2-5-16-Endocrine Pancreas (Lopez)

Question 1

___ permits rapid cell-to-cell communication between alpha cells, beta cells, and alpha to beta cells

Answer 1

Gap junctions

Question 2

___ blood from the beta cells carries insulin to the alpha and delta cells

Answer 2

Venous

Question 3

Insulin is a ____ hormone made of 2 straight chains linked by disulfide bridges

Answer 3

Peptide

Question 4

___ has 4 peptides (signal peptide, A and B chains of insulin, and a connecting peptide (C peptide))

Answer 4

Preproinsulin

Question 5

___ does not have a signal peptide, the C peptide is still attached to insulin, disulfide bridges form in the ER (folded form of insulin), packaged in secretory vesicles in the golgi, and proteases cleave this during packaging

Answer 5

Proinsulin

Question 6

___ is used to test beta cell function in T1D patients receiving insulin injections

Answer 6

C peptide

Question 7

___ drugs promote the closing of ATP-dependent K+ channels and leads to increased insulin secretion. It can be used in the treatment of type 2 diabetes

Answer 7

Sulfonylurea, i.e., tolbutamide and glyburide

Question 8

Glucose stimulates insulin secretion in a ____ manner

Answer 8

Biphasic

See slide 11 for graph

Question 9

Insulin facilitates glucose uptake in some tissues by inserting this transporter ___ and insulin is required for glucose uptake in ___ tissues

Answer 9

GLUT 4

Adipose, resting skeletal muscle, and liver

Question 10

What are the major effects of insulin in skeletal muscle?

Answer 10

• Increase glucose uptake –> increases GLUT4 transporter
• Increase glycogen synthesis –> increase hexokinase (glucokinase in liver) and activate glycogen synthase
• Increase glycolysis and Carb oxidation –> increase hexokinase, PFKase, and pyruvate DHase
• Decrease gluconeogenesis
• Increase protein synthesis and decreas protein breakdown

Question 11

What effect does insulin have on triglyceride uptake in adipose tissue?

Answer 11

Insulin has a stimulatory effect on the uptake of TGs via lipoprotein lipase

Question 12

What effect does insulin have on the uptake of FA’s in adipose tissue?

Answer 12

Stimulatory effect

Question 13

WHat role does insulin play in the conversion of TG’s to glycerol via hormone sensitive lipase?

Answer 13

Inhibits hormone sensitive lipase

Question 14

WHat effect does insulin have in the uptake of glucose and conversion to a-Glycerol-P in adipose tissue?

Answer 14

Stimulatory effect

Question 15

What effect does insulin have on blood levels of the following:
A-Glucose
B-FA's
c-Ketoacids
D-AA's

Answer 15

All decreased

Question 16

What effect does insulin have on the following in the liver?
A-Glucokinase
B-Glycogen synthesis
C-Glucose-6-phosphatase (glucose release/gluconeogenesis)
D-Glycolysis
E-Triglyceride storage and export
F-Protein synthesis

Answer 16

a-Increase
B-Increase
C-Decrease
D-Increase
E-Increase
F-Increase protein synthesis, decrease protein degradation

Question 17

What effect does insulin have on the following in adipose tissue?
A-GLUT4 transporters
B-Glycolysis
c-Triglycerides (specifically hormone sensitive lipase and lipoprotein lipase)

Answer 17

A-Increase
B-Increase –> increase alpha-glyercol-phosphate, increase acetyl coa, increase FA synthesis
C-Increase –> decrease HSL, increase LPL

Question 18

What effect does insulin have on the following in skeletal muscle?
A-GLUT4 transporters
B-Glycogen synthesis
C-Glycolysis
D-Protein synthesis and degradation
e-Triglycerides

Answer 18

A-Increase
B-increase
C-increase
D-Increase synthesis, decrease degradation
E-Increase (FA's from circulation)

Question 19

What are some inhibitory factors of insulin?

Answer 19

Decrease blood glucose
Fasting
Exercise
Somatostatin
Alpha-adrenergic agonists
Diazoxide

Question 20

___ is characterized by inadequate insulin secretion, destruction of beta cells, often as the result of autoimmune disease

Answer 20

Type I DM

Question 21

Describe the levels of the following in Type I DM:
A-Blood [glucose]
B-Blood [FA] and [ketoacid]
C-[AA]

Answer 21

A-Increase –> decrease glucose uptake, decreased glucose utilization, increased gluconeogenesis

B-Increase –> decreased FA synthesis, decrease TG synthesis, Increased TG breakdown, increased level of circulating Free FA, increase conversion of FA to ketoacids and decreased ketoacid utilization by tissues (results in DKA: metabolic acidosis)

C-Increase –> increase protein breakdown, decreased protein synthesis, increased catabolism of AA (loss of lean body mass), increased ureagenesis

Question 22

What happens to K+ due to the effects on insulin in type 1 DM??

Answer 22

Hyperkalemia –> shift K+ out of the cell: IC [K+] is low, lack of insulin effect on Na/K ATPase

Even though plasma levels may be above normal, total body K+ is usually below normal due to the polyuria and dehydration

Question 23

What happens to GLUT4 uptake of glucose in response to insulin release in Type 2 DM?

Answer 23

Decreased

Question 24

What happens to HSL and LPL in adipose tissue in Type 2 DM?

Answer 24

Inability of insulin to repress HSL or increase LPL in adipose tissue

Question 25

What are some insulin secretagogue treatment options for type 2 DM?

Answer 25

Sulonylurea drugs and Incretin analog of GLP-1 (exenatide); injection needed

Question 26

What are some treatment options for the slow absorption of carbohydrates in pts with Type 2 DM?

Answer 26

Alpha-glucosidase inhibitors (acarbose, miglitol) Amylin analogs (pramlintide)

Question 27

What are some insulin sensitizers to treat type 2 DM?

Answer 27

Biguanide drugs (metformin): upregulate insulin receptors on target tissues

Question 28

To obtain [glucose] in mg/dL, multiply the value in mmol/L by ___

Answer 28

18

Question 29

Glucagon is a member of a family of peptides that includes the GI hormones ____

Answer 29

Secretin and GIP

Question 30

What are some stimulatory factors of glucagon secretion?

Answer 30

- decreased blood glucose - increased AAs (arginine and alanine) - Fasting - CCK - B-adrenergic agonists - Ach

Question 31

What are inhibitory factors of glucagon?

Answer 31

- Insulin secretion - Somatostatin - Increase [FA] and [ketoacid]

Question 32

What effect does glucagon have on glycogenolysis?

Answer 32

Increases --> inhibits glycogen formation from glucose

Question 33

What effect does glucagon have on gluconeogenesis?

Answer 33

Increases gluconeogenesis by decreasing the production of fructose 2,6-bisphosphate

Question 34

What effect does blood glucagon levels have on the following? A-blood Glucose b-FAs C-Ketoacids

Answer 34

All increase

Question 35

List examples of Incretin hormones

Answer 35

Intestine-derived hormones --> GLP-1, GIP Have a short 1/2 life and secreted in response to GI glucose and fat

Question 36

What effect does incretin hormones have on insulin secretion? Glucagon secretion? Gastric emptying?

Answer 36

Simulates insulin secretion Inhibits glucagon secretion Slow gastric emptying

Question 37

___ is ~60-65% of the islet of langerhans, secretes insulin and C peptide, and tends to be located in the peripheral core ___ is ~20% of the islet, secretes glucagon, and tends to be peripherally located ___ is ~5% of the islet and secretes somatostatin. Also have a neuronal appearance and send dendrite-like processes to cells that secrete insulin

Answer 37

Beta cells Alpha cells Delta cells--> interspersed between alpha and beta cells