Exchange and Mass Transport - Digestion Flashcards
What is digestion?
The breaking down by hydrolysis of large food molecules with enzymes to allow for absorption into the body
What is the function of salivary glands in digestion?
to secrete saliva which helps lubricate food and contains salivary amylase for digestion
What is the structure of the oesophagus and its function in digestion?
a smooth tube
transports food from the mouth to the stomach
What is the function of the stomach in digestion?
store and digest proteins using peptidases
What is the role of the pancreas in digestion?
to secrete pancreatic juice - containing peptidases, lipases, and pancreatic amylase
What is peristalsis?
the contraction of muslces to move a bolus throughout the digestive system
What is a bolus?
a lump of food that has been swallowed
What is the function of the ileum in digestion?
to secrete digestive enzymes and absorb food molecules through villi and microvilli
What is the function of the large intestine during digestion?
to reclaim water secreted by digestive glands via osmosis
What bonds do lipases break when digesting lipids?
the ester bonds holding together the glycerol and fatty acid tails
What are the 2 products of lipid digestion?
monoglyceride + 2 fatty acid tails
What is a monoglyceride?
a glycerol molecule bonded to a single fatty acid chain
What role do bile salts have in lipid digestion?
bile salts emulsify lipids into smaller droplets called micelles
What is the effect of the emulsification of lipids?
the surface area of the lipids is increased, increasing the rate of digestion
What are the 3 types of peptidases?
Endopeptidases
Exopeptidases
Dipeptidases
What is the role of endopeptidases in digestion?
to break the peptide bonds in the central region of the protein, breaking the protein into several polypeptide chains
What is the role of exopeptidases in digestion?
to break the polypeptide chains into dipeptides, starting at the terminals of the chain
What is the role of dipeptidases in digestion?
to hydrolyse the peptide bond in dipeptides to release amino acids
What makes dipeptidases different from endo/exopeptidases?
they are membrane bound peptidases - bound to the membrane of epithelial cells on the ileum wall
What is the structure of a villus?
Lacteal in centre, surrounded by a blood capillary which is surrounded by a thin epithelium containing microvilli
What is a lacteal?
composed of tiny lymphatic vessels that absorb fatty acids and glycerol from the ileum
What do blood capillaries absorb in villi?
amino acids and glucose
Once hydrolyzed, what happens to triglycerides during digestion?
now non-polar, so diffuse across membrane of epithelial cells
recombined into new triglycerides at SER
moved to golgi apparatus
associate with cholesterol and lipoproteins to form chylomicrons
exocytosis moves them into the lacteal
What are chylomicrons?
spheres of protein embedded-phospholipids containing cholesterol and triglycerides
What is exocytosis?
the process of a molecule leaving a cell
