INSULIN – RECEPTORS AND REGULATION OF SECRETION
Which is/are the GI hormones stimulating insulin secretion?
| A |
GIP |
|
| B |
Gastrin |
|
| C |
Secretin |
|
| D |
All of the above |
Which is/are the GI hormones stimulating insulin secretion?
| A |
GIP |
|
| B |
Gastrin |
|
| C |
Secretin |
|
| D |
All of the above |
GIP, Gastrin, Secretin & CCK.
Stimulating factor for insulin secretion:
- Glucose – Relationship between glucose concentration & insulin secretion is “SIGMOIDAL“
- Mannose
- Amino acids (arginine, leucine)
- Intestinal hormones –GLP -1.
- GIP.
- Gastrin.
- Secretin.
- CCK
- β-keto acids
- Parasympathetic stimulation –
- Acetylcholine
- cAMP
- β-adrenergic stimulation.
- Drugs:Endocrine hormones like Growth hormone, Glucagon & Glucocorticoids.
- Theophylline.
- Sulfonylureas
How many polypepide chains does insulin compose of ?
| A |
4 chains |
|
| B |
3 chains |
|
| C |
2 chains |
|
| D |
5 chains |
How many polypepide chains does insulin compose of ?
| A |
4 chains |
|
| B |
3 chains |
|
| C |
2 chains |
|
| D |
5 chains |
- Insulin is two-chain polypeptide hormone, with 51 amino acids.
- Structure:
- 2 chains – A & B chain.
- A – chain – 21 amino acids; B – chain – 30 amino acids.
- Half-life-: About 5 mins
Which drug inhibits insulin secretion?
| A |
Phenytoin |
|
| B |
amoxicillin |
|
| C |
Insulin itself |
|
| D |
Both A & C |
Which drug inhibits insulin secretion?
| A |
Phenytoin |
|
| B |
amoxicillin |
|
| C |
Insulin itself |
|
| D |
Both A & C |
Phenytoin & insulin itself.
Insulin secretion inhibiting factors:
- Somatostatin
- 2-deoxyglucose
- Mannoheptulose
- α-adrenergic stimulation
- β-adrenergic inhibitors
- Galanin
- Alloxan
- Electrolyte – K+ depletion
- Drugs:
- Diazoxide.
- Thiazide diuretics.
- Phenytoin.
- Microtubule inhibitors.
- Note: Insulin itself is an inhibitor.
Which is the singke most important factor that stimulates insulin secretion?
| A |
Decreased plasma glucose concentration inhibits insulin release. |
|
| B |
Decreased plasma glucose concentration stimulate insulin release. |
|
| C |
Increased plasma glucose concentration stimulate insulin release. |
|
| D |
Increased plasma glucose concentration inhibits insulin release. |
Which is the singke most important factor that stimulates insulin secretion?
| A |
Decreased plasma glucose concentration inhibits insulin release. |
|
| B |
Decreased plasma glucose concentration stimulate insulin release. |
|
| C |
Increased plasma glucose concentration stimulate insulin release. |
|
| D |
Increased plasma glucose concentration inhibits insulin release. |
Plasma glucose concentration:
- Increased plasma glucose concentration stimulate insulin release.
- Glucose entry is “Insulin-independent” via GLUT-2.
- Glucose metabolized to pyruvate.
- Ca2+ influx causes insulin efflux from secretory granules (secretion).
FACTORS INFLUENCING:
1. Stimulating factor:
- Glucose – Relationship between glucose concentration & insulin secretion is “SIGMOIDAL“
- Intestinal hormones –GLP -1.
- GIP.
- Gastrin.
- Secretin.
- CCK
- Parasympathetic stimulation – via acetylcholine.
- Endocrine hormones – Growth hormone, Glucagon & Glucocorticoids.
