[Physiology] Nutrient digestion and absorption

Question 1

Principal dietary constituents

Answer 1

Carbohydrate
Protein
Fat
Vitamins
Minerals
Water

Question 2

Monosaccharides

Answer 2

Hexose sugars (6C)

Breakdown products of complex CHOs which are absorbed by small intestine only

Question 3

Hexose sugars (6C)

Answer 3

glucose, galactose, fructose

Question 4

Disaccharides

Answer 4

Two monosaccharides linked together by glycosidic bond

Question 5

how are disaccarides broken down

Answer 5

Broken down to constituent monomers by brush border enzymes in small intestine (enterocytes in epithelial cells, in apical membrane)

Question 6

what are the components of lactose

Answer 6

glucose + galactose (lactase)

Question 7

what are the components of sucrose

Answer 7

glucose + fructose (sucrase)

Question 8

what are the components of maltose

Answer 8

glucose + glucose (maltase)

Question 9

what is starch

Answer 9

plant storage form of glucose

Question 10

what are the two glucose components in starch

Answer 10

a-amylose, amylopectin

Question 11

a-amylose

Answer 11

glucose linked in straight chains

Question 12

amylopectin

Answer 12

glucose chains highly branched

Question 13

what are glucose monomers linked by

Answer 13

α-1,4 glycosidic bonds

Question 14

what are α-1,4 glycosidic bonds hydrolysed by

Answer 14

amylases (saliva, pancreas)

Question 15

what is cellulose

Answer 15

constituent of plant cell walls

Question 16

what are the components that make up cellulose

Answer 16

linear chains of glucose monomers linked by β-1,4 glycosidic bonds

Dietary fibre

Question 17

what can the dietary fibre in cellulose be digested by

Answer 17

no enzymatic digestion in vertebrates - require bacteria

Question 18

what is glycogen

Answer 18

animal storage form of glucose

Question 19

what is glycogen made up of

Answer 19

Glucose monomers linked by α-1,4 glycosidic bonds

Question 20

what are the two membranes

Answer 20

apical membrane
basolateral membrane

Question 21

what are the apical membrane and basolateral membrane separated by

Answer 21

tight junction space complex

Question 22

transcellular transport

Answer 22

vesicle-mediated transport of macromolecules, such as plasma proteins, across the endothelial barrier

Question 23

paracellular

Answer 23

transfer of substances across an epithelium by passing through the intercellular space between the cells

Question 24

vectorial transport

Answer 24

The transport of an ion or molecule across an epithelium in only one direction (e.g. absorption of nutrients in the gut). Vectorial transport requires that transport proteins are nonrandomly distributed between the apical and basolateral plasma membrane.

Question 25

when starch/glycogen is broken down by amylase what is it broken down into

Answer 25

maltose, sucrose, lactose

Question 26

how does Na and glucose enter the apical membrane

Answer 26

SGLT1 transporter

Question 27

how does glucose enter the cell following transport by SGLT1

Answer 27

GLUT-2 transporter

Question 28

how does sodium leave the cell following entry by SGLT1

Answer 28

sodium - potassium ATPase

Question 29

how does fructose enter the apical membrane

Answer 29

GLUT-5 transporter

Question 30

how does fructose go out the basolateral membrane following GLUT-5 entry

Answer 30

GLUT-2

Question 31

what do all three sugars leave the cell using

Answer 31

GLUT-2

Question 32

what transporter does glucose and galactose use for entry into the apical membrane

Answer 32

SGLT1

Question 33

what is a protein

Answer 33

Polymers of amino acids linked together by peptide bonds

Question 34

how does the chain length vary on different proteins

Answer 34

large variation of chain length

Question 35

what is often undergone by proteins

Answer 35

post translational modification

Question 36

what is an example of post translational modification for a protein

Answer 36

(addition of CHO = glycoprotein; lipid = lipoprotein)

Question 37

what are peptides

Answer 37

Small proteins, 3-10 amino acids in length

Question 38

what are proteases/peptidases

Answer 38

Enzymes which hydrolyse peptide bonds and reduce proteins or peptides to amino acids

Question 39

endopeptidases

Answer 39

acts on the on the interior amino acids within the protein, not on the terminal ones. - used in water hydrolysis

Question 40

exopeptidases

Answer 40

exopeptidase is any peptidase that catalyzes the cleavage of the terminal (or the penultimate) peptide bond

Question 41

what are the two types of exopeptidases

Answer 41

aminopeptidase carboxypeptidase

Question 42

aminopeptidase

Answer 42

Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or peptide substrates

Question 43

carboxypeptidase

Answer 43

protease enzyme that hydrolyzes a peptide bond at the carboxy-terminal end of a protein or peptide

Question 44

how does an amino acid enter the apical membrane

Answer 44

enters alongside sodium on SAAT1

Question 45

how does an amino acid leave basolateral membrane

Answer 45

independent of sodium sodium leaves via sodium potassium ATPase