UNIT 3 (topic 3) digestion and absorption Flashcards
how are the villus adapted for its function
- good blood supply (efficiently carries away products)
- thin outer layer (short diffusion pathway)
- epithelial cells have microvilli (increases SA)
- muscular walls that contract (maintain concentration pathway)
what is the function of the mouth
mechanically breaks down food through chewing
what is the function of the salivary glands
produce secretion that contains the enzyme amylase - hydrolyses starch to maltose
what is the function of the oesophagus
muscular contractions squeeze the food down from the mouth to the stomach (peristalsis)
what is the function of the stomach
stores and digests food, muscular sac with an inner layer that produces enzymes
what is the function of the liver
produces bile salts - emulsifies lipids and allows enzymes to act quickly on hydrolysing lipids
what is the function of the gall bladder
stores bile
what is the function of the pancreas
glands that secrete pancreatic juices containing protease, lipase and amylase
what is the function of the small intestine
long muscular tube, enzymes produced by walls of the ileum - walls fold into villi and microvilli
what is the function of the large intestine
absorbs water from the waste
what is the function of the rectum
stores faeces before it is egested out through the anus
what is the function of the anus
egestion of waste from the body
what are the ways in which food is physically digested
- food is mechanically broken down by structures like teeth and stomach walls
- gives a large SA for chemical digestion
what are the ways in which food is chemically digested
large, insoluble molecules hydrolysed into smaller, soluble ones by enzymes
which enzymes are used for carbohydrate digestion, where are they found and what do they break the molecule down to
- salivary amylase - made in the salivary glands - maltose
- pancreatic amylase - made in the pancreas and found in the small intestines - maltose
- maltase - made in the walls of the ileum - a-glucose
- sucrase - found in the small intestines - glucose and fructose
- lactase - found in the small intestine - glucose and galactose
what enzymes are used to digest proteins and where are they found
endopeptidase - stomach
exopeptidase - stomach
dipeptidase - stomach
what is the function of the endopeptidase
hydrolyses peptide bonds in the centre of the chain
what is the function of the exopeptidase
hydrolyses peptide bonds between terminal amino acids
what is the function of the dipeptidase
hydrolyses dipeptides into amino acids
what enzyme is used for lipid digestion, where it is found and the products
pancreatic lipase - found in the small intestines - produces monoglycerides and fatty acids
describe the stages of lipid digestion
- form large droplets (globules) in the digestive tract as triglycerides are not water soluble
- converted into smaller droplets (micelles) using bile emulsifying
- pancreatic lipase converts triglyceride into monoglycerides and fatty acids
- use facilitated diffusion to get into the epithelial cell as now polar
- SER synthesises the triglycerides
- packaged by Golgi body into a vesicle (chylomicrons)