Absorption

Question 1

examples of things that increase caloric demand

Answer 1

From least to greatest:

• digestion, min act
• increased activity
• trauma/surgery
• major op
• major burn

Question 2

Cals/g of

• carbs
• protein
• fat

Answer 2

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

Question 3

basal caloric requirement

Answer 3

1400Cal/day

Question 4

digestion/min act cal requirement

Answer 4

1560Cal/day

Question 5

moderate activity caloric requirement

Answer 5

2300Cal/day

Question 6

the glycemic index estimates a food’s effect on…

-what can change this

Answer 6

blood glucose and therefor insulin secretion

-how the food is prepared can affect this as well as what else you eat with it

Question 7

major dietary monosaccharides

Answer 7

• glucose

- fructose

Question 8

major dietary disaccharides

Answer 8

• maltose
• lactose
• sucrose

Question 9

major dietary polysaccharide

Answer 9

• starch

- amylose and amyloectin

Question 10

intestinal carbohydrate enzymes (5)

-one in the saliva

Answer 10

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

Question 11

alpha amylase

Answer 11

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

Question 12

sucrase

Answer 12

hydrolyzes the conversion of sucrose to fructose and glucose

Question 13

lactase

Answer 13

-hydrolyzes lactose into galactose and glucose

Question 14

isomaltase

Answer 14

• capable of cleaving alpha 1,6 linkages of amylopectin

- attacks limit dextrins

Question 15

maltase

Answer 15

catalyzes the hydrolysis of maltose to glucose

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

carbs in the intestine are absorbed via…

Answer 18

simple diffusion, facilitated diffusion, and active transport

Question 19

diffusion

Answer 19

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

Question 20

facilitated diffusion

-example

Answer 20

• 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

Question 21

Glut 4

Answer 21

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

Question 22

SGLT

-where

Answer 22

• sodium linked glucose transporter

- located in the intestinal mucosa and kidney brush border

Question 23

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

Answer 23

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

Question 24

how is glucose transported into most cells

-however in two places it is different

Answer 24

facilitated diffusion

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

Question 25

carbohydrate and other substances enter portal circulation by

Answer 25

-heading to the liver as their original destination

Question 26

type 1 diabetic response to increased blood glucose

Answer 26

• higher initial response to the same food

- stays higher for a longer amount of time

Question 27

complex vs simple carb effect on blood glucose

Answer 27

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

Question 28

effect of the hexokinase reaction

Answer 28

• 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

Question 29

glucokinase vs hexokinase

Answer 29

• 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)

Question 30

Activity of glucokinase

Answer 30

-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

Question 31

glucose uptake in pancreatic beta cells

Answer 31

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

Question 32

Mature onset diabetes of the young

Answer 32

• 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