26 Endocrine pancreas Flashcards
State all cell types in the pancreas and the hormones they secrete respectively.
- beta cells: insulin
- alpha cells: glucagon
- delta cells: somatostatin
- F/PP cells: pancreatic polypeptide
Briefly describe how different cell types are distributed in the pancreatic islet of the pancreas.
Alpha cells and delta cells: more on the periphery;
beta cells: within the center
Which of the following is false about the pancreas?
A. acetylcholine is the NT that affects glucagon and insulin secretion
B. Pancreas is only under autonomic control
C. effect of catecholamines on pancreatic hormone is to inhibit insulin and stimulate glucagon
B only
- Pancreas is innervated by autonomic nerve = autonomic control
- Pancreas is also under sympathetic control: epinephrine + hormonal control
C is true!
Describe the direction of blood flow in the pancreas islets. What is its significance?
From the core to the periphery, such that insulin can inhibit secretion of glucagon and maybe also somatostatin
Which of the following is false?
A. When high insulin is detected but there is normal level of C peptide, it indicates overdose of exogenous insulin
B. All proinsulin will have complete cleavage to insulin
C. in the regulated pathway, some maturing secretory granules will form lysosome
D. constitutive pathway may be caused by insulinoma
B
2 pathways in generating insulin:
1. Regulated pathway
○ Complete cleavage of proinsulin to insulin
○ 95% of beta cell insulin secretion
2. Constitutive pathway
○ Insulinoma
○ Releasing large amounts of unprocessed proinsulin
○ 5%
○ Discharge of proinsulin/insulin into circulation without signals
Lead to high insulin and proinsulin levels
List 2 stimulators, 2 amplifiers and 2 inhibitors of insulin secretion.
Stimulators:
- high blood glucose levels
- amino acids
- parasympathetic stimulation via acetylcholine
- free fatty acids and ketones
Amplifiers:
Incretins (GI hormones)
1. GIP
2. GLP-1 (glucagon-like peptide 1)
Inhibitors:
- somatostatin
- hypoglycemia
- catecholamines from sympathetic nerve innervation and secreted by adrenal medulla
Which of the following is true?
A. Glucose-induced insulin secretion is by insulin binding to GLUT4 transporter to activate glucokinase and G6P…
B. Sulphonylurea drugs are used for treating diabetic patients
C. Sulphonylurea drugs works by binding to SUR-1 receptors, which is made up of ATP-sensitive K+ channels, causing it to open
D. Incretin amplifies glucose-induced insulin release by genomic action
B only
A: should be GLUT2 transporters
C: should be causing it to close
D. should be by second messenger system: through PKA > cAMP > Ca2+
Biphasic release of insulin appears to originate from a readily releasable and reserve pool of insulin.
What happens to patients with Type 2 DM?
Loss of first-phase of insulin secretion due to the deterioration of beta-cell function with depleted store of insulin, loss of sensitivity and responsiveness to glucose
Why is an OGTT but not IV injection of glucose more suitable to test for insulin function?
Oral dose can stimulate a greater rise in insulin secretion that IV > can test for maximum insulin secretory response.
Presence of incretin in gut has amplifying effect on insulin
Post-translational processing of preproglucagon generates __________ in intestinal L cells and glucagon in pancreatic A cells.
GIP-1 (Glucagon-like peptide)
Which of the following is true about the actions of GIP-1?
A. It promote satiety B. It slows gastric emptying C. It inhibits glucagon secretion D. It restores beta cell function E. it promotes beta cell differentiation
all of the above
What drug class does exenatide and liraglutide belongs to?
They belong to GIP-1 receptor agonists.
Which of the following is false about GIP-1 receptor agonists?
A. They are used because GIP-1 has short biological half life due to the degradation of DPP-4
B. They have longer biological half lives due to their binding to albumin
C. Most of them are taken orally.
D. Lixisenatide is one of the examples
E. They pose hypoglycemic risk
C
most of them are given by subcutaneous injection
DPP-4 inhibitors can also be used, taken orally
E as well
no hypoglycemic risk
How can we treat DM2 patients in the renal perspective?
Give inhibitors of SGLT 2 (sodium-glucose transporters) to increase glucose excretion, no risk of hypoglycemia
Which of the followings about insulin effects is/are false?
A. it promotes the release of K+ ions from cells
B. It promotes protein synthesis
C. It promotes glycolysis
D. It inhibits ketogenesis
E. It inhibits glycogenolysis
A
Should be promote the uptake of K+ ions
