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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
ADH made where
Supraoptic nuclei
26
Receptors for ADH
V2: serum osmolarity V1: Blood pressure
27
ADH function
inc. urine osmlarity, dec. serum osmolarity: regulation of aquaporin channel transcription in principal cells of renal collecting duct
28
Why is ADH elevated/normal in primary polydipsia?
?? Is it the trigger?
29
ADH regulation
Primary is osmoreceptors in hypothalamus; secondary is hypovolemia
30
Know adrenal glands chart and table
....
31
Congenital adrenal hyperplasia due to what
...
32
11-deoxycorticosterone is an active mineralocorticoid, so what is the presentation
HTN, low-renin, low cortisol, elevated androgens. XX-virilization.
33
Cortisol mnemonic
BIG FIB: BP, Insulin resistance, GNG (lipolysis, proteolysis), Fibroblast activity, Inflammatory and Immune responses, Bone formation
34
how does cortisol increase BP
upregulates alpha1-receptors on arterioles leading to inc. susceptibility to NE and E
35
Cortisol and neutrophilia
inhibits leukocyte adhesion
36
cortisol and what IL?
IL-2 production blocked, TB and candidiasis reactivated
37
Cortisol and bone formation
dec. osteoblast activity
38
Where is PTH made
Chief cells of parathyroid
39
PTH and kidney regulation of Ca2+ and PO4
Ca2+ increased. reabsorp. in DCT | PO4 decreased reabsorp. in PCT
40
PTH and vitamin D
Stimulates kidney 1alpha-hydroxylase to increase 1,25-(OH)2-D3 from 25-OH-D3.
41
PTH and bone
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
Magnesium and PTH
Low serum Mg inc. PTH secretion, very low serum Mg lowers PTH secretion
43
Why does very low serum Mg lower PTH secretion
????
44
low Mg causes
diarrhea, aminoglycosides, diuretics, alcohol abuse
45
Vitamin D effects
Feedback inhibits PTH, releases phosphate/calcium from matrix and increases Ca2+/PO4 intestinal absorption
46
Carpopedal spasms?
Spasm of the hand and feet seen in hyperventilation, hypocalcemia, and tetany
47
vitamin D sources
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
24,25-(OH)2 D3
Inactive form of Vitamin D
49
Vitamin D regulation
Increases activation: Elevated PTH, low serum calcium, low phosphate. Decreases activation: 1,25-(OH)2 feedback inhibits its own production.
50
Calcitonin source
Parafollicular (C cells) cells of thyroid
51
Calcitonin function
Dec. bone resorption of Ca2+
52
What increases steroid binding globulins
OCPs and pregnancy increase SHBG and TBG (thyroxine binding globulin). Liver failure decreases them.
53
T3 functions mnemonic
4 B's: Brain maturation, Bone growth, Beta1-adrenergic effects, Basal Metabolic rate inc (Na/K ATPase). Also increases glycogenolysis, GNG, and lipolysis
54
Wolff-Chaikoff effect
Excess iodine temporarily inhibits thyroid peroxidase decreasing iodine organification leading to decreased T3/T4 production.
55
What converts T4 to T3
5'-deiodinase in peripheral tissue
56
Propylthiouracil MOA
inhibits peroxidase and 5'-deiodinase
57
Methimazole MOA
inhibits peroxidase only
58
Peroxidase function
Oxidation and organification of iodide as well as coupling of MIT and DIT (mono and di-iodotyrosine)
59
What does thyroglobulin do
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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