE SYSTEM

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ANIMATIONS

Digestive system of human being

Functions of small intestine

Salivary glands

Absorption of food

Stomach

Emulsification

Food conversion in Duodenum

Egestion in Large intestine

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Mouth


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DIGESTIVE SYSTEM OF HUMAN BEING

Human beings need nutrients to grow and function properly.They obtain them from food.The food is digested by the digestive system .

The digestive system consists of alimentary canal and digestive glands.

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Process of Digestion The process in which the complex and insoluble contents of food are converted into simpler and soluble substances, suitable for absorption and assimilation is called Digestion . Food is digested by the enzymes.


stomach

Mouth

Oesophagus

Salivary glands

Liver

Gall bladder

DuodenumPancreas

Small intestineLarge intestine

Anus

DIGESTIVE SYSTEM OF HUMAN BEINGAnimation

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•The mouth is the entrance for the digestive system.• Here the food is chewed to break it up into small pieces. •The floor of the mouth contains a tongue. •The jaws are lined by teeth in our mouth.• These are called incisors, canines, premolars and molars.•The teeth chew the food well.

MOUTH

Tongue

Teeth

Pharynx

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The tongue has several papillae or sensory buds. It is the organ for the sense of taste.

Large taste buds

Small taste buds

TONGUE

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There are three pairs of salivary glands . They are,

1. PAROTID: It is found at the back of the throat.

2. SUBMAXILLARY: It is found below the lower jaw bone.

3. SUBLINGUAL: It is found at the base of the tongue.

• Salivary glands secrete saliva.• It contains an enzyme called ptyalin. • This converts Starch into maltose.• Lysozyme present in saliva acts as an antibacterial agent.

SALIVARY GLANDS

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Parotid

Submaxillarysublingual

Parotid

Submaxillary

sublingual

SALIVARY GLANDS



Pharynx and Oesophagus

• Pharynx is a common passage for food and air.• It opens into the Oesophagus.• It extends up to stomach.



• Stomach is an extremely elastic bag .

• It can store very large quantities of food .

• Oesophagus communicate with the anterior portion of the stomach through cardiac opening which is guarded by cardiac sphincter muscles .

• The opening from the stomach into the deodenum is known as pylorus. It is guarded by pyloric sphincter muscles . It prevents the passage of food into the duodenum .

• The food stays in the stomach for some times for the action of the enzymes .


Continued….


• When the food is partly digested, the pyloric sphincter muscle relaxes periodically, releasing small quantities of partially digested food into the duodenum.

• Gastric glands are found on the wall of the stomach.

• They secrete gastric juice. This juice consists of enzymes , pepsin, renin and gastric lipase.

• Pepsin converts protein into peptones.

• Renin converts milk protein caseinogens into casein.

• Gastric lipase begins the digestion of fat. To view the animation of the functions please go to the next side.

- Continued

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Protein

PeptonesM

ilk protein

Caseinogen

Casein

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Gas

tric

juic

e

pepsinReninGastric lipase

FatFat

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• The stomach is followed by the small intestine.• It is divisible into 3 portions.• They are, Duodenum, Jejunum and Ileum.• In the region of duodenum, liver and pancreas are connected to the alimentary canal.

SMALL INTESTINE

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•Liver is the largest gland of our body.•It secretes bile and it is stored in gall bladder . •Gall bladder is attached to the bile duct . This duct opens into the duodenum.•Bile contains bile salts and bile pigments.•The bile salts lower the surface tension of water, thereby emulsifying and saponifying the fats.

LIVER & GALLBLADDER

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a

Liver

Gall bladder

Duodenum

Pancreas

EMULSIFICATION

• Pancreatic lipase can not react directly on fat.• The bile salts reduce the surface tension of water and can change the fat into creamy liquid with tiny particles.• The pancreas lipase reacts with tiny lipid particles


Bile saltsPancreatic lipase


1. Pancreas is a leaf like digestive gland .2. It secretes pancreatic juice .3. It opens into the duodenum through a pancreatic duct.4. It secretes five enzymes.5. They are Trypsin , Carboxy peptidase, Chymotrypsin,

Pancreatic amylase, Pancreatic lipase.

PANCREAS

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pancreatic duct.


Enzyme ConversionTrypsin Converts protein and

peptons into polypeptides.

Corboxy peptidase Converts polypeptides into amino acids .

Chymotrypsin Digests milk protein.

Pancreatic amylase Converts starch into maltose

Pancreatic lipase Converts emulsifide fat into fatty acids and

glyserol

ENZYMES SECRETE IN PANCREAS AND FOOD CONVERSION IN DUODENUM

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Duodenum

Pancreas

Corboxy peptidase

Pancreatic amylasePancreatic lipase

Tripsin

Polypeptides

Amino acids

MilkProtein

Digested milk

protein

Starch

Chymotrypsin

Maltose

Protein,Peptones

Polypeptides

Fatty Acids,

Glycerol

Animation of Food conversion in Duodenum

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CorboxypeptidaseChymotr

ypsinPancretic amylase

Pancreatic lipaseTripsin

Emulsified fat

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Name ConversionErypsin Converts peptones and

polypeptides molecules into amino acids.

Maltase Converts maltose into glucose.

Lactase Converts lactose into glucose.

Sucrase Converts sucrose into glucose.

lipase Converts emulsified fat into fatty acids and glycerol.

Fructase Converts fructose into glucose

ENZYMES SECRETE IN SMALL INTESTINE AND THEIR FUNCTIONS

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Peptones

Amino

acids

Polypeptides

Amino Acids

Maltose

Glucose

Fructose

Glucose

Sucrose

Glucose

Fat

Fatty acids

Glycerol

Lactose

GlucoseErypsinLipaseFructaseErypsinMaltaseSucraseLactase

Functions of small intestine Animation



Artery

Vein

• Absorbtion is done by the villi.• Ileum has numerous minute finger like projections called Villi.• It has a network of blood capillaries and lymph capillary or lacteal.• Glucose, amino acids, vitamins, minerals and water are absorbed by the blood capillaries.• Fatty acids and glycerol are absorbed by the lacteals.

ABSORPTION OF FOOD

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Blood capilary

Lymphatic vessel

Epithelium

GlucoseAmino Acids

VitaminsMinerals

Fatty AcidsGlycerol

Water

ABSORPTION OF FOOD - Animation



•Large Intestine consists of colon, rectum, and anus.• It absorbs water from faecal matter.

LARGE INTESTINE

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colon

Rectum

AnusEgestion is the process of removal of faecal material from the large intestine through anus.

LARGE INTESTINE – Animation of Egestion



Match the followingClick on the names to match it with the correct organs

Liver

Pancreas

Gall bladder

Duodenum

Stomach

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RECAPITULATIONClick here for TAMIL version

Evaluation

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Choose the correct answer

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1. ________________ is the entrance for the digestive system.

5. _______________ is an extremely elastic bag.

2. There are ______________ pairs of salivary glands.

3. _______________ is found at the back of the throat.

4. _______________ is the common passage for food and air.

(a) Liver

(c) Pharynx

(c ) Mouth(b) Stomach

(a) Four (b) three (c) Five

(a) Parotid gland

(b) Submaxillary gland

(c) Sublingual gland

(c) Liver(b) Stomach(a) Oesophagus

(b) Oesophagus(a) Duodenum


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Process of digestion