Exchange and Mass Transport - Digestion

Question 2

What is digestion?

Answer 2

The breaking down by hydrolysis of large food molecules with enzymes to allow for absorption into the body

Question 3

What is the function of salivary glands in digestion?

Answer 3

to secrete saliva which helps lubricate food and contains salivary amylase for digestion

Question 4

What is the structure of the oesophagus and its function in digestion?

Answer 4

a smooth tube

transports food from the mouth to the stomach

Question 5

What is the function of the stomach in digestion?

Answer 5

store and digest proteins using peptidases

Question 6

What is the role of the pancreas in digestion?

Answer 6

to secrete pancreatic juice - containing peptidases, lipases, and pancreatic amylase

Question 7

What is peristalsis?

Answer 7

the contraction of muslces to move a bolus throughout the digestive system

Question 8

What is a bolus?

Answer 8

a lump of food that has been swallowed

Question 9

What is the function of the ileum in digestion?

Answer 9

to secrete digestive enzymes and absorb food molecules through villi and microvilli

Question 10

What is the function of the large intestine during digestion?

Answer 10

to reclaim water secreted by digestive glands via osmosis

Question 11

What bonds do lipases break when digesting lipids?

Answer 11

the ester bonds holding together the glycerol and fatty acid tails

Question 12

What are the 2 products of lipid digestion?

Answer 12

monoglyceride + 2 fatty acid tails

Question 13

What is a monoglyceride?

Answer 13

a glycerol molecule bonded to a single fatty acid chain

Question 14

What role do bile salts have in lipid digestion?

Answer 14

bile salts emulsify lipids into smaller droplets called micelles

Question 15

What is the effect of the emulsification of lipids?

Answer 15

the surface area of the lipids is increased, increasing the rate of digestion

Question 16

What are the 3 types of peptidases?

Answer 16

Endopeptidases

Exopeptidases

Dipeptidases

Question 17

What is the role of endopeptidases in digestion?

Answer 17

to break the peptide bonds in the central region of the protein, breaking the protein into several polypeptide chains

Question 18

What is the role of exopeptidases in digestion?

Answer 18

to break the polypeptide chains into dipeptides, starting at the terminals of the chain

Question 19

What is the role of dipeptidases in digestion?

Answer 19

to hydrolyse the peptide bond in dipeptides to release amino acids

Question 20

What makes dipeptidases different from endo/exopeptidases?

Answer 20

they are membrane bound peptidases - bound to the membrane of epithelial cells on the ileum wall

Question 21

What is the structure of a villus?

Answer 21

Lacteal in centre, surrounded by a blood capillary which is surrounded by a thin epithelium containing microvilli

Question 22

What is a lacteal?

Answer 22

composed of tiny lymphatic vessels that absorb fatty acids and glycerol from the ileum

Question 23

What do blood capillaries absorb in villi?

Answer 23

amino acids and glucose

Question 24

Once hydrolyzed, what happens to triglycerides during digestion?

Answer 24

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

Question 25

What are chylomicrons?

Answer 25

spheres of protein embedded-phospholipids containing cholesterol and triglycerides

Question 26

What is exocytosis?

Answer 26

the process of a molecule leaving a cell