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PHYSIOLOGY MED1 > Endocrine Pancreas > Flashcards

Endocrine Pancreas Flashcards

1
Q

Which of the 2 major types of tissue in the pancreas secrete digestive juices to the duodenum?

A

Acini

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2
Q

The hormone that is often secreted by beta cells of the pancreas in parallel with insulin

A

Amylin - inhibits insulin secretion

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3
Q

Which of the following is NOT true of insulin?
A. It causes storage of excess carbohydrates as glycogen
B. It converts excess carbohydrates into fats
C. It has a direct effect in promoting amino acid uptake in cells
D. It promotes the breakdown of proteins in cells

A

D since it should be: it inhibits the breakdown of proteins that are already in the cells.

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4
Q 
Which of the following is not secreted by pancreatic beta cells?
A. Proinsulin
B. C peptide
C. Pancreatic Polypeptide
D. Amylin
A

C. Pancreatic Polypeptide

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5
Q

Hormone secreted by some pancreatic islet cells that is the counterpart of the hypothalamic growth hormone-inhibiting hormone?

A

Somatostatin

  • in the pancreas, it’s an inhibitor of insulin
  • in the GIT, it’s an inhibitor of gastrin and secretin secretion; reducing gastric secretions and motlity
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6
Q

Which hormone secreted by F cells in the pancreas plays a role in appetite?

A

Pancreatic polypeptide

  • after a meal: it reduces further food consumption
  • also released during fasting
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7
Q 
First cells affected by circulating insulin:
A. Beta cells
B. Alpha cells
C. Delta cells
D. PP cells
A

B. Alpha cells

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8
Q 
All of the following are inhibited by somatostatin except:
A. Insulin
B. Glucagon
C. Growth hormone
D. Cortisol
A

D. Cortisol

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9
Q 
Which of the following would result to insulin secretion?
A. Cholinergic stimulation
B. Beta-adrenergic stimulation
C. Alpha-adrenergic stimulation
D. Both A and B
E. Both A and C
A

D. Both Cholinergic and Beta-adrenergic stimulation

C inhibits insulin secretion

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10
Q 
Which of the following is NOT included in the same gene family of insulin?
A. IGF I
B. IGF II
C. Relaxin
D. NOTA
A

D. NOTA

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11
Q 
Which of the following contents of pre-proinsulin is cleaved to produce proinsulin?
A. Leader sequence
B. C peptide
C. A chain
D. B chain
E. NOTA
A

A. Leader sequence (or the N-terminal signal peptide according to Berne)

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12
Q

Which enzymes are packaged with proinsulin in its secretory granule?

A

protein convertases 1/3 and 2

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13
Q

Which of the following is the correct sequence of the synthesis of insulin?
A. N-terminal signal peptide > A chain > B chain > C chain
B. N-terminal signal peptide > B chain > C chain > A chain
C. C chain > B chain > A chain > N-terminal signal peptide
D. C chain > A chain > B chain > N-terminal signal peptide

A

B. N-terminal signal peptide > B chain > C chain > A chain

Insulin is a protein hormone that belongs to the gene family that includes insulin-like growth factors I and II (IGF-I, IGF-II), relaxin, and several insulin-like peptides. The insulin gene encodes preproinsulin. Insulin is synthesized on the polyribosome as preproinsulin, and microsomal enzymes cleave the N-terminal signal peptide to produce proinsulin as the peptide enters the endoplasmic reticulum. Proinsulin is packaged in the Golgi apparatus into membrane-bound secretory granules. Proinsulin contains the AA sequence of insulin plus the 31-amino acid C (connecting) peptide and four linking AAs. The proteases that cleave proinsulin (proprotein convertases 1/3 and 2) are packaged with proinsulin within the secretory granule. The mature hormone consists of two chains, an α chain and a β chain, connected by two disulfide bridges. A third disulfide bridge is contained within the α chain. Insulin is stored in secretory granules in zinc-bound crystals. On stimulation, the granule’s contents are released to the outside of the cell by exocytosis.

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14
Q

The enzyme responsible for the degradation and rapid half-life of insulin

A

insulinase

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15
Q

Which of the following is true of insulin?
A. Insulin has a half-life of 15-20 min
B. Almost half of insulin is degraded before leaving the liver
C. When needed by the body, the proinsulin is cleaved at 3 sites, releasing the C peptide
D. Active insulin composed of A chain and B chain have itsbiological activity in the A chain
E. AOTA

A

B. Almost half of insulin is degraded before leaving the liver

A should be 5-8 min
C should be 2 sites
D should be ‘B chain’ for biological activity

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16
Q 
Active insulin has a very short half-life, which of the following gives more or less an index of the beta cell action?
A. A chain
B. B chain
C. C chain
D. D chain
E. AOTA
A

C. C chain

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17
Q 
Which of the following substrates stimulates insulin secretion?
A. Glucose
B. Ketoacids
C. Proteins
D. Fats
E. AOTA
A

E. AOTA

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18
Q

Which ions stimulate the release of insulin?

A

K and Ca

19
Q

All are inhibitors of insulin secretion except:
A. Leptin
B. Incretins
C. Somatostatin
D. Epinephrine via alpha-adrenergic stimulation
E. Fasting

A

B. Incretins

20
Q 
Which of the following hormones enhances rate of insulin release from pancreatic beta cells in response to elevated blood glucose?
A. GIP
B. GLP-1
C. Incretin
D. AOTA
A

D. AOTA

21
Q

All are true of the stages of insulin secretion except:
A. The late phase is due to activation of enzymes systems that synthesize and release new insulin from cells
B. The acute elevation in early phase results from dumping of preformed insulin from beta cells
C. The late phase reaches a plateau in 2-3 hours
D. The rate of secretion in greater in the early phase

A

D. The rate of secretion in greater in the early phase IS WRONG since Rate of secretion in Late > Early

21
Q

All are true of the stages of insulin secretion except:
A. The late phase is due to activation of enzymes systems that synthesize and release new insulin from cells
B. The acute elevation in early phase results from dumping of preformed insulin from beta cells
C. The late phase reaches a plateau in 2-3 hours
D. The rate of secretion in greater in the early phase

A

D. The rate of secretion in greater in the early phase IS WRONG since Rate of secretion in Late > Early

22
Q

The rate limiting step that mediates glucose control on insulin release is the:
A. Β-cell glucose transporter 2 (GLUT-2)
B. Calcium-mediated fusion of the granules with the plasma membrane
C. ATP sensitive K+ channel
D. Β-cell glucokinase

A

D. Β-cell glucokinase
Glucose is phosphorylated to G6P by glucokinase
▪ Rate-Limiting step in Glucose metabolism
▪ Major Mechanism for glucose sensing

23
Q 
Which of the following is the mechanism of action of sulfonylurea-based oral hypoglycemics in beta cells?
A. ATP-sensitive K+ channels
B. GLUT2
C. Voltage-gated Ca+ channels
D. GLP1R
A

A. ATP-sensitive K+ channels
In the normal response to glucose, increased ATP inhibits ATP sensitive K+ channels thus closing it leading to depolarization
→ Depolarization opens voltage gated Ca++ channels which will increase cytoplasmic Ca++, stimulating fusion of docked insulin-containing vesicles with cell membranes
→ Insulin is secreted via exocytosis
This mechanism is mimicked by sulfonylureas as it closes the same K+ channels

24
Q 
Which of the following molecules stimulate the release of insulin via the PLC/IP3 pathway?
A. ACh
B. CCK 
C. GLP-I
D. Both A and B
E. AOTA
A

D. both A and B

25
Q 
Which of the following are stimulators of insulin secretion?
A. Secretin
B. Galanin
C. PGE2
D. Pancreastatin
E. IL-1
A

A. Secretin

Galanin, PGE2, Pancreastatin, IL-1 are all inhibitors of Insulin secretion

26
Q 
Which of the following are inhibitors of insulin secretion?
A. Meglitinides
B. Beta-adrenergic activity
C. Diazoxide
D. Sulfonylurea drugs
E. NOTA
A

C. Diazoxide

Meglitinides, Beta-adrenergic activity, Sulfonylurea drugs are all stimulators of insulin secretion

27
Q 
Which of the following does not stimulate CPIR?
A. Starch
B. Sour
C. Bitter
D. Umami
E. AOTA
A

E. AOTA

28
Q

Type of receptor for insulin

A

Receptor Tyrosine kinase

29
Q 
Which of the following is activated to promote protein synthesis and inhibits proteosomal-mediated protein degradation in insulin target cells?
A. GLUT4
B. mTORC1
C. SREBP1
D. FOXO1
A

B. mTORC1 (mechanistic target of rapamycin complex 1)

30
Q 
Which of the following induces the enzyme that catalyzes the first reaction in PPP?
A. GLUT4
B. mTORC1
C. SREBP1
D. FOXO1
A

C. SREBP1 (sterol response element binding protein 1)

31
Q 
Which of the following orchestrates glycolysis and de novo lipogenesis for production of phospholipids, fatty acids, and triglycerides from excess glucose and fructose?
A. GLUT4
B. mTORC1
C. SREBP1
D. FOXO1
A

C. SREBP1 (sterol response element binding protein 1)

32
Q 
Which of the following cells utilizes GLUT2 as glucose transporters?
A. Muscle
B. Adipose tissue
C. B-cells
D. NOTA
A

C. B-cells

as well as Liver and Kidney

33
Q 
Pyruvate dehydrogenase promotes which of the following effects as facilitated by insulin on the liver?
A. Oxidation of Pyruvate
B. Reduction of Pyruvate
C. Hydrolysis of Pyruvate
D. Phosphorylation of Pyruvate
A

A. Oxidation of Pyruvate

34
Q

Insulin is considered an antiketogenic hormone because:
A. Ketoacids are used as energy in the brain
B. Insulin increases malonyl Co-A which inhibits carnitine acyltransferase
C. Insulin inhibits the use of ketoacids by the peripheral tissues
D. Free fatty acids in the circulation is directed toward β-oxidation

A

B. Insulin increases malonyl-CoA which inhibits carnitine acyltransferase
- prevents fatty acids from entering the mitochondria for oxidation

35
Q

How does insulin promote lipogenesis in adipocytes?

A

Conversion of pyruvate by pyruvate dehydrogenase to acetyl-CoA, which is then converted to malonyl-CoA via acetyl carboxylase

36
Q

Which of the following is a normal response of adipocytes in fat metabolism?
A. inhibition of hormone-sensitive lipase to prevent lipolysis
B. promotion of synthesis of lipoprotein lipase
C. promotion of esterification of glycerol phosphate with fatty acids to form TAG
D. conversion of pyruvate to fatty acids
E. AOTA

A

E. AOTA

37
Q

Which of the following is an effect of insulin on muscles?
A. Promotes glucose uptake and release
B. Enhances transcription of glucokinase
C. Activation of glycogen synthase
D. Promotes glycolysis and carbs oxidation by increasing the activity of glucokinase, hexokinase, PFK, and PDH

A

C. Activation of glycogen synthase to promote glycogen synthesis

A should be uptake only (via recruitment of GLUT4)
B and D should be hexokinase

38
Q

Which of the following is/are true of glucagon?
A. Decreases intramitochondial fatty acid oxidation
B. Enhances ketogenesis in hepatocytes and muscles
C. Primary catabolic counterregulatory hormone that increases blood glucose levels
D. Predominantly degraded in the pancreas
E. AOTA

A

C. Primary catabolic counterregulatory hormone that increases blood glucose levels

A should be ‘enhances’
B should only be in hepatocytes
D glucagon is predominantly degraded in the liver

39
Q 
The following hormones are members of the secretin gene family, having the AA sequence of the precursor preproglucagon, except:
A. Glucagon
B. GLP-1
C. GLP-2
D. GLP-3
E. NOTA
A

D. GlP-3

no such thing

40
Q

Which of the following is true of Proglucagon?
A. Also expressed in Pancreatic beta cells
B. Expressed in Enteroendocrine L-cells and in neurons of Brainstem and Hypothalamus
C. Processed by prohormone convertase 1/3 to glucagon in pancreas
D. Processed by prohormone convertase 2 to glucagon in intestine and brain
E. AOTA

A

B. Expressed in Enteroendocrine L-cells and in neurons of Brainstem and Hypothalamus

A should be Pancreatic beta cells and others (B)
C PC2 (greater activity in alpha cells) processes proglucagon to glucagon as well as the major fragments, GRPP and MPGF (GLP-1 and 2) in the PANCREAS
D PC1/3 process proglucagon in the INTESTINE (grater activity in the L-cells) and the BRAIN leading to the formation of GLP-1 and GLP-2 and the major fragments glicentin and oxyntomodulin

41
Q

Normal plasma glucagon concentration range:

A

50-100 pg/mL

42
Q

The major stimulus of glucagon release

A

Hypoglycemia

43
Q

Which of the following is an inhibitory regulator of glucagon release?
A. Gastric inhibitory peptide
B. Glucagon-like Peptide 1

A

B. Glucagon-like Peptide 1

PHYSIOLOGY MED1 (15 decks)

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