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Endocrine (updated 2016) > 12 Pancreas > Flashcards

Flashcards in 12 Pancreas Deck (49):
1

Where is insulin produced

β-cells of pancreas

2

What is the precursor to the active form of insulin

proinsulin

3

What are the two chains of insulin

Alpha chain and beta chain linked by disulfide bonds

(C-peptide is cut out of the proinsulin molecule but also secreted)

4

Is insulin similar across species

Yes; highly conserved

5

What fragment of the proinsulin molecule is used to monitor endogenous insulin secretion post-injection

C-peptide fragment

6

Why is the C molecule useful

released in equimolar amounts with insulin
Is a 'record' of endogenous secretion
Is a way of measuring endogenous insulin levels

7

What are the actions of insulin?

Glucose metabolism
1) facilitates glucose uptake by most tissues
- exceptions: RBCs, most of the brain, intestinal mucosa, lens of the eye, kidney tubules
2) facilitates glucose storage as glycogen
3) lowers blood glucose
4) fat metabolism
5) protein metabolism
6) mineral metabolism

8

What does insulin do to blood glucose levels? How?

lowers blood glucose by:
- transports glucose into cells by carrier-mediated facilitated diffusion
- converts glucose to glycogen in liver
- converts glucose to TGs in adipose
- inhibits gluconeogenesis in liver

9

What is glucose converted into in the liver

glycogen

10

What is glucose converted to in adipose tissue

Triglycerides

11

What does insulin do to the liver

inhibits gluconeogenesis

12

What does insulin do to fat metabolisim

inhibits hormone-sensitive lipase (decreases lipolysis)
Promote fat deposition
Triglyceride synthesis

13

What does insulin do to protein metabolism

Increase AA transport into cells
Increase protein synthesis
Synergizes with GH

14

What does insulin do to mineral metabolism

transports K+ into cells

15

Is insulin anabolic or catabolic

anabolic (builds things up)

16

How is glucose metabolism maintained when blood glucose is high (hyperglycemia)

Increase glucose > increase insulin secretion > glucose cellular uptake (in muscle, fat)

decrease endogenous production of glucose > increased utilization of glucose (muscle & adipose cells) AND increased storage of glucose (in liver a glycogen), fat and aa arriving in the blood from GI tract

17

What are three major consequences of Insulin deprivation on CHO metabolisim

Glycosuria
Polyuria
Polydypsia

18

What are some consequences of insulin deprivation on fatty acid metabolism

lipolysis stimulated > formation of acetoacetic acid > formation of ketone bodies >
Ketoaciduria
Ketoacidosis: fruity breath > COMA > DEATH

19

What 3 conditions release insulin

High glucose
High AA
High FFA

20

What inhibits insulin

epinephrine

21

Where is glucagon produced

α-cells of pancreas

22

Is glucagon similar across species

yes; highly conserved in various species

23

What does glucagon do in the liver?
(5 things)

Increase gluconeogeneis
- increases every rate limiting enzyme
Increase glycogenolysis
- if glycogen is present it is mobilized
Decreases glyconeogenesis

Increase protein catabolism
Increase lipolysis

24

What does glucagon do in the liver

overall Increases glucose output

25

What stimulates glucagon secretion?

Decreased glucose
Elevated AA (also stimulates insulin)

26

What inhibits glucagon secretion?

High free fatty acids (FFA)

27

What does glucagon do to muscle

Increase FFA
(indirectly inhibits glucose uptake by muscle and fat)

28

What does glucagon do to adipose tissue

Promotes lypolisis

29

What is a normal blood glucose level 4mM

between 70-110mg/dl (90 is the mean)

below 70 = hypoglycemia
above 180 = hyperglycemia

30

What does somatostatin do to insulin and glucagon

inhibits release

31

What stimulates somatostatin

increased AA
glucose

32

What is the overall effect of somatostatin

Decrease glucose

decreased glucose transport across gut wall
- decreased gut blood flow

33

What hormone is hypoglycemic

insulin (only one)

34

α- cells of the pancreas make

glucagon (mobilizes glucose)

35

β-cells of the pancreas make

insulin (stores glucose)

36

δ-cells of the pancreas make

somatostatin (regulatory, inhibits endocrine pancreas)

37

What hormones are hypoglycemic?

ONLY insulin
there is no plan-B

38

gluconeogenesis

the synthesis of glucose from noncarbohydrate sources, such as amino acids and glycerol. It occurs primarily in the liver and kidneys whenever the supply of carbohydrates is insufficient to meet the body's energy needs.

stimulated by cortisol and other glucocorticoids and by the thyroid hormone thyroxine.

39

What are the major actions of insulin

↑ glucose transport into muscle & adipose cells
↓ blood glucose

↑ intracellular metabolic use of glucose
↑ glycogen synthesis in liver and muscle cells
↓ gluconeogenesis (in the liver)

↑ intracellular transport of aa & lipids and protein & triglyceride synthesis
↑ overall body growth (general effect)

40

How does insulin deprivation affect CHO metabolism?

insulin deficiency blocks glucose uptake & increases liver glycogenolysis > increase in serum glucose > increased glucose filtration in kidneys > glucose overload in kidneys

this causes:
glycosuria, polyuria, and polydypsia

41

define glycosuria (glucosuria)

glucose in the urine

when you loose glucose in the urine it drags water with it

42

polyuria

excessive urination

43

polydypsia

excessive thirst

44

Is glucagon anabolic or catabolic in terms of glycogen metabolism?

catabolic

it is used in situations where there is no fuel coming in but continued need for energy

45

If the body is hyperglycemic (high blood glucose) how does it normalize?

β-cells of pancreas release insulin
liver takes up glucose and stores it as glycogen
body / fat cells take in glucose from the blood
normal blood glucose levels are acheived

46

If the body is hypoglycemic (low blood glucose) how does it normalize?

α-cells of the pancreas release glucagon
liver breaks down glycogen and releases glucose into the blood
normal blood glucose levels are achieved

47

Where is somatostatin produced?

δ-cells of pancreas
GI tract
hypothalamus

(multiple forms 14 or 28 aa)

48

What happens to your blood sugar after you eat 10 chocolate chip cookies for lunch? How long does it take for insulin to be secreted?

blood sugar increases
insulin quickly released
- stored in pancreas and ready for release

49

You are on an 8-hr hike and you miss lunch. Does your blood sugar crash as you expend energy all day? What hormone would be increased in this metabolic situation?

no
glucagon