Stomach, Duodenum and Ileum Flashcards
where is the enzyme pepsin created?
the gastric glands in the stomach
enzyme pepsin when reacted with protein?
protein —-pepsin—-> peptide
how does the contractions of the stomach wall help enzymes?
it causes mixing of the contents of the stomach, maximising contact between enzymes and food
what is pepsin’s optimum pH?
around 2 (an acidic pH)
how are the conditions in the stomach made acidic?
due to the release of hydrochloric acid by the gastric glands
how does the stomach stop hydrochloric acid from burning through the stomach?
it is covered by a mucus lining
what is the two main functions of hydrochloric acid?
- to optimise pH levels for pepsin
- to kill bacteria and fungi in the food we eat
where do digestion and absorption happen?
in the small intestine (digestion only happens in the duodenum)
where is the final site of chemical digestion?
the duodenum
what enzymes do the pancreas make?
- trypsin
- amylase
- lipase
where does the pancreas secrete its enzymes?
the duodenum
enzyme trypsin when reacted with protein?
protein —-trypsin—-> peptide
enzyme amylase when reacted with starch?
starch —-amylase—-> maltose
enzyme lipase when reacted with lipids?
lipid (fat) —-lipase—-> glycerol + 3 fatty acids
which enzymes does the duodenum wall produce and secrete into the duodenum?
- maltase
- peptidase
enzyme maltase when reacted with maltose?
maltose —-maltase—-> glucose
enzyme peptidase when reacted with peptide?
peptide —-peptidase—-> amino acids
where is bile produced?
the liver
where is bile stored?
the gall bladder
where is bile released into after being stored?
the duodenum (through the bile duct)
what are the two functions of bile?
- neutralises stomach acid - enzymes in the duodenum work best at 7-8
- emulsifies lipids - breaks down large droplets into smaller droplets, increasing surface area for lipase to digest the fats
where does absorption happen?
in the ileum
how are small soluble molecules absorbed into the villi?
- diffusion
- active transport
how is the ileum adapted to increase the rate of diffusion?
- large surface area - folding of ileum, villi and microvilli (folds on the surface of cells lining the villi)
- short diffusion distance - the villi walls are one cell thick
- high concentration gradient - provided by capillary network and lacteals removing absorbed molecules
