digestion and absorption of nutrients

Question 1

what is the most consumed macromolecule?

Answer 1

carbohydrates

Question 2

why do polysaccharides need to be broken down into monosaccharides?

Answer 2

so they are small enough to be absorbed

Question 3

what breaks down these polysaccharides?

Answer 3

enzymes in the brush border of the small intestine

Question 4

how are the monosaccharides glucose and galactose absorbed at the apical membrane?

Answer 4

at the apical membrane of the small intestine, they are actively transported using the symporter sodium-glucose linked transporter.

Question 5

how is the monosaccharide fructose absorbed at the apical membrane?

Answer 5

fructose is transported via facilitated diffusion using GLUT5

Question 6

at the basal membrane, what does the GLUT2 transport?

Answer 6

it transports fructose, glucose and galactose across the epithelium.

Question 7

how are proteins broken down?

Answer 7

broken down by proteases into amino acids, dipeptides and tripeptides

Question 8

what are the two types of proteases and what do they do?

Answer 8

endopeptidases- break down internal peptide bonds which produces peptide fragments.

exopeptidases- break down of terminal peptide bonds which produces amino acids.

Question 9

name examples of exopeptidases

Answer 9

carboxypeptidases, aminopeptidases

Question 10

name examples of endopeptidases

Answer 10

trypsin, chymotrypsin, enterokinase

Question 11

how are amino acids transported into the intestinal epithelial cells?

Answer 11

they are co-transported with sodium across the apical (lumen side) membrane

Question 12

why are lipids harder to digest?

Answer 12

because they are insoluble

Question 13

what is emulsification

Answer 13

bile salts act on the surface of large fat droplets breaking them down into smaller fat droplets, increasing the surface area.