Digestive System

Question 1

Mouth

Answer 1

mechanical digestion: mastication

chemical digestion: salivary amylase breaks down starch into disaccharides

Question 2

Oesophagus

Answer 2

made up of circular and longitudinal muscle, carries food from the mouth to the stomach via peristalsis.

Question 3

Stomach

Answer 3

has oblique, circular and longitudinal muscle layers. contains gastric juice (HCl + mucosa + enzymes) to aid in digestion.
mechanical digestion: churning via waves of muscular contraction.
chemical digestion: gastric protease (pepsin) breaks down proteins into polypeptides.

Question 4

Small Intestine

Answer 4

lined with mucosa and villi that absorb the nutrients.
contains intestinal juice (enzymes), pancreatic juice (enzymes) and bile (from gallbladder) to aid in digestion and neutralise stomach acid. some alcohols and certain drugs are absorbed here.
mechanical digestion: bile salts emulsify lipids, muscular contractions.
chemical digestion:
(in the pancreatic juice)
pancreatic amylase further breaks down starch into disaccharides, pancreatic protease (trypsin) breaks down proteins into polypeptides, pancreatic lipase breaks down lipids into fatty acids and glycerol, nucleases digest DNA and RNA.
(in the intestinal juice)
amylase breaks down disaccharides into simple sugars, peptidase breaks down polypeptides into amino acids, lipase breaks down lipids to fatty acids and glycerol.

Question 5

Large Intestine

Answer 5

no digestion occurs here; only absorption of water takes place. no lining of villi, and no digestive juices, although a lot of mucosa is secreted. bacteria break down remains into vitamins which are then absorbed.