Functions of GIT

Dr. Hazrat Bilal Malakandi, PTDPT (IPM&R,KMU), MSPT* (KMU)

• What is digestion?

• what is GIT? What are its parts?

• What are accessory organs of GIT?

Basic GIT Functions

• Primary function

– Movement of

nutrient

molecules from

the external

environment to

the internal

environment

• Done through the

processes of:

• Secondary functions

– Mass balance• Ensuring daily fluid

input and output are equal

– Protection• GI tract provides a

huge external surface for pathogens to gain entrance into the internal environment

Functions of GIT

• Ingestion of food

• Digestion of food

• Secretion of digestive juices

• Absorption of water, salts, vitamins and

end products of food digestion

• Excretion of waste products

• Helps erythropoiesis by secreting intrinsic

factor needed for vit. B12 absorption.

Functions of tongue

1. Speech

2. Taste

3. Chewing

4. Swallowing

5. Lingual lipase

6. Cleansing of teeth

7. Moistening of lips

Functions of Stomach

1. Storage

• Until food is processed in stomach and

intestine

• Limit = 1- 1.5 lit

2. Mixing (with gastric secretions)

• Unless semi fluid mixture: chyme

3. Absorption

– Poor absorptive area

• No villi

– Alcohol, some drugs (e.g. Aspirin)

4. Slow emptying

• At a rate suitable for digestion and

absorption in small intestine

Functions of Small intestine

• Two main functions

– Digestion

– Absorption

• Digestion

– 90 % of digestion occurs in small intestine

– Carbohydrates glucose

– Proteins Amino Acids

– Fats Fatty acid & glycerol

• Absorption

Function of colon

• Absorption of H2o and electrolytes from

chyme (by proximal ½).

• Storage of fecal matter until it can be

expelled (by distal ½).

Major Functions of the Liver

1. Carbohydrate metabolism: maintains blood sugar levels.

a. Low Sugars levels: (control- glucagon)

glycogenolysis glycogen > glucose

b. High sugars levels: (control- insulin)

glycogenesis glucose > glycogen

2. Lipid metabolism

a. Break down fats: lipolysis, beta oxidation

b. Synthesize cholesterol

c. Stores triglycerides

3. Formation and secretion of bile

4. Nutrient and vitamin metabolism

5. Inactivation of various substances

6. Synthesis of plasma proteins

7. Immunity

8. Storage of Vitamins (A, B12, D, E, and

K) and iron

Functions of Mucus

1. Lubrication

• Coats the wall of gut (prevents actual contact of food with gut wall)

• Low resistance for slippage

2. Protection

3. Adherent qualities

• Adherence of fecal particles

4. Resistant to digestion

5. Mild buffering properties

Functions of Saliva

1. Digestion i. Salivary Amylase

Secreted by salivary glands

ii. Lingual lipase Secreted by glands on the tongue

2. Articulation3. Moistening of food4. Mastication 5. Water regulation (thirst)6. Swallowing 7. Keeps mouth clean8. Neutralization of gastric acid

Relieve of heartburn

10.Protection from bacteriai. Wash away bacteria

ii. Wash away the food of bacteria

iii. Destroy bacteria

11. Tooth Protection

1. By neutralizing acid

2. By affecting mineral dissociation equilibrium by means of its calcium phosphate content.

3. Proline-rich proteins protect the tooth enamel and bind toxic tannins

Bile functions

– Digestion of fats

• Emulsification

– Large fat particles →small fat particles

– Absorption of fats

– Excretion

• Bilirubin

– End product of hemoglobin destruction

• Excess cholesterol