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Step 1 > Endocrine Physiology > Flashcards

Endocrine Physiology Flashcards

1
Q

Pathway of insulin synthesis

A

Preproinsulin made in RER with cleavage of “presignal”: the proinsulin is stored in secretory granules

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2
Q

C-peptide is secreted in what ratio to insulin

A

Exocytosis of insulin and C-peptide equally

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3
Q

Insulin pathway

A

Binds tyrosine kinase receptor dimers inducing glucose uptake in insulin-dependent tissue and gene transcription.

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4
Q

Anabolic effects of insulin

A
  1. Increased glucose transport in skeletal muscle and adipose
  2. inc. glycogen synthesis and storage
  3. inc. triglyceride synthesis
  4. inc. Na+ retention (kidneys)
  5. Inc. protein synthesis (muscles, proteins)
  6. Inc. cellular uptake of K+ and amino acids
  7. Dec. glucagon release
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5
Q

Insulin crosses placenta how much

A

Never

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6
Q

Insulin-dependent glucose transporter

A

GLUT-4

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7
Q

Insulin-independent transporters

A

GLUT-1: RBCs, brain, cornea
GLUT-5: Fructose: spermatocytes, GI tract
GLUT-2: Bidirectional: Beta islet cells, liver, kidney, small intestine

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8
Q

Mnemonic for insulin-independent glucose uptake

A

BRICK L

Brain, RBCs, Intestine, Cornea, Kidney, Liver

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9
Q

How does Growth Hormone affect insulin levels

A

GH causes insulin resistance increasing insulin release

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10
Q

Beta2-agonists and insulin

A

beta-2 agonists increase insulin

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11
Q

Signaling pathway for insulin release

A

Glucose enters beta cells and increases ATP/ADP ratio which closes ATP-sensitive K+ channels depolarizing the cell leading voltage-gated Ca2+ channels to open which increases intracellular Ca2+ and leads to insulin exocytosis granules.

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12
Q

What pathways does insulin activates

A

Tyrosine phosphorylation activates Phosphoinositide-3 kinase pathway which exocytoses vesicles containing GLUT-4 and increases glycogen, lipid, and protein synthesis. Through the RAS/MAP kinase pathway it signals for cell growth and DNA synthesis.

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13
Q

Glucagon catabolic effects

A

Increases glycogenolysis, GNG, lipolysis and ketone production

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14
Q

What regulates glucagon

A

Secreted b/c of hypoglycemia. Inhibited by insulin, hyperglycemia, and somatostatin.

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15
Q

CRH releases what

A

ACTH, MSH, beta-endorphin

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16
Q

DA hypo-pituitary axis effect

A

decreases prolactin

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17
Q

Prolactin hypo-pituitary axis effect

A

decreases GnRH

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18
Q

Somatostain pituitary effect

A

decreases GH, TSH

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19
Q

TRH pituitary effect

A

increases TSH and prolactin

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20
Q

Pituitary prolactinoma presents how

A

Amenorrhea/osteoporosis.

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21
Q

Tonic GnRH effects

A

suppresses HPA axis

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22
Q

What regulates prolactin

A

DA from hypothalamus decreases it, TRH increases it. Prolactin leads to more DA secretion which means it limits itself. Estrogens stimulates prolactin secretion. Prolactin decreases GnRH synthesis and release.

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23
Q

GH controls what

A

IGF-1 and somatomedin secretion. Increases insulin resistance. Linear growth and muscle mass

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24
Q

What regulates GH

A

Inc. secretion during exercise and sleep, pulsatile GHRH release. inhibited by glucose and somatostatin.

25
Q

ADH made where

A

Supraoptic nuclei

26
Q

Receptors for ADH

A

V2: serum osmolarity
V1: Blood pressure

27
Q

ADH function

A

inc. urine osmlarity, dec. serum osmolarity: regulation of aquaporin channel transcription in principal cells of renal collecting duct

28
Q

Why is ADH elevated/normal in primary polydipsia?

A

?? Is it the trigger?

29
Q

ADH regulation

A

Primary is osmoreceptors in hypothalamus; secondary is hypovolemia

30
Q

Know adrenal glands chart and table

A

….

31
Q

Congenital adrenal hyperplasia due to what

A

…

32
Q

11-deoxycorticosterone is an active mineralocorticoid, so what is the presentation

A

HTN, low-renin, low cortisol, elevated androgens. XX-virilization.

33
Q

Cortisol mnemonic

A

BIG FIB: BP, Insulin resistance, GNG (lipolysis, proteolysis), Fibroblast activity, Inflammatory and Immune responses, Bone formation

34
Q

how does cortisol increase BP

A

upregulates alpha1-receptors on arterioles leading to inc. susceptibility to NE and E

35
Q

Cortisol and neutrophilia

A

inhibits leukocyte adhesion

36
Q

cortisol and what IL?

A

IL-2 production blocked, TB and candidiasis reactivated

37
Q

Cortisol and bone formation

A

dec. osteoblast activity

38
Q

Where is PTH made

A

Chief cells of parathyroid

39
Q

PTH and kidney regulation of Ca2+ and PO4

A

Ca2+ increased. reabsorp. in DCT

PO4 decreased reabsorp. in PCT

40
Q

PTH and vitamin D

A

Stimulates kidney 1alpha-hydroxylase to increase 1,25-(OH)2-D3 from 25-OH-D3.

41
Q

PTH and bone

A

Inc. production of macrophage colon-stimulating factor and RANK-L (receptor activator of NF-kappaB ligand). RANK-L binds RANk on osteoblasts leading to osteoclast stimulation.

42
Q

Magnesium and PTH

A

Low serum Mg inc. PTH secretion, very low serum Mg lowers PTH secretion

43
Q

Why does very low serum Mg lower PTH secretion

A

????

44
Q

low Mg causes

A

diarrhea, aminoglycosides, diuretics, alcohol abuse

45
Q

Vitamin D effects

A

Feedback inhibits PTH, releases phosphate/calcium from matrix and increases Ca2+/PO4 intestinal absorption

46
Q

Carpopedal spasms?

A

Spasm of the hand and feet seen in hyperventilation, hypocalcemia, and tetany

47
Q

vitamin D sources

A

D3 from sun exposure, D2 from plants. Both converted to 25-OH in liver and to 1,25-(OH)2 (active form) in kidney.

48
Q

24,25-(OH)2 D3

A

Inactive form of Vitamin D

49
Q

Vitamin D regulation

A

Increases activation: Elevated PTH, low serum calcium, low phosphate.
Decreases activation: 1,25-(OH)2 feedback inhibits its own production.

50
Q

Calcitonin source

A

Parafollicular (C cells) cells of thyroid

51
Q

Calcitonin function

A

Dec. bone resorption of Ca2+

52
Q

What increases steroid binding globulins

A

OCPs and pregnancy increase SHBG and TBG (thyroxine binding globulin). Liver failure decreases them.

53
Q

T3 functions mnemonic

A

4 B’s: Brain maturation, Bone growth, Beta1-adrenergic effects, Basal Metabolic rate inc (Na/K ATPase).

Also increases glycogenolysis, GNG, and lipolysis

54
Q

Wolff-Chaikoff effect

A

Excess iodine temporarily inhibits thyroid peroxidase decreasing iodine organification leading to decreased T3/T4 production.

55
Q

What converts T4 to T3

A

5’-deiodinase in peripheral tissue

56
Q

Propylthiouracil MOA

A

inhibits peroxidase and 5’-deiodinase

57
Q

Methimazole MOA

A

inhibits peroxidase only

58
Q

Peroxidase function

A

Oxidation and organification of iodide as well as coupling of MIT and DIT (mono and di-iodotyrosine)

59
Q

What does thyroglobulin do

A

It is the scaffold to which iodine is added, conjugation happens, then proteolysis releases the fully formed thyroxine molecules

Step 1 (34 decks)

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