Chapter 8

Question 1

How do we digest carbohydrates in the form of starch?

Answer 1

• amylase starts digestion in mouth but denatured by stomach acid
• continues digestion in small intestine
• starch hydrolysed to maltose - maltase hydrolyses maltose into glucose

Question 2

How are lipids digested?

Answer 2

• bile from gall bladder emulsifies lipids = larger surface area
• lipids hydrolysed into fatty acids and glycerol and monglycerides by lipase
• monoglycerides, fatty acids and bile salts associate to form micelles (very small fat droplets)

Question 3

What is the function of endopeptaidase in digesting proteins?

Answer 3

• breaks bonds in middle of polypeptide chain o produce smaller versions
• stomch and small intesting

Question 4

What is the function of exopeptidases in digesting proteins?

Answer 4

• break bonds at end of polypeptide chain to produce single amino acids
• small intesting

Question 5

What is the function of dipeptidases in digesting proteins?

Answer 5

• digest dipeptides only

- epithelial cells and small intestine

Question 6

How does glucose get absorbed?

Answer 6

• sodium ions actively transported out of epithelial cells into the blood causing conc. gradient
• causes sodium to be diffused from s/intestine to epithelial cells (glucose attaches to sodium ions through co-transporter proteins)
• this causes conc. of glucose in in epithelial cell increases
• facilitated diffusion moves glucose into blood down conc. gradient

Question 7

How are lipids absorbed?

Answer 7

• monoglycerides and fatty acids transported to surface of epithelial cells - micelles keep large SA
• small so can fit through epithelial cells

Question 8

What is the function of micells in absorption of monoglycerides and fatty acids?

Answer 8

• made from bile salts stuck to monoglyceides and fatty acids
• join onto monglycerides and fatty acids to keep them small so they can be absorbed

Question 9

How are amino acids absorbed?

Answer 9

• sodium ions actively transported out of epithelial cells into ileum creating a conc. gradient
• they then diffuse back into epithelial cells through sodium-dependant transporter proteins taking amino acids with them