Digestion and Absorption

Question 1

Two types of digestive enzymes are?

Answer 1

Luminal and Membranous

Question 2

Luminal enzymes are pretty self-explanatory

Answer 2

Membranous enzymes are those which are inserted into the membranes of cells linng the gut

Question 3

What are some of the barriers to absorption in the gut?

Answer 3

1) Unrestricted water layer
2) Glycocalyx
3) Microvilli membrane
4) Cytoplasm
5) Basolateral membrane
6) Basement membrane
7) Capillary Fenestrae

Question 4

Basal cells of the gut lie where?

Answer 4

In crypts…..stem cells move up the villi and differentiate as they do. How do the stem cells divide?——Assymetrically, one stays in the crypt to be another stem cell and one matures.

Question 5

Gut lining is sloughed off every 3 days

Answer 5

ok

Question 6

50% of calories in the American Diet are what

Answer 6

Carbs

Question 7

What starts carb digestion?

Answer 7

Salivary Amylase

Question 8

Salivary amylase does what

Answer 8

Hydrolyzes alpha 1,4 linkages to yield disaccharides (maltose, Maltotriose, and alpha limit dextrins (1,4 and 1,6))

Question 9

Alpha 1,6 dextrins are digested by what membrane proteins?

Answer 9

Glucoamylase (5%)

Isomaltase (95%)

Question 10

Alpha 1,4 dextrins are digested by what membrane proteins

Answer 10

Glucoamylase (60%)
Sucrase (20)
Isomaltase (20)

Question 11

Maltotrose digested by what membrane proteins

Answer 11

Basically the same as alpha 1,4 dextrin because it is also a 1,4 linkage
G- 25
Sucrase- 25
I_ 50

Question 12

Lactose carb digested by

Answer 12

Lactase

Question 13

Sucrose carb digested by

Answer 13

Sucrase

Question 14

Trehalose found in

Answer 14

Mushrooms….digested by trehalase

Question 15

KNOW…all of these carbs turn into glucose at least partially. Which ones also turn into galactose and Fructose

Answer 15

Lactose— glucose and galactose

Sucrose— glucose and fructose

Question 16

Glucose is absorbed primarily by what method?

Answer 16

Active transport

Question 17

The fact that glucose is absorbed by active transport means what about its abosorption in the absence of oxygen

Answer 17

Not much of it happens.

Question 18

SGLT-1

Answer 18

Luminal glucose absorption

Question 19

How does SGLT-1 work?

Answer 19

It binds 2 sodiums and either a glucose or a galactose and brings them into the cell. The sodium is then exported out of the enterocyte by a Na K ATPase, if this doesn’t work, SGLT-1 doesn;t work.

Question 20

Glut-5 brings in?

Answer 20

Fructose

Question 21

Most common carb enzyme deficiency?

Answer 21

Lactase

Question 22

Glut-2

Answer 22

transports glucose through the blood

Question 23

What starts protein digestion?

Answer 23

Pepsin

Question 24

Pepsin does what

Answer 24

Its an endopeptidase so it cleaves peptide linkages

Question 25

Trypsinogen is converted to trypsin by what enzyme>

Answer 25

Enterokinase

Question 26

What does it mean to say that trypsin is auto-catalytic

Answer 26

Once it is activated it activates more of itself

Question 27

Pepsin and pancreatic proteases break down protein into what three things:

Answer 27

Di and Tri- peptides, Large Peptides and Free Amino Acids

Question 28

Large peptides are then shunted to either the Di and tri peptides or free amino acid

Answer 28

ok

Question 29

Lipid soluble amino acids may leave via?

Answer 29

SImple diffusion

Question 30

Triglycerides are broken down by pancreatic lipase into

Answer 30

2 monoglyceride + 2 FFA

Question 31

What the hell does colipase do?

Answer 31

It is secreted with pancreatic lipase, it is not an enzyme. It allows pancreatic lipase to get in close enough to an emulsion droplet in order to act on it. Binds to the emulsion droplet and displaces the bile acid, then binds to the pancreatic lipase and anchors it to the droplet.

Question 32

What activates pro-colipase

Answer 32

Trypsin

Question 33

Micelles contain what

Answer 33

cholesterol, fatty acids, monoglycerides.

Question 34

The order of fat absorption

Answer 34

CCK---> Micelle---> Triglyceride re-esterification ---> Chylomicron ---> Lacteal

Question 35

What is a lacteal

Answer 35

Lacteals are the lymph vessels that take up fat

Question 36

Two routes by which water and electrolytes are absorbed

Answer 36

Transcellular and paracellular (tight junctions)

Question 37

All of the mechanisms for sdium absorption depend on what?

Answer 37

Na K ATPase

Question 38

Some chloride absorption is linked to HCO3- secretion. THis process occurs where

Answer 38

Colon

Question 39

Water absorbed mostly in small or large bowel

Answer 39

Small- leaky tight junctions here

Question 40

POMC signals for what and via what

Answer 40

POMC stimulation leads to low food intake and high metabolism. Stimulated via alpha MSH

Question 41

Hunger stimulates --- and ----- to increase food intake

Answer 41

NPY and AGRP

Question 42

Leptin does what

Answer 42

released from fat cells to downregulate food intake....fat people make a ton of leptin but they are insensitive to it. Leptin usually stimulates POMC (no more eating) and blocks NPY (hunger).

Question 43

Ghrelin secreted by

Answer 43

Stomach . It increases apetite.

Question 44

Peptide YY (PYY)

Answer 44

stimulates POMC

Question 45

Intestinal smooth muscle contraction stimulated by

Answer 45

Ach