nutrient digestion and absorption

Question 1

principle dietary constituents

Answer 1

carbohydrate
protein 
fat
vitamins
minerals 
water

Question 2

carbohydrate types

Answer 2

monosaccharides
disaccharides
polysaccharides

Question 3

monosaccharides

Answer 3

hexose sugars (6C) 
glucose, galactose, fructose

breakdown products of complex CHOs which are absorbed by small intestine

Question 4

disaccharides

Answer 4

2 monosaccharides linked by glycosidic bond

broken down to constituent monomers by brush border enzymes in small intestnie

Question 5

lactose

Answer 5

glucose and galactose (lactase)

Question 6

sucrose

Answer 6

glucose + fructose (sucrase)

Question 7

maltose

Answer 7

glucose + glucose (maltase)

Question 8

starch

Answer 8

plant storage form of clucose

hydrolysed by amylases (saliva, pancreas)

Question 9

cellulose

Answer 9

constituent of plant cell walls

dietary fibre (no enzymatic digestion in vertebrates - requires bacteria (cellulase))

Question 10

glycogen

Answer 10

animal storage form fo glucose

glucose monomers linked by alpha-1,4 glycosidic bonds

Question 11

how does glucose cross the small intestine lumen into blood

Answer 11

Na and Glc bind to SGLT1
change of configuration and Na and Glc enter cell
Na/K pump pumps Na into blood (gradient of Na pulls Glc into cell)
Glc accumulates in cell until conc higher than in bloodstream, then it enters bloodstream down gradient via GLUT-2

Question 12

what transporter does fructose use to enter cell from intenstine lumen

Answer 12

GLUT-5

Question 13

proteins

Answer 13

polymers of amino acids linked together by peptide bonds

Question 14

proteases/peptidases

Answer 14

enzymes which hydrolyse peptide bonds and reduce proteins/peptides to amino acids

Question 15

endopeptidases

Answer 15

work at inner amino acids

Question 16

exopeptidases

Answer 16

work on outer amino acids

Question 17

how are amino acids transported into blood stream

Answer 17

sodium coupled amino acid transporter

specific transporter can then let amino acid out cell into bloodstream