3. digestion fact test Flashcards
what is the role of the mouth in the digestive system
carries out
physical breakdown (chewing by teeth which increases surface area)
chemical digestion (salivary amylase)
what is the role of the oesophagus in the digestive system
transports food (bolus) from mouth to stomach, facilitated by a wave of muscle contraction
what is the role of the stomach in the digestive system
carries out physical breakdown (contraction of muscular walls to churn the food), temporarily stores food, carries out chemical digestion (glands release proteases) and contains hydrochloric acid
what is the role of the liver in the digestive system
produces bile which contains bile salts. these facilitate lipid digestion due to emulsification
what is the role of the pancreas in the digestive system
secretes pancreatic juice into small intestine
juice contains proteases, lipases and pancreatic amylase
the juices are alkaline to help create optimum pH in ileum
what is the role of the large intestine (colon) in the digestive system
absorbs excess water and ions, contains a plethora of bacteria which produce certain vitamins
what is the role of the rectum in the digestive system
stores compacted, indigestible material (faeces) before it is removed from the body via the anus
what happens in the small intestine (ileum) in the digestive system
where chemical digestion and absorption of soluble food molecules takes place
how is the small intestine adapted to its functions
- villi and microvilli provide a very large surface area for diffusion of food molecules
- epithelium is one cell thick for reduced diffusion distance
- muscle in villi allows movement and increased contact with food molecules
- rich blood supply to maintain diffusion gradient
- lacteals to allow lipid transport
- epithelial cells have many mitochondria to produce ATP and co-transport proteins for active transport
what is physical digestion
breaking down large food molecules into smaller pieces, increases surface area for chemical digestion
what is chemical digestion
hydrolysis of large insoluble molecules into smaller soluble ones, completed by enzymes
what do endopeptidases do
hydrolyse peptide bonds between amino acids in central region of a protein molecule forming a series of peptide molecules
what do exopeptidases do
hydrolyse peptide bonds on the terminal amino acids of peptide molecules
what do dipeptidases do
hydrolyse bond between 2 amino acids of a dipeptide
what enzymes are involved in lipid digestion
lipase
where is lipase made and where does it work
made in pancreas
works in small intestine
what is the substrate which binds to the lipase
triglyceride
what is the product formed after lipase action
fatty acids and monoglycerides
what enzymes are involved in protein digestion
endopeptidases
exopeptidases
dipeptidases
where are endopeptidases made and where do they work
made in stomach and pancreas
work in stomach and small intestine
what substrate binds to endopeptidases
polypeptides
what product is formed from endopeptidase action
short chain polypeptides
where is exopeptidase made and where does it work
made in pancreas
works in small intestine
what is the substrate that binds to exopeptidases
polypeptides
