THE HUMANDIGESTIVE SYSTEM

THE HUMANDIGESTIVE SYSTEM

Archana Das,Tangla

College,Tangla, Assam

The human digestive tract is a long, highly coiled, muscular tube that stretches from mouth to anus.From mouth to the anus, the human food tube or the digestive tract is about 9 meters long.

THE HUMAN DIGESTIVE TRACT

9meters

THE HUMAN DIGESTIVE TRACT MEASUREMENT

SPECIALIZED REGIONS WHERE DIGESTION TAKES PLACE

1. Food processing begins in the mouth.

2. The bite food is then swallowed and is moved through the pharynx to the esophagus.3. Then, food is mechanically and enzymatically digested in the stomach.

4. Most enzymatic digestion takes place in the small intestine.

5. The large intestine then eliminates wastes through anus.

SPECIALIZED REGIONS WHERE DIGESTION TAKES PLACE

MOUTH

PHARYNX

ESOPHAGUS

STOMACHSMALL

INTESTINELARGE

INTESTINEANUS

DIGESTIVE SYSTEM WITH OTHER ASSOCIATED ORGANS

DIGESTION AS IT OCCURS….

1. Food processing begins in the mouth.

2. The bite food is then swallowed and is moved through the pharynx into the esophagus.

3. Then, food is mechanically and enzymatically digested in the stomach.

4. The liver secretes bile.

5. The pancreas secretes digestive enzymes.

DIGESTION AS IT OCCURS….

6. Most enzymatic digestion takes place in the small intestine.

7. Nutrients are digested as they move the digestive tract.

8. Nerves and hormones regulate digestion.

9. Absorption takes place mainly through the villi of the small intestine.10. The large intestine eliminates wastes leading to the opening for the elimination of wastes called anus.

MECHANICAL PHASE – involves the breaking up of food into small pieces, pushing the food down the food tube, and mixing with it digestive juices

CHEMICAL PHASE – involves the further breaking up of the larger molecules of food into smaller molecules by the action of digestive enzymes

TWO PHASES OF DIGESTION

MECHANICAL DIGESTION starts in the mouth where four kinds of teeth tear the food into pieces:

Four kinds of teeth: 1. INCISORS – thin-edged for cutting food2. CANINES – are pointed used for tearing3. MOLARS & PREMOLARS – specialized for crushing and grinding

DIGESTION IN THE MOUTH

THE HUMAN TEETH INSIDE MOUTH

TEETH UPPER JAW

LOWER JAW

TOTAL

Incisors 2 ; 2 2 ; 2 8

Canine 1 ; 1 1 ; 1 4

Premolars

2 ; 2 2 ; 2 8

Molars 3 ; 3 3 ; 3 12

TOTAL: 32

THE PERMANENT DENTAL SET OF MAN

Salivary glands secrete saliva. This saliva contains the enzyme called salivary amylase.

This salivary amylase enables the chemical digestion of Starch into Maltose & Dextrin

CHEMICAL DIGESTION IN THE MOUTH

HUMAN SALIVARY GLANDS

STARCH Maltose

Salivary amylase

HOW MOUTH’S CHEMICAL DIGESTION IS DONE?

CARBOHYDRATES

Saliva makes food slippery and kills the germs by the action of

Lysozyme.

THE PROCESS OF PERISTALSIS

ESOPHAGUS – The canal that connects throat to the stomach.EPIGLOTTIS – It closes the opening to the nostrils during swallowingPERISTALSIS – A mechanism that pushes chewed food (bolus) and mixes it with digestive juices in stomachANTI-PERISTALSIS – results vomiting which prevents body from harmful substances that are ingested.

ESOPHAGUS ON CONDUCTING FOOD

It is a bag-like structure where protein part of food is digested.

Once food enters, the folds of stomach wall called Rugae, it starts secreting HCl

DIGESTION IN THE STOMACH

THE STRUCTURE OF THE STOMACH

The Parietal Cells of Gastric glands secret HCl and turns food into acidic

THE CHIEF CELLS secrete pepsinogen, an inactive enzyme precursor). When pepsinogen comes in contact with the acidic gastric juice, it becomes pepsin the main digestive enzyme of the stomach.

ENZYMATIC DIGESTION IN THE STOMACH

Digestion is completed in the small intestine and nutrients are absorbed by villi through its wall.The small intestine is about 5 to 6 meters in length and has 3 regions.

1. Duodenum2. Jejunum3. Ileum

DIGESTION IN THE SMALL INTESTINE

THE THREE REGIONS OF THE SMALL INTESTINE

Most chemical digestion takes place in the duodenum, the first layer of the small

intestine.

THE LAYERS OF THE SMALL INTESTINE

LIVER – The largest internal organ of the body and also one of the most complex organs which lies in the upper right. The liver secretes BILE

BILE – It is the fluid secreted by the liver which emulsifies fats

THE LIVER

THE LIVER SECRETING BILE

Secrets BILE and helps to maintain homeostasis by removing or adding nutrients to blood.Converts excess glucose to glycogen and stores it.Converts excess amino acids to fatty acids and ureaStores iron and certain vitamins.Detoxifies alcohol and other drugs and poisons.

FUNCTIONS OF A LIVER

PANCREAS is an elongated gland that secretes both digestive enzymes and hormones. They help to regulate the level of glucose in the blood. The enzymes secreted by the pancreas are:

Trypsin and Chymotrypsin.

THE PANCREAS

PANCREATIC LIPASE

Degrades fats

PANCREATIC AMYLASE

Breaks down almost all types of carbohydrates

except cellulose disaccharides

RIBONUCLEASE and

DEOXYRIBONUCLEASE

Split RNA and DNA to free nucleotides

Trypsin and Chymotrypsin digest polypeptides to dipeptides resulting

to:

THE PANCREAS RELEASES DIGESTIVE ENZYMES

1. Bile and digestive enzymes are released into the duodenum.

2. They act on the Chyme (a semi fluid mass of digested food expelled by the stomach into the duodenum)

3. Then enzymes produced by the epithelial cells lining the duodenum digest the major types of nutrients.

CHEMICAL DIGESTION IN THE SMALL INTESTINE

Chyme moves through the digestive tract by peristalsis. Nutrients in the chyme come into contact with enzymes that digest them.1. Carbohydrates are digested to monosaccharides2. Proteins are digested to amino acids.3. Fats are digested to fatty acids

and glycerols

THE DIGESTED NUTRIENTS

PROTEINS Amino acids

FATS Fatty acids & Glycerol

CARBOHYDRATES Monosaccharides

proteases

CHEMICAL DIGESTION OF COMPLEX MOLECULES

lipase

carbohydrases

SOME HORMONES THAT REGULATE DIGESTION

HORMONE SOURCE TARGET TISSUE

ACTION

Gastrin Stomach (mucosa)

Stomach (gastric glands)

Stimulates gastric glands to secrete

pepsinogen

Secretin Duodenum

(mucosa)

Pancreas

Liver

Signals secretion to

Stimulate bile secretion

Cholecystokinin (CCK)

Duodenum

(mucosa)

Pancreas

Gall bladder

Stimulates release of digestive

enzymes

Gastric Inhibitoy Peptide

(GIP)

Duodenum

(mucosa)

Stomach Decreases stomach churning

ABSORPTION is the process by which nutrients are taken up by cells of the food tube.Absorption takes place through the villi of the small intestine.Digested food like amino acids, sugars, fatty acids & glycerol diffuse into the cells of the villi.

ABSORPTION

THE STRUCTURE OF THE VILLUS

THE PROCESS OF ABSORPTION

Most of the digested food diffuse into capillaries and reach the blood, while fatty acids and glycerol diffuse into the lymph.

Through diffusion, digested food reaches the blood and lymph and undergoes a process called circulation.

The circulating fluids distribute the digested food to all the cells of the body.

Undigested food passes through the large intestine. It is called “large” because its diameter is greater than that of the small intestine. The large intestine is 1.3m in length.

THE LARGE INTESTINE ELIMINATES WASTE

THE STRUCTURE OF THE LARGE INTESTINE

ELIMINATION is the process of getting rid of digestive wastes materials that have not been absorbed from the digestive tract and did not

participate in metabolic activities.

ELIMINATION OF WASTE

Have a balance diet. Eat proper amount of food. Chew food well and eat slowly to facilitate digestion. Drink plenty of water. Balance your food with activities such as exercise.

TIPS FOR HEALTHY BODY

Vegetables and fruitsMilk and milk productsMeat including fishCereals such as riceOther healthy foods

Always Remember: The greatest wealth is your Health.

YOUR BALANCE DIET SHOULD INCLUDE:

ARCHANA DASTANGLA COLLEGE, ASSAM

Thanks !