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Flashcards in Pancreas Deck (40)
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1

What are the major cells in the Islets of Langerhans?

Alpha
Beta
Delta
PP
Epsilon

2

What is the function of alpha cells?

Make glucagon

3

What is the function of beta cells?

Make insulin

4

What is the function of delta cells?

Make somatostatin (SS14)

5

What is the function of PP cells?

Secrete pancreatic polypeptide

6

What is the function of epsilon cells?

Make ghrelin

7

What is the major function of insulin?

Energy storage (anabolic hormone)

8

What is the major function of glucagon?

Energy mobilization (catabolic hormone)

9

Describe the arrangement of alpha and beta cells.

Beta cells clustered in “core”; other cells in “mantle.”

Alpha cells surround beta cells in a sandwich formation and the line the outer capillaries.

10

How does blood flow in the Islets of Langerhans?

Blood feeds the center of the Islet and then
flows outward

11

Describe the processing of insulin.

Insulin is released with C-peptide and the C chain is cleaved off which is necessary for insulin to bind to its receptor

12

What is the function of C-peptide?

C peptide has a long half life in the blood and is used to measure pancreatic function

13

How does glucose outside of the beta cell stimulate the initiation of insulin release?

Transported into cell by GLUT-2, which has LOW affinity for glucose. Only when glucose is high will it transport.

14

What happens to glucose once it is transported into the beta cell?

Glucose will be turned into G6P only when the glucose levels are high as glucokinase has a low affinity for glucose.

G6P will be metabolized and it will generate ATP.

15

What happens with increased ATP levels in the beta cell?

Increased ATP will cause the cell's K+ channels to close and as a result, K+ will accumulate within the cell.

16

What is the function of sulfonylurea drugs?

They will also close the K+ channels in the beta cell, bypassing the glucose steps

17

What happens with increased K+ within the beta cell?

It will cause the cell to depolarize and Ca2+ channels to open.

18

What happens to the beta cell with the opening of the Ca2+ channels?

The Ca2+ influx will will cause the exocytosis of insulin vesicles

19

How do FFAs and AAs affect insulin release?

They will increase it as both can generate ATP within the beta cell as well

20

What is the biphasic insulin response following a meal?

1 - there is an initial insulin spike signaling the release of insulin that has already been docked at the membrane

2 - the rising slope after the drop signals newly synthesized insulin being released

21

What is the insulin receptor and how does it work?

It is a tyrosine kinase receptor and insulin binds receptor at alpha subunit and the beta subunit is autophosphorylated

22

What is the action of insulin in the muscle cell?

It allows for muscles to uptake glucose via GLUT4, otherwise, muscles cannot intake glucose.

23

What is the pathway for insulin action of the muscle cell?

-Autophosphorylation of receptor recruits IRSs (insulin receptor substrates).
- IRSs activate intracellular signaling cascades

RESULT: GLUT-4 inserted in membrane – glucose can enter cell

24

Which of the glucose transporters is glucose independent?

GLUT-1, 2, 3 are all insulin independent

25

What glucose transporter is glucose dependent?

GLUT-4 in muscle

26

What is the effect of insulin on the liver?

Promotes glycogen and TAG production Reduces glucose production/output

27

What is the effect of insulin on muscle?

Promotes glycogen and TG production and protein synthesis

28

What is the effect of insulin on fat?

Promotes TAG production, release of FFAs from chylomicrons, glycolysis

29

How is glucagon processed in the pancreatic alpha cell?

GRPP is cleaved from GLUC and is inactive

GLP-1 and 2 (Incretins) are not cleaved an inactive

GLUC is cleaved free and is active

30

How is glucagon processed in the intestinal L cell?

GRPP-GLUC is not cleaved and remains inactive as glicentin

The incretins GLP-1 and 2 are cleaved in the intestine and active.

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