Exchange sunstances with their environment
what are some adaptations to increase SA:V ratio?
villi and microvilli - absorption of digested food
alveoli and bronchioles - gas exchange
spiracles and tracheoles - insect gas exchange
gill filaments and lamellae - fish gas exchange
Thin wide leaves - plant gas exchange
many capillaries - capillary network
Explain digestion of carbohydrates - what enzymes are used? where?
Amylases and membrane-bound disaccharidases
Amylase produced by Pancreas and salivary glands
Hydrolyses polysaccharides into maltose by hyrolysing glycosidic bonds
Explain digestion of proteins - what enzymes and where?
Endopeptidases - hydrolyse peptide bonds between amino acids in the middle of the chain
Exopeptidases - hydrolyse peptide bonds at the end of a chain
membrane bound dipeptidases when there is only two amino acids left
Explain the digestion of lipids - what enzymes and where ?
lipids digested by lipase and bile salts
lipase produced in the pancreas
hydrolyses the ester bond between triglycerides to form monoglycerides and fatty acids
bile salts produced in liver -emulsify lipids to form tiny droplets called micelles - increases the SA for lipase to act on
Describe the process of digestion of lipids
Lipids are coated in bile salts (made in the liver and released from the gall bladder) causes them to split up into droplets creating a larger surface area - faster hyrolysis action by lipase
what are micelles
water soluble vesicles formed of the fatty acids, glycerol, monoglycerides and bile salts
they deliver fatty acids, glycerol and monoglycerides to the epithelial cells of the ileum for absorption
Describe absorption
happens in small intestine
ileum wall covered in villi - thin walls and epithelial cells are covered in microvilli
Maximise absorption by increasing the SA and decreasing diffusion distance
Monosaccharide and amino acid absorption
By co transport