Physio Exam 3 Lec 9

Front 1

Despite what we might think, NHE1 is not responsible for taking Na+(that enter the cell through NHE2 and 3) out of the cell, instead

Back 1

it is the Na/K pump that takes it out

Front 2

NHE1 is involved in housekeeping eg

Back 2

maintain intracellular pH

Front 3

NHE3 is more important for sodium transport and it is expressed only in villus

Back 3

cell not crypt

Front 4

NHE3 present by itself in a cell line it absorbs Na and secretes HCO3 in this case NHE3 is uncoupled. So NHE3 present in

Back 4

duodenum and first proximal part of jejunum

Front 5

When NHE3 is next t to HCO3/Cl exchanger, they are coupled and they both work to

Back 5

absorb NaCl. This is seen in intestinal epithelia, colon and distal part of ileum and epithelial lining gallbladder to concentrate bile

Front 6

Nutrient Assimilation

Back 6

refer to the overall process of digestion and absorption

Front 7

Digestion can occur in

Back 7

lumen, brush border, intracellularly in epithelial cells

Front 8

Pancreatitis would lead to malabsorption of

Back 8

proteins and carbohydrates

Front 9

Bile malabsorption and Vit 12 would result from

Back 9

Bile resection or disease

Front 10

Indigestible fibers

Back 10

Cellulose and pectins are not digested by mammalian enzymes but are fermented by the colonic bacteria (short chain fatty acids)

Front 11

a-Amylase cant break down

Back 11

the last bond, the point of branching in polysaccharides

Front 12

a-Amylase starts digestion in

Back 12

saliva but the main digestion is in duodenum by the pancreatic a-Amylase.

Front 13

Lactase=

Back 13

Lactose into galactose and glucose

Front 14

Gluco-amylase=

Back 14

glucose chains into smaller glucose segments

Front 15

Sucrase-isomaltase

Back 15

sucrose, maltose into fructose and glucose

Front 16

Galactose and glucose are absorbed by

Back 16

Glu/Na cotransporter (SGLT1).

Front 17

Oral rehydration targets

Back 17

oral rehydration because solution is a glucose sodium mixed, water follows this too and rehydration occurs

Front 18

Na/K pump is essential for Glu/Na cotransporter because it creates

Back 18

the Na gradient for Na to enter the cel

Front 19

Glucose passes to interstitial place along with

Back 19

fructose via Glut2.

Front 20

Glut 5 absorbs

Back 20

fructose

Front 21

Glucose-galactose malabsorption

Back 21

very rare hereditary disorder
-caused by mutations in SGLT1
-milder mutations cause a reduced transport activity and have been implicated in some cases of irritable bowel syndrome

Front 22

Lactose Intolerance

Back 22

common in adults
-normal developmental decline in lactase expression

Front 23

Congenital lactose Intolerance

Back 23

rare disorder, infants unable to digest breast milk due to deficiency of lactase

Front 24

Carboxypeptidases break
Endopeptidases
Aminopeptidases

Back 24

-breaks C ter
-breaks in between
-breaks Nter

Front 25

pepsin hydrolyzes

Back 25

aromatic aa

Front 26

Trypsin hydrolyzes

Back 26

Basic AA; produces peptides with c-ter basic aa

Front 27

Chymotrypsin

Back 27

Aromatic amino acids, leucine, methionine and glutamine: produces peptides with these a.a’s at c-terminus

Front 28

Elastase

Back 28

Neutral aliphatic amino acids: produces peptides with these at c-terminus

Front 29

Pepsin, trypsin, chymotripsin and elastase are all considered

Back 29

Endopeptidases

Front 30

Exopeptidases are

Back 30

Carboxypeptidase A and B

Front 31

Carboxypeptidase A

Back 31

Aromatic and neutral aliphatic amino acids at the c-terminus

Front 32

Carboxypeptidase B

Back 32

Basic amino acids at the c-terminus

Front 33

Zymogens are activated by____on the brush border

Back 33

enterokinase

Front 34

Peptides with 4 AA chains are broken down by

Back 34

brush border enzymes

Front 35

Short 2, 3 AA chains are absorbed by

Back 35

epithelial PepT proteins and a proton tags along

Front 36

Single AAs are absorbed via

Back 36

Na/AA transporter

Front 37

Hartnup disease

Back 37

Mutation in protein to absorb phenylalanine, but patients almost never have problems because cell is not depedent on a single AA. Treatment involves giving peptides to break down phenylalanine. This shows the redundancy of assimilation, meaning cell doesn’t depend on one AA. Cystinuria is the same as Hartnup

Front 38

Folate Absorption

Back 38

Specialized protein for absorption of Folate
Folate reduced to tetrahydrofolate
Specialized transporter in basolateral membrane takes folate out.
So two specialized transporters

Front 39

Cobalamin (B12) Absorption

Back 39

Absorption of B12 depends on the presence of intrinsic factor.
Absorption of B12 doesn’t involve transporter but receptor ligand based. B12 is the ligand bound to cobalamin. Cobalamin is secreted into interstitial space via vesicles

Front 40

Pernicious Anemia

Back 40

Absence of parietal cells
Antibodies against parietal cells
Anti-intrinsic factor antibodies
Impaired B12 absorption
Elevated plasma gastrin levels
Megaloblastic anemia

Front 41

Ca2+ absorption

Back 41

Ca2+ can be absorvbed para or intracellularly.
Gradient is not in favor of absorbing Ca2+. So absorption minimun. Vit D stimulates Ca2+ absorption. Gradient can change during pregnancy when Ca2+ in blood is reduced, Ca2+ is absorbed

Front 42

Iron absorption steps

Back 42

1) Fe2+ binds first to transferrin and the Fe2+ Tf complex then binds to the transferrin receptor. The complex is endocytosed
2)The low pH of the endocytic vesicle causes the Fe2+ to fall off the Tf. The Tf-receptor complex recycles to the apical membrane, where the Tf falls off
3)Fe2+ cotransports with H+ via DCT
4) Heme iron enters by unknown mechanisms. Heme Oxygenase releases Fe3+
5)Fe2+ transfers to mobiliferrin
6) Fe2+ leaves the cell and binds to a different transferrin in plasma