Endocrine Pancreas

Question 1

Insulin receptors are inc in ….& dec in….

Answer 1

Starvation
Obesity

Question 2

GLUT4 move in cell membrane independent of insulin in response to……

Answer 2

Exercise

Question 3

The major insulin independent organs are……

Answer 3

Brain, liver, RBCs, epithelial cells of kidney & intestine

Question 4

Describe effects of insulin on CHO metabolism

Answer 4

1. Facilitation of glucose transport into the cells of insulin-senisitive tissues
2. Stimulation of glycogenesis by activating glycogen synthase
3. Inhibition of gluconeogenesis & glycogenolysis (by inhibiting glycogen phosphorylase

Question 5

How does insulin inc liver glucose uptake?

Answer 5

Induces glucokinase which induces phorphorylation of glucose so free glucose remains low facilitating glucose entry into cells.

Question 6

Describe effects of insulin on fat metabolism

Answer 6

1. Lowers blood fatty acids
2. Promotes triglyceride storage (by inc glucose transport to adipose tissue forming a-glycerol phosphate, inc transport of FFA from blood to adipose tissue by activating lipoprotein lipase)
3. Inhibits lipolysis by inhibiting intracellular HSL

Question 7

Describe effects of insulin on protein metabolism

Answer 7

1. Lowers blood amino acids level
2. Inc protein synthesis (inc AA uptake & incorporation in proteins by stimulating cell’s protein-synthesizing machinery
3. Inhibits protein catabolism
   THUS, essential for normal growth

Question 8

With respect electrolytes, insulin causes…….

Answer 8

K+ entry to cells

Question 9

Describe principal actions of insulin on muscle

Answer 9

1. Inc glucose entry & glycogenesis, dec glycogenolysis
2. Inc AA uptake & protein synthesis, dec degradation
3. Inc K+ entry to cells

Question 10

Describe principal actions of insulin on liver

Answer 10

1. Inc glucose entry & glycogenesis, dec glycogenolysis & gluconeogenesis
2. Inc AA uptake & protein synthesis, dec degradation
3. Inc K+ entry to cells
4. Inc lipid synthesis, dec ketogenesis

Question 11

Describe principal actions of insulin on adipose tissue

Answer 11

Inc glucose entry
Inc synthesis of glycerol phosphate, triglycerides & fatty acids.
Activate LPL, inhibit HSL
Inc K+ entry to cells

Question 12

The primary control of insulin secretion is……

Answer 12

Direct -ve feedback system between B-cells & conc of blood glucose

Question 13

Metabolism of pyruvate via TCA causes inc……, explain its effects on insulin

Answer 13

Glutamate, appears to act on 2nd pool of secretory granules committing them to the releasable form, it may act by dec pH which is a necessary step in secretory granules maturation, thus it is responsible for prolonged phase of insulin response to glucose (2nd messenger).

Question 14

AAs that stupimulate insulin

Answer 14

Arginine & lysine
L-arginine also by NO

Question 15

Mention the “incretins” & their role
They ar degraded by….

Answer 15

GIP, GLP-1
They enhance the rate of insulin release from pancreatic B cells to inc plasma glucose level, they cause anticipatory inc in blood insulin in preparation for glucose & AAs to be absorbed from the meal.
DPP-4

Question 16

Describe effect of ANS on insulin secretion

Answer 16

Parasympathetic stimulatory to insulin by M4
Sympathetic inhibitiry by a2 (b2 is present & stimulatory but its effect is weaker than a2, thus net effect is inhibition)

Question 17

Describe effects of other hormones on insulin

Answer 17

1. Glucagon inc it by inc cAMP in B cells & also by caused by hyperglycemia
2. Somatostatin is inhibitory
3. Cortisol, GH, estrogen & progesterone diretly either inc insulin secretion or potentiate its glucose stimulus.

Question 18

Describe effects on insulin of each:
1. Leptin
2. cAMP

Answer 18

1. Dec food intake & inhibit insulin release
2. Inc insulin secretion, caused by b-agonists, glucagon, theophyline

Question 19

Describe phases of hypoglycemia & its treatment

Answer 19

1. Sympathetic overactivity (less than 70mg%): tremors, nervousness, tachycardia, palpitations, sweating, dilated pupil, in BP
2. CNS symptoms (less than 40mg%): due to neuroglycopenia: confusion, weakness, dizziness & convulsions
3. Brainstem phase (less than 20mg%): coma
   TTT: IV/oral glucose + IV glucagon

Question 20

Mention metabolic functions of glucagon

Answer 20

1. Hyperglycemia by glycogenolysis & gluconeogenesis
2. Lipolytic, inc FFA & glycerol release & inc ketoacid formation
3. Inc ureagenesis due to inc gluconeogenesis
4. Other: enhance myocardial contractility, facilitates secretion of GH, inuslin & pancreatic somatostatin

Question 21

Describe control of glucagon secretion

Answer 21

1. Dec in blood glucose inc secretion & vice versa
2. AA inc stimulates it esp alanine & arginie
3. Hormones:
   Somatostatin, secretin, insulin: inhibit
   CCK, gastrin: stimulate
4. Vagal stimulate, sympathetic stimulate (a2 & b2 are present but b2 are predominant)
5. Exercise: can inc 4 or 5-fold by b-adrenergic stimulation
6. Infections, toxemia, burns, surgery are stimulatory (symoathetic activity)

Question 22

I/G molar ratio is…..in balanced diet, …..in 3 days of starvation, ……in continuous glucose infusion.

Answer 22

2.3
0.4
25

Question 23

Describe actions & mentions stimulants of pancreatic somatostatins

Answer 23

1. Inhibit insulin & glucagon secretion
2. Dec GIT secretion & delays gastric emptying
   Stimulated by high blood glucose & AAs, glucagon, CCK.

Question 24

Describe effects of the following on glucose homeostasis:
1. CAs
2. Glucocorticoids

Answer 24

1. Inhibit insulin & inc glucagon, stimulate glycogenolysis & gluconeogenesis
2. Stimulate gluconeogenesis & cause insulin resistance

Question 25

Describe effects of the following on glucose homeostasis:
1. GH
2. Thyroid hormones

Answer 25

1. Dec glucose uptake in tissue as skeletal muscle & fat (insulin resistance)
2. Inc glucose absorption, glycogenolysis (potentiate CAs), gluconeogenesis.