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Biochemistry MBS > Absorption > Flashcards

Flashcards in Absorption Deck (32):
1

examples of things that increase caloric demand

From least to greatest:
-digestion, min act
-increased activity
-trauma/surgery
-major op
-major burn

2

Cals/g of
-carbs
-protein
-fat

carbs= 4Cal/g
protein=4Cal/g
fat=9Cal/g

3

basal caloric requirement

1400Cal/day

4

digestion/min act cal requirement

1560Cal/day

5

moderate activity caloric requirement

2300Cal/day

6

the glycemic index estimates a food's effect on...
-what can change this

blood glucose and therefor insulin secretion
-how the food is prepared can affect this as well as what else you eat with it

7

major dietary monosaccharides

-glucose
-fructose

8

major dietary disaccharides

-maltose
-lactose
-sucrose

9

major dietary polysaccharide

-starch
-amylose and amyloectin

10

intestinal carbohydrate enzymes (5)
-one in the saliva

-alpha amylase (also secreted in the oral cavity)
-sucrase
-lactase
-isomaltase
-maltase

11

alpha amylase

attacks alpha glycosidic linkages of glucose polymers yielding maltoses and limit dextrin

12

sucrase

hydrolyzes the conversion of sucrose to fructose and glucose

13

lactase

-hydrolyzes lactose into galactose and glucose

14

isomaltase

-capable of cleaving alpha 1,6 linkages of amylopectin
-attacks limit dextrins

15

maltase

catalyzes the hydrolysis of maltose to glucose

16

why is cellulose, a polyglucose, not a good energy source?

-it has beta linkages and out enzymes are designed to only target alpha linkages

17

how does bacterial metabolism in the colon lead to clinical symptoms?

-this creates an osmotic effect where water rushes into the lumen of the intestine as well as H2 gas causing watery diarrhea and gas

18

carbs in the intestine are absorbed via...

simple diffusion, facilitated diffusion, and active transport

19

diffusion

-simply passing from one side of the membrane to the other without the use of energy or a chaperon

20

facilitated diffusion
-example

-this is getting across the membrane via a protein but without directly using ATP, typically a concentration gradient is utilized
-an example of this would be the Na-glucose co-transporter. Na goes down a concentration gradient, taking glucose with it

21

Glut 4

-involved in facilitated transport
-responsive to insulin in the blood
-increases the glucose intake of muscle, fat, and white blood cells

22

SGLT
-where

-sodium linked glucose transporter
-located in the intestinal mucosa and kidney brush border

23

how does insulin stimulate receptor function in muscle, fat, and white blood cells?

-when present, it increases the number of glucose receptors on the cell membrane

24

how is glucose transported into most cells
-however in two places it is different

facilitated diffusion
-except for in the intestine and kidney, it is active transport
-This is via the SGLT receptor

25

carbohydrate and other substances enter portal circulation by

-heading to the liver as their original destination

26

type 1 diabetic response to increased blood glucose

-higher initial response to the same food
-stays higher for a longer amount of time

27

complex vs simple carb effect on blood glucose

-simple carbs lead to a greater glucose spike in the blood

28

effect of the hexokinase reaction

-once inside the cell, hexokinase adds a phosphate to glucose using ATP
-it does this in order to keep the glucose concentration gradient down in the cell

29

glucokinase vs hexokinase

-hexokinase can P other hexoses, glucokinase is specific to glucose
-glucokinase is restricted to liver and pancreatic beta-cells; hexokinases are ubiquitous
-hexokinases, but not glucokinases, are inhibited by G6P (this way glucose uptake is limited in most cells when it needs it)

30

Activity of glucokinase

-has a high Km so that its activity becomes important when blood glucose concentrations get high - when this happens, the liver is still capable of removing glucose from the blood

31

glucose uptake in pancreatic beta cells

-glucokinase leads to increased production of ATP that acts on the potassium channel leading to insulin release

32

Mature onset diabetes of the young

-genetic deficiency in glucokinase (or transcription factor)
-leads to a defect in insulin secretion in response to elevated blood glucose
-in patients defective in this enzyme, the amount of ATP produced in response to elevated blood sugar is reduced, leading to a smaller effect on the ATP sensitive potassium chanel, less depolarization and less insulin secretion