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COM - Endocrine > Endocrine Pancreas - 2/5 Lopez > Flashcards

Endocrine Pancreas - 2/5 Lopez Flashcards

1
Q

What are the major functions of the endocrine pancreas?

A

Regulate glucose, fatty acid, and a.a. Metabolism

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2
Q

What do beta cells secrete?

How much of the islet?

Located where?

A

Insulin and C peptide

60-65%

Central core

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3
Q

What do alpha cells secrete?

What %

Located where?

A

Glucagon

20%

Periphery of islet

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4
Q

What do delta cells secrete?

What %

Located where?

A

Somatostatin

5%

Interspersed between alpha and beta cells

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5
Q

How does blood flow in the islet cells?

A

Blood flows 1st to capillaries in the center of the isle to pick up insulin, then flows to periphery, where it acts on alpha cells to inhibit glucagon secretion

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6
Q

What does somatostatin release inhibit?

A

Glucagon and insulin

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7
Q

What links beta cells together and alpha cells together for communication within the endocrine pancreas?

A

Gap junctions

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8
Q

Describe the structure of insulin

A

Made up of alpha and beta chain, linked by 2 disulfide bridges

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9
Q

Preproinsulin contains what 4 peptides?

A

Signal peptide, alpha and beta chains, C peptide

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10
Q

What happens to proinsulin to become active?

When is proinsulin cleaved?

A

DB for in the ER and packed into secretory vesicles in the Golgi

During packaging

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11
Q

What kind of drugs(and names) are used to treat DM type II?

How do they work?

A

Sulfonylurea drugs - tolbutamide and glyburide

Close ATP dependent K+ channels

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12
Q

How is insulin secreted?

A

Biphasic: initially burst of preformed insulin followed by sustained secretion of newly synthesized insulin

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13
Q

How does CCK and ACh affect insulin?

Via what mechanism?

A

Stimulates insulin release

Gq -> INC intracellular [Ca]

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14
Q

How does somatostatin affect insulin release?

Via what mechanism?

A

Inhibits it

Gi blocks cAMP

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15
Q

How does glucagon affect insulin release?

Via what mechanism?

A

Stimulates it

GLP-1 receptor -> Gq -> IP3/DAG -> [Ca] -> insulin release

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16
Q

What is the insulin receptor made of?

Which parts are located where?

What has intrinsic Tyr Kinase activity?

A

Tetramer of 2 alpha and 2 beta subunits

alpha extracellular, beta span the CM

Beta

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17
Q

What can insulin do to its receptor?

# of insulin receptors in starvation?
Obesity?
A

Down-regulate them

INC
DEC

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18
Q

What are the metabolic effects of insulin?

A 
GLUT4 and GLUT12 translocation to CM
Activation of phosphatases
Activation of mTORC1
Activation of SREBP1c
Inhibition of FOXO1 activity
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19
Q

Peripheral uptake of glucose occurs via what mechanism?

What transporter?

What tissues use this method?

A

FD from peripheral cells

GLUT4

Adipose tissue, resting skeletal m.

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20
Q

How does glucose enter skeletal muscle cells?

A

GLUT4 transporter

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21
Q

What enzyme in the muscle converts glucose to G1P?

How does glycogen synthesis occur afterwards? (Name substrate, product enzyme)

A

Hexokinase

G1P -> glycogen via glycogen synthase

22
Q

How does insulin affect the following in muscle cells?

Glycolysis
Gluconeogensis
Protein synthesis
Protein breakdown

A

INC
DEC
INC
DEC

23
Q

F6P -> F-1,6-BP with what enzyme?

A

PFK

24
Q

Pyruvate -> acetyl-CoA via what enzyme?

A

Pyruvate dehydrogenase

25
Q

What does insulin stimulate the uptake of in adipose cells?

A

Glucose, TAgs, F.A.’s

26
Q

In adipose tissue what are the main actions of insulin?

A

Inhibit lipolysis

Stimulate fat deposition (TAGs)

27
Q

Uptake of TGs is mediated by what enzyme?

A

Lipoprotein lipase (LPL)

28
Q

What enzyme does insulin inhibit?

A

hormone sensitive lipase (HSL)

29
Q

Insulin decreases what in the blood?

A

Glucose
Fatty acids
Ketoacidosis
Amino acids

30
Q

How does insulin affect the following?

Glucose uptake into cells
Glycogen formation
Glycogenolysis
Gluconeogensis
Protein synthesis 
Fat deposition
Lypolysis
K+ uptake into cells
A 
INC
INC
DEC
DEC
INC
INC
DEC
INC
31
Q

How do the following affect insulin?

Glucagon
Cortisol
Exercise
K+
Fasting
Obesity
Diazoxide
GIP
ACh/Vagal stimulation
A 
stimulate
Stimulate
Inhibit
Stimulate
Inhibit
Inhibit
Stimulate
Inhibit
Stimulate
Stimulate
32
Q

How do sulfonylurea drugs affect insulin?

Alpha-adernergic agonists?

A

Stimulate

Inhibit

33
Q

DM type I affects [a.a.] how?

Protein breakdown?
Protein synthesis?
Catabolism of a.a.?
Urea genesis?

A

DEC

INC
DEC
INC
INC

34
Q

How does INC blood [glucose] affect the filtered load of glucose?
What does this do?

What is prevented?

Ultimate result?

A

INC
Exceeds reabsorption capacity of PCT

Water and electrolyte reabsorption

Thirst, Polyuria and excretion of Na and K

35
Q

How does DM type I affect K, i.e. What does it cause?

Why?

A

hyperkalemia, less K+ uptake into cells

Lack of effect on Na/K ATPase

36
Q

What does DM type I cause in patients due to ECF volume contraction?

How does this happen?

A

Hypotension

Unabsorbed glucose acts as an osmotic diuretic in the urine

37
Q

What are 3 causes of obesity-induced insulin resistance?

A

Dec GLUT4 uptake of glucose
Dec ability of insulin to repress hepatic glucose production
Inability of insulin to repress HSL or INC LPL in adipose

38
Q

In non-obese patients, how else can DM type II occur?

A

DEC insulin release by the pancreas

39
Q

Injection of what GLP-1 analogue may treat DM type II?

A

Exenatide

40
Q

What drugs treat DM type II via slow absorption of carbohydrates?

A 
Alpha-glucosidase inhibitors (acarbose, miglitol)
Amylin analogs (pramlintide)
41
Q

What drugs are insulin sensitizers (tx for DM type II)?

A

Biguanide drugs ie metformin (upregulates receptors on target tissues)

42
Q

How is glucagon synthesized?

How is it stored?

A

Preproglucagon

Dense granules until alpha cells are stimulated

43
Q

What is the major stimulatory factor of glucagon?

What else stimulates it?

A

DEC blood [glucose]

INC a.a.

44
Q

What accessory stimulatory factors activate glucagon?

A

fasting
CCK
ACh
Beta-adrenergic agonists

45
Q

What else will inhibit glucagon secretion?

A

Somatostatin
INC F.A.
INC ketoacid

46
Q

What tissue does glucagon act on?

What 2nd messenger does it use?

A

Liver, adipose

cAMP

47
Q

How does glucagon secretion affect glycogenolysis?

Gluconeogenesis?

A

INC

INC

48
Q

What enzyme does glucagon decrease the production of?

What does this do?

A

F-2,6,BP thus decreasing PFK

Favors glucose formation

49
Q

What effects does glucagon have in adipose tissue?

A

INC lipolysis

Inhibits F.A. Synthesis

50
Q

What are the intestine derived hormones?

Secreted in response to what?

What effect?

A

GLP-1, GIP

GI glucose and fat

Stimulate insulin secretion, inhibit glucagon, and slow gastric emptying

51
Q

What do endocrine cells secrete?

A

Insulin, glucagon, somatostatin

COM - Endocrine (12 decks)

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