Digestive System

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Slide 1

The Human Digestive System

Slide 2

Slide 3

Oral Cavity

Chewing

Saliva moistens food

Saliva contains enzymes

Slide 4

Esophagus

Moves food to the stomach by peristalsis

Slide 5

Stomach

Sphincters control movement of food into and out of the stomach

Stomach glands release gastric juices

water, enzymes, mucus, acid

Most food moves on to the small intestine within 4 hours

Slide 6

Small Intestine

Liver and pancreas secrete enzymes into the small intestine

Digestion is completed

Nutrients are absorbed through the intestinal walls

Slide 7

Colon (Large Intestine)

Bacteria produce some vitamins

Vitamins absorbed into bloodstream

Water is reabsorbed

Feces move on to the rectum

Slide 8

Carbohydrate Digestion

Mouth

Salivary amylase breaks starch into sugar

Stomach

pH is too low for amylase to work

Small Intestine

Pancreatic juices neutralize stomach acids

Intestinal and pancreatic enzymes complete carbohydrate digestion

Slide 9

Protein Digestion

Mouth

Only mechanical digestion occurs

Stomach

Hormone gastrin signals stomach to secrete acid

Acid converts pepsinogen to protein digesting enzyme pepsin

Small Intestine

Pancreas secretes trypsin into small intestine

Trypsin and other enzymes secreted by small intestine digest protein into amino acids

Slide 10

Fat Digestion

Mouth and Stomach

Only mechanical digestion occurs here

Small Intestine

Bile from liver (stored in gall bladder) emulsifies fat

Lipase from pancreas splits fat into fatty acids and glycerol