DIGESTION SYSTEM (ALIMENTARY CANAL/TRACT)

P S G F Food Class M I B F Confimatory Tests

1. A lot of villi increase surface area for absorpsion. 2. Each villi has thin wall to enable diffussion on ffod. 3. Each villi has rich network of blood capillaries.

ORGAN FUNCTION

Mouth

1. Food is chewed and broken up into small pieces.

Oesophagus 2. Food is pushed through by alternating contraction & relaxation of oesophagus muscles

3. No food digestion takes place here.

Stomach b. Neutralise the alkaline property of saliva.

Liquid milk proteins rennin solid milk protein pepsin peptones

7. Digestion is completed in the small intestine.

Millon Reagent from White Precipitate to Dark Red Precipitate. Iodin from Brown to Blueblack. (on Heating) Benedict Solution from Blue to Brick Red on heating. Filter turns to Translucent Spots (grease spots)

The efficiency of Villi to absorb food is increased by:

2. Salivary gland secretes saliva which is alkaline contains enzyme called salivary amylase.3. Salivary amylase digests starch into maltose. Starch Salivary Amylase Maltose

1. Food is pushed through the oesophagus into stomach.

known as peristalsis movement.

1. Food is mixed with gastric juices in the stomach.2. Gastric juices contain: a) hydrochloric acid and b) enzymes (rennin and pepsin).3. Acid: a. Kills bacteria found in food.

c. Provide acidic medium of enzymatic action.4. Enzymes: Rennin coagulates milk to help action of pepsin.

Small Intestine

1. Small intestines has 2 parts: duodenum and ileum.2. Duodenum receives bile and pancreatic juice.3. Bile is produced by liver and stored in gall bladder. It flows through bile duct.4. Bile a. emulsifies fat (break large fatty globules into small droplets). b. Provide alkaline medium of enzymatic action.5. Pancreatic juice has 3 enzymes: pancreatic amylase, protease & lipase. Starch Pancreatic Amylase Maltose

Peptones Pancreatic Protease Amino Acids

Fat Pancreatic Lipase Fatty Acids & Glycerol

6. In ileum, enzyme digest maltose into glucose.

8. The digested food is ready to be absorbed through thins walls (villi) of small intestine into bloodstream.9. Final food products absorbed are Glucose, Amino Acids, Fatty Acids, Glycerol, Vitamins & Mineral Salts by the process known as Diffusion.

Large Intestine

1. Water is re-absorbed in the large intestine.2. Undigested food is stored in rectum and expelled from body through anus as faeces.

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