DSA: Pancreatic fn. and Carbohydrate Metabolism

Question 1

alpha cells

Answer 1

produce glucagon

Question 2

Beta cells

Answer 2

produce insulin - greatest number of endocrine cells

Question 3

Gamma cells

Answer 3

produce somatostatin

Question 4

F cells

Answer 4

Produce pancreatic polypeptide

Question 5

fasting state

Answer 5

Beta cell secretes less insulin. when insulin levels decrease, lipids are mobilized from adipose tissue, ad AA’s are mobilized from body protein stores within muscle and other tissue.

Question 6

feeding state

Answer 6

insulin secretion increases
- elevated levels of insulin diminish the mobilization of endogenous fuel stores and stimulate car. lipid and AA uptake, insulin directs tissues to replenish the fuel reserves

Question 7

what triggers insulin secretion?

Answer 7

• metabolism of glucose, galactose and mannose provoke insulin secretion.
• Arginine, leucine, keto acids and fructose also stimulate insulin secretion
• glucagon has been a strong insulin secretion

Question 8

how does glucose trigger insulin release?

Answer 8

1. glucose enters the B cell through GLUT2 glucose transporter by facilitated diffusion.
2. In the presence of glucokinase, the entering glucose undergoes glycolysis and raises inctracellular ATP concentration.
3. The increased [ATP] or elevated [NADH] cause K-ATP channels to close.
4. Reducing the K+ conductance of the cell membrane causes the Beta cell to depolarize
5. The depolarization activates voltage gated Ca2+ channels
6. The increased Ca2+ permeability leads to increased Ca2+ influx and intracellular [Ca2+] increases resulting in Ca2+-induced-Ca2+ release.
7. The increased intracellular [Ca2+] leads to insulin release

Question 9

Insulin and exercise

Answer 9

• Sympathetic stimulation during exercise results in alph-adrenergic inhibition of insulin secretion during exercise to prevent hypoglycemia

Question 10

3 intecrins promoting insulin secretion

Answer 10

CCK, GLP-1, GIP - all are released by gut tissues in response to feeding.

Question 11

insulin effect on liver….

Answer 11

• insulin causes glucose uptake by liver via GLUT2 receptor and results in glucogenolysis via stimulating glucokinase and glycogen synthase, while downregulating glycogen phosphorylase activity- results in glycogen being stored in both the liver and in the muscle.
• insulin also promotes the storage of fats and inhibits oxidation of fatty acids through allosteric modification of key regulatory enzymes
• insulin stimultaes the synth. of proteins and reduces the degredation of protein within the liver

Question 12

insulin effect on muscle:

Answer 12

• promotes uptake of glucose via the GLUT4 receptor and enhances conversion of glucose to glycogen, and the formation of protein in skeletal muscle
• both exercise and insulin result in increased recruitment of GLUT4 transporters

Question 13

Insulin effect in adipocytes

Answer 13

• results in uptake of glucose and conversion to triglycerides for storage via GLUT4 transporters

Question 14

Glucagon

Answer 14

• principally targets the liver, secreted first into the portal blood
• stimulates glycogenolysis, gluconeogenesis and ketogenesis
• promotes oxidation of fat in liver, which can lead to formation of ketone bodies

Question 15

DM Type I

Answer 15

• immune-mediated selective destruction of the beta cells of the pancreas
• results in loss of insulin
• glucose and ketone production occur at a high rate, the keto acids lower the pH resulting in diabetic ketoacidosis.
• will respond well to insulin treatment

Question 16

DM Type II

Answer 16

• continue to make insulin however Beta cells do not respond normally to increase in plasma glucose by increasing insulin secretion.
• furthermore doses of insulin to liver, muscle and adipose tissue have limited action
• both metabolism of glucose in response to insulin and the secretion of insulin are abnormal
• usually severe ketoacid doesn’t develop b/c these individuals produce enough insulin