M&n Week 3: Ch. 7 Endocrine Physiology

Front 1

In addition to secreting insulin and glucagon, the eondocrin pancreas alos secretes which 3 hormones?

Back 1

1. Somatostatin
2. Amylin
3. Pancreatic polypeptide

Front 2

List the different cells of the islets of langerhans and what they secrete.

Which cells are located centrally?

Back 2

a-cells: glucagon
b-cells: insulin
d-cells: somatostatin
f-cells: pancreatic polypeptide

*B-cells are located centrally

Front 3

Which organ is exposed to the highest concentration of pancreatic hormones?

Why?

Back 3

Liver

Venous blood from the pancreas drains into the hepatic portal V

Front 4

The Vagal N stimulates the secretion of which pancreatic hormones?

Back 4

1. Insulin
2. Glucagon
3. Somatostatin
4. Pancreatic polypeptide

Front 5

Sympathetic stimulation results in the secretion of which hormones?

Back 5

1. Glucagon
2. Pancreatic polypeptide

Front 6

Sympathetic stimulation results in the inhibition of which hormones?

Back 6

1. Insulin
2. Somatostatin

Front 7

Describe the 2 storage pools of insulin granules.
What type of release pattern results from these separate stores?

Back 7

5% stored in readily releasable pool
95% stored in reserve pool and need to be chemically modified/physically translocated to be used

*Biphasic pattern of insulin release in response to stimulation of the B-cell by glucose

Front 8

List the 3 locations of insulin degradation?
Which one is the major site of degradation?

Back 8

1. Liver <--major site
2. Kidneys
3. Peripheral tissues

Front 9

Why is C-peptide used as an index of the secretory capacity of the endocrine pancreas rather than insulin?

Back 9

C-peptide has a longer half life (it is not degraded in the liver, like insulin)

Front 10

When do the 2 identifiable rhythyms of insulin release occur? (describe in period of minutes)

Back 10

First phase: 5-10 minutes
Second phase: 60 - 120 minutes

Front 11

Which nutrients stimulate the release of insulin?

Back 11

1. Glucose
2. Amino acids

Front 12

Which hormones regulate the release of insulin?

Back 12

1. Insulin (+)
2. GLP-1 (+)
3. Somatostatin (-)
4. Epinephrine (-)

Front 13

Which neurotransmitters regulate the secretion of insulin?

Back 13

1. Norepinephrine (-)
2. Acetylcholine (+)

Front 14

How is the regulation of K+ channels by ATP mediated?

Back 14

sulfonylurea receptor

Front 15

What is the major pathway in the mediation of insulin-stimulated glucose transport and metabolism?

Back 15

PI3-K activation
(phosphoinositide-3-kinase)

Front 16

How can exercise stimulate glucose transport independent of PI3-K?

Back 16

Pathway involving 5'-AMP-activated kinase

Front 17

List 4 hormones/neurotransmitters that amplify insulin secretion.

Back 17

1. CCK
2. ACh
3. GLP-1
4. Gastrointestinal peptide

Front 18

What is the effect of catecholamines on insulin secretion?

What type of mechanism is used?

Back 18

Inhibition

G-protein coupled receptors
(also used by somatostatin)

Front 19

Describe the immediate, early, moderate, and delayed effects of insulin.

Back 19

1. Immediate --> glucose transport
2. Early --> regulation of metabolic enzyme activity
3. Moderate --> enzyme synthesis
4. Delayed --> growth and cellular differentiation

Front 20

Which proteins facilitate the interaction of the insulin receptor with intracellular substrates by serving as a scaffold for recruitment of proteins?

Back 20

IRS proteins
(insulin-receptor substrates)

Front 21

Describe the insulin receptor.

Back 21

Heterotetrameric (2a, 2beta chains) linked by disulfide bond
a-chain = insulin binding
b-chain = tyrosine kinase activity

Front 22

Describe the 2 major pathways activated by insulin binding to its receptor.

What are the different roles of these pathways?

Back 22

1. PI3-K --> metabolic activity
2. MAPK --> proliferation, differentiation

Front 23

How is the number of insulin receptors modified?

Back 23

1. Exercise
2. Diet
3. Insulin
4. Other hormones

Front 24

How does chronic exposure to high insulin, obesity, and excess growth hormone effect the number of insulin receptors?

Back 24

Results in downregulation of insulin receptors

Front 25

How does insulin stimulate lipogenesis?

Back 25

Activation of acetyl-CoA carboxylase

Front 26

What type of physical conditions cause elevated insulin levels?

Back 26

1. High waist circumference/ high waist-to-hip ration
2. Excess visceral fat
3. High BMI
4. Sedentery lifestyle
5. High energy intake

Front 27

What are the consequences of the proliferative effects of chronic hyperinsulinemia?

Back 27

(influence vascular smooth muscle cells)
1. Hypertension
2. Atherosclerosis
3. Cardiovascular disease
4. Dyslipidemia

Front 28

Proglucagon is expressed in which 3 organs?

Which main products of proglucagon are expressed in these tissues?

Back 28

1. Pancreas --> glucagon
2. GI tract --> GLP-1
3. Brain

Front 29

Where is GLP-1 produced and what influences its production?

Back 29

Produced in the small intestine in response to high conctration of glucose in the intestinal lumen

Front 30

What is the effect of GLP-1 on insulin?

Back 30

Amplifies insulin release

Front 31

What is the effect of somatostatin on insulin and glucagon release?

Back 31

Inhibits both

Front 32

What are the principle target tissues for glucagon?

Back 32

1. Liver
2. Adipose tissue

Front 33

What is the MAIN physiologic effect of glucagon?

Back 33

Increase blood glucose by:
Stimulating de novo hepatic glucose via gluconeogenesis and glycogen breakdown

Front 34

What is the effect of glucagon on adipocytes?

Back 34

Activation of hormone sensitive lipase

Front 35

What type of meals stimulate the release of somatostatin produced by d-cells of the pancreas?

Back 35

1. High-fat
2. High-protein
3. High-carbohydrate

Front 36

What hormone inhibits somatostatin?

Back 36

Insulin
(d-cells located in periphery of b-cells)

Front 37

What stimuli result in the release of pancreatic polypeptide?

Back 37

1. Food
2. Exercise
3. Vagal stimulation

Front 38

Where is amylin stored?

Back 38

In b-granules along with insulin and C-peptide

Front 39

How does a meal affect plasma amylin concentrations?

Back 39

Increases plasma amylin

Front 40

What is the function of amylin?

Back 40

Works with insulin to regulate plasma glucose concentrations:
1. Inhibits post-prandial secretion of glucagon
2. Slows gastric emptying

Front 41

What concentration of amylin would you expect to find in a patient with Type 1 diabetes?

Back 41

Low or absent

Front 42

What is the most common pancreatic hormone-producing tumor?

Back 42

Insulinoma

Front 43

What is the effect of a lack of insulin on circulating fatty acids and amino acids?

Back 43

Increases level of circulating fatty acids and amino acids
(decreased inhibition of lipolysis and proteolysis)

Front 44

What is the earliest phyhsiologic indication of B-cell dysfunction in Type 2 diabetes?

What is the consequence of this defect?

Back 44

Delay in the acute insulin response to glucose

*Results in exessive rise in blood glucose, which then produces a compensatory and exaggerated second-phase hyperinsulinemic response

Front 45

What are the 3 main pathologic defects in Type 2 diabetes?

Back 45

1. Excessive hepatic glucose production
2. Defective B-cell secretion
3. Peripheral insulin resistance

Front 46

Can exercise decrease insulin resistance in patients with Type 2 diabetes?

Back 46

Yes

Front 47

What measurement is used to moniter glycemic control in patients with known diabetes?

Back 47

Hemoglobin A1C
(glycosylated hemoglobin)

Front 48

Which diabetic treatment increases tyrosine-kinase activity in insulin receptors?

Back 48

Biguanides
(enhance insulin-mediated glucose uptake in skeletal muscle and adipocytes)

Front 49

Which diabetic treatments delay the intestinal absorption of glucose?

Back 49

a-glucosidase inhibitors