Endocrine Pancreas and Carb Metabolism Flashcards Preview

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Flashcards in Endocrine Pancreas and Carb Metabolism Deck (50)
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1

Active transport of glucose

Occurs in the intestine and kidney
- co transport via Na/glucose

2

Passive transport of glucose

- GLUT1: fetal tissues, erythrocytes
- GLUT2: renal tubular cells, liver, beta cells
- GLUT3: neruons --> diffusion with high affinity, even at low bg concentrations
- GLUT4: insulin-regulated

3

Insulin-regulated glucose transport

Present in:
- adipose
- muscle
- heart
--> inserts into membrane when activated by insulin

4

GLUT4 is not present in what tissues?

- brain
- liver

5

Secretions of the endocrine pancreas

Interstitial fluid --> capillaries --> portal vein --> liver --> rest of the body

6

Insulin structure

Polypeptide
- C peptide: connecting peptide, secreted with insulin and directs fold of insulin

7

_____ can be used as a marker for endogenous insulin

C-peptide

8

Insulin structure variations

- dogs: 1 amino acid (same as pigs!)
- cats: 4 amino acids
- horse: 2 amino acids
- cow: 3 amino acids

9

Insulin is stored in ______

Secretory granules

10

Insulin in the blood

Circulates mostly unbound
- half life in plasma: 6 min
- mostly cleared within 10-15 min
- degraded by insulinase in liver
- allows rapid turn on/off of insulin functions

11

Insulin is ______

Anabolic
- decreases bg
- facilitates tissue uptake of glucose, amino acids, fatty acids, K, Mg, P

12

Insulin stimulates _____

- glycogen synthesis
- lipogenesis
- protein synthesis and storage

13

Insulin inhibits ______

- glycogenolysis
- lipolysis
- protein catabolism

14

Insulin receptor binding

Results within seconds!!
- 80% of body's cells increase glucose uptake (muscle, adipose, NOT most neurons)
- immediate phosphorylation of glucose

15

Insulin helps transport glucose into the cell, ________ blood glucose

Decreasing

16

Glucose uptake via GLUT4

Insulin binding --> receptor activation
- translocation of intracellular vesicles with GLUT4 to cell membrane to facilitate glucose uptake into cells

17

What happens when insulin is no longer available?

Vesicles separate from cell membrane within 3-5 min and move back inside cell until needed again

18

Insulin is a requirement for glucose transport in all cells in the body, EXCEPT

- neurons
- intestinal epithelium
- renal tubular epithelium
- liver
- RBC
- leukocytes
- beta cells

19

Insulin binding increases cell membrane permeability to

- amino acids
- K
- P

20

Slower insulin effect

10-15 minutes
- decrease or increase activity level of intracellular enzymes
- continues for hours to days

21

Treatment of DKA with IV insulin

- decreases K in blood
- decreases P in blood
- could lead to hemolysis and death

22

Muscle in the presence of insulin

- absorbs glucose for immediate energy
- synthesizes glycogen for use later

23

Liver in the presence of insulin

- stimulates glycogenesis (glycogen synthesis)
- inhibits glycogenolysis (glycogen breakdown)

24

In the absence of insulin (between meals)

- only slightly permeable to glucose
- muscle is dependent on FAs for energy

25

In the presence of insulin (post-prandial)

- high insulin, bg concentration
- insulin increases permeability to glucose

26

____ is the preferential energy source during exercise

Glucose

27

Effects of insulin on liver carbs

Promotes glucose storage in the form of glycogen

28

Insulin ______ glucose uptake and retention

Enhances
- increases activity of glucokinase (hexokinase)
- decreases activity of phosphatase (would release glucose)

29

Insulin _____ glycogen synthesis enzymes

Activates
- increases glycogen synthase
- enzyme adds glucose to glycogen polymers

30

Insulin ______ breakdown of glycogen

Inhibits
- decreases activity of liver phosphorylase
- enzyme causes hepatic glycogen breakdown to glucose