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S&F 4 test 1 > McCumbee - Endocrine Pancreas > Flashcards

McCumbee - Endocrine Pancreas Flashcards

1
Q

Endocrine cells account for less than 2% of the total pancreatic mass, are organized in discrete clusters called _________

A

Islets of langerhans

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2
Q

Beta cells in the islet of langerhans secrete __

A

Insulin

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3
Q

Alpha cells in the islet of langerhans secrete

A

Glucagon

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4
Q

Insulin is packaged into secretory granules as _______

A

Proinsulin

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5
Q

The secretory granules that carry proinsulin also contain prohormone-converting enzymes that cleave proinsulin into? ___- and ___

A

Insulin

C peptide

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6
Q

What is the half life of insulin (circulatory half life)

A

5-8 minutes

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7
Q

The ______ is the principal site of insulin degradation

A

Liver

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8
Q

Hormones released by the intestines during a meal that stimulate glucose-dependent insulin secretion

A

Incretins

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9
Q

What are the causes of insulin release during a meal? (X3)

A

Glucose

Amino acids (basic AA’s have most response)

Incretins

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10
Q

The principal incretins in humans are:

A

GLP-1

GIP

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11
Q

Thru what transport method is insulin eventually released from beta cells?

A

Exocytosis

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12
Q

Somatostatin _____ the Beta cell release of insulin

A

Inhibits

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13
Q

Exercise and stress inhibit insulin release. This effect Is mediated by sympathetic stim via _______ adrenergic receptors

A

Alpha2

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14
Q

This protein is part of the insulin signaling pathway and has many phosphorylatable tyrosines that are then able to be bound by various proteins with the SH2 domain, giving insulin a variety of functional capabilities

A

Insulin receptor substrate (IRS)

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15
Q

___________ terminate insulin signal transduction by dephosphorylating the insulin receptor, IRS proteins, and other proteins phosphorylated during signal transduction

A

Protein-tyrosine phosphatases

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16
Q

Signal intensity of insulin can be _______ by the phosphorylation of serine residues on the insulin receptors

A

Lessened

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17
Q

_____ is the most physiologically important stimulus for the release of glucagon

A

Hypoglycemia

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18
Q

The primary target of glucagon action is the _____

A

Liver

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19
Q

The period time during which the cell metabolism consists primarily of the nutrients of that meal

A

Absorptive state

Lasts about 4 hours

20
Q

Explain the GLUT2 transporters role in glucose levels.

A

GLUT2 is a low-affinity glucose transporter that moves glucose into and out of hepatic cells by facilitated diffusion. Post meal, when glucose levels are high, it transports glucose into the hepatocytes for storage. When glucose levels in blood are low, it does not move glucose into the cell because of its low affinity When blood glucose levels are lower, and the hepatocytes are making glucose, the GLUT2 transporters take glucose out of the cell and move it to the bloodstream.

21
Q

Insulin ______ glucokinase expression

A

Increases

22
Q

Glucose entering the liver during the absorptive state does what?

A

It is converted to glucose-6-phosphate by glucokinase

23
Q

By regulating key enzymes in the liver, insulin ____ (x6)

A

Promotes the storage of glucose as glycogen.

Promotes glycolysis

Inhibits glycogenolysis

Prevents release of glucose by keeping in G-6-P form.

Inhibits gluconeogenesis

Stimulates fatty acid synthesis during period of carb excess

24
Q

Liver glycogen peaks ______ to ___ hours after a meal

A

4 to 6

25
Q

What sort of enzymatic response will you get if you eat a meal that is high in protein content and low in carbohydrate content?

A

Pancreas releases glucagon and insulin

Insulin - because of AA’s in proteins

Glucagon - low glucose medium, prevents insulin induced hypo-glycemia by stimulating hepatic glycogenolysis and gluconeogenesis

26
Q

Glucose uptake by skeletal muscle during absorptive state is regulated by?

A

Primarily insulin

Lesser extent by blood glucose concentration

27
Q

What does insulin do to increase the glucose uptake by skeletal muscle in the absorptive state?

A

It stimulates the translocation of the GLUT4 transporter that are stored in the intracellular vesicles, increasing Vmax of transport.

28
Q

Insulin has a profound _________ effect on basal and hormonal stimulated lypolysis in fat cells

A

Inhibitory

Insulin acts by inhibiting hormone sensitive lipase inside adipocytes

29
Q

What does insulin do to increase transport of glucose to adipocytes?

A

Signals the translocation of the GLUT4 transporters

30
Q

Insulin has a stimulatory effect on fatty acid synthesis by stimulating?

A

Synthesis of lipoprotein lipase which breaks TAG’s to FA’s and glycerol

(Has to be done to get them in cell. Once in, combined w/ glycerol 3 phosphate to form IC TAG’s)

31
Q

Insulin has a profound inhibitory effect on basal and hormone stimulated lipolysis IN fat cells. Insulin acts by _______ hormone-sensitive lipase inside adipocytes.

A

Inhibiting

(Hormone sensitive lipase catalyzes breakdown of TAG’s in fat cells into FA’s and glycerol)

[epinephrine is most potent physiological stimulator of hormone-sensitive lipase activity]

32
Q

In the liver, insulin _____ ketogenesis

A

Suppresses

33
Q

Rate of ketogenesis increases as the rate of ______ increases

A

Rate of flux of FA into liver increases

34
Q

Insulin suppresses hepatic ketogenesis by ? (X2)

A
  1. Blocking lipolysis (insulin is a very strong inhibitor of hormone-sensitive lipase)
  2. Inhibiting carinitine acyltransferase (transfers fatty acids to mitochondria)
35
Q

The principal substrates for hepatic gluconeogenesis during a fast are: (x4)

A

AA’s and lactate (from skeletal muscle)

Lactate (from RBC’s)

Glycerol (from fat)

36
Q

Cortisol ______ protein catabolism

A

Promotoes

Important aspect of gluconeogenesis

37
Q

Insulin ______ protein catabolism

A

Inhibits

38
Q

Growth hormone levels increase w/in first 24 hours of a fast. What are the two effects on metabolism GH has that helps w/ fast

A

Stimulation of lipolysis

Inhibition of glucose uptake by skeletal muscle and adipose tissue (send it to more important muscles)

39
Q

Plasma glucose, FFA, and glycerol levels usually stimulate after about ___ days of a fast

A

3

40
Q

____ hormone from the thyroid regulates basal metabolic rate and is dropped after a fast that lasts from days to weeks?

A

T3

There is a 15-20% drop in basal metabolic rate in this kind of fast and T3 levels drop by half

41
Q

Glucose from blood enters brain thru?

A

Glucose transporters in the endothelial cells by facilitated diffusion

42
Q

Ketones enter the brain via?

A

Monocarboxylate transporters (MTC)

43
Q

Causes of hypoglycemia: (x6)

A
  1. Drugs that potentiate effects of insulin or interfere w/ gluconeogenesis
  2. Insulinomas
  3. Rapid gastric emptying in pt’s w/ grastrectomies
  4. Adrenal/pituitary insufficiency
  5. Liver dz
  6. Inborn errors of carbohydrate metabolism
44
Q

Hormones releases in response to hypoglycemia

A

Counterregulatory hormones

45
Q

What are some counterregulatory hormones (x4)

A

Glucagon

Epinephrine

GH

Cortisol

S&F 4 test 1 (22 decks)

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