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HOS Exam 4 > Endocrinology Review Highlights > Flashcards

Endocrinology Review Highlights Flashcards

1
Q

What happens to intracell. cAMP when insulin receptor is activated?

A

Decrease. Insulin receptor is an auto. tyrosine kinase

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2
Q

An example of a receptor with auto-tyrosine kinase is _

A

Insulin receptor

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3
Q

An example of a receptor with docking sites to cytoplasmic tyrosine kinase is _

A

Growth hormone

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4
Q

Steroid receptors are sequestered by _. They bind DNA using _. Where on DNA do they bind?

A

HSP90
Central DNA binding domain
Hormone Response Element

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5
Q

In general, steroid receptors have ligand binding domain in _

A

Carboxy terminal end

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6
Q

The embryological origin of the anterior pituitary is _. Posterior pituitary?

A

Roof of mouth

Neural origin

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7
Q

The major area of the body that responds to ACTH is _

A

Zona fasciculata, cortisol release

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8
Q

The most common cell type in the anterior pit. is _

A

somatotroph

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9
Q

Of the anterior pituitary hormones, which would increase in release if the portal system between the hypothalamus and pituitary was destroyed?

A

Prolactin. Because it is tonically suppressed by PIF

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10
Q

Highest levels of GH secretion is during _

A

Puberty

Second highest in childhood

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11
Q

Before puberty, what is the effect of GH?

A

Via IGF, promotes the linear growth of bone before puberty

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12
Q

Pituitary diabetes can progress to diabetes mellitus. True or false.

A

True. If GH over seccretion occurs for long enough, beta cells in pancreas wear out, stop insulin production

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13
Q

Long loop negative feedback of GH is mediated by _ from _

A

Somatomedin from the liver

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14
Q

The effect of ADH in the kidney is mediated in what region?

A

Collecting ducts

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15
Q

Ethanol and caffeine have what effect on ADH?

A

The inhibit, lead to increased urination

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16
Q

What is the difference between central and nephrogenic diabetes insipidus?

A

Central - Not enough ADH made

Peripheral - ADH can’t function in the kidney (mutant receptor, or Aqp2)

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17
Q

What is the major rgulator of calcium levels in humans?

A

PTH, not calcitonin

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18
Q

What is the major function of iodide trapping?

A

Concentration of iodine in the thyroid

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19
Q

What converts iodide to iodine?

A

Thyroid peroxidase enzyme complex

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20
Q

What is the organification step? What catalyzes it?

A

The reaction of iodine with tyrosine residues thyroglobulin to make MIT and DIT.
Iodinase enzyme

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21
Q

In response to TSH, how is T3/T4 release?

A

Thyroglobulin in proteolyzed to yield free DIT/MIT and free T3/T4

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22
Q

T3/T4 is circulated in the blood bound to _

A

Thyroid binding globulin

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23
Q

What is the effect of mutant deiodinase enzyme?

A

Iodine deficiency,because the enzyme is responsible for recycling iodine from MIT and DIT

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24
Q

What is the function of the monoiodinase enzyme?

A

Conversion to T4 - T3 within the cell

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25
Q

Both the thyroid and steroid receptors are intracellular. How are they different?

A

Steroid receptors homodimerize, while the throid receptor heterodimerizes with RXR

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26
Q

Only form of hyperthryroidism presenting with exophthalmos is _

A

Graves disease, because that is part of the auto-immune response

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27
Q

How does T4 get into the cell?

A

It has specific receptors, it is not lipid soluble

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28
Q

What is myxedema?

A

Hypothyroidism in adults

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29
Q

How does thyroid hormone reduce circulating cholesterol?

A

By increasing its secretion in the bile. It doesn’t decrease its synthesis

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30
Q

Catecholamines increase / decreases glycolysis and lipolysis. True or false?

A

True, trying to make as much energy available

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31
Q

Where are DOPA, dopamine, norepinephrine and epinephrine synthesized?

A

DOPA and DA - Cytoplasm

NE and Epi - Medulla

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32
Q

What is the function of Phenylethanolamine-N-methyl transferase? How is it affected by cortisol?

A

It converts NE to Epi.

Activity is increased by cortisol

33
Q

How does cholesterol enter the cell?

A

Receptor mediated endocytosis via LDL receptor

34
Q

The rate limiting enzyme in steroid synthesis is _

A

Desmolase, converst cholesterol to pregnenolone

35
Q

Where is Pregnenolone converted to progesterone?

A

ER

36
Q

Where is cortisol produced?

A

In the mitochondria

37
Q

Regarding sodium and potassium, what is the effect of low aldosterone?

A

Low sodium, high potassium

38
Q

What is the molecular mechanism of aldosterone (3 proteins)

A

Increase basolateral Na/K ATPase
Increase apical Na channel
Increase apical K channel

39
Q

Where are the mineralocorticoid receptors expressed?

A

Renal epithelial cells

40
Q

2 major stimulants for aldosterone secretion are _

A 
Plasma K+
Plasma hypovolemia (via RAAS)
41
Q

Major negative regulator of aldosterone is _

A

Atrial natiretic peptides from heart

42
Q

What is the cause of Cushing’s disease?

A

ACTH hyper secretion

43
Q

The desmolase challenge to decrease ACTH is a test of _

A

Cushing’s disease

44
Q

A tumor that oversecretes cortisol will lead to _ [high/low] levels of ACTH

A

Low

45
Q

Why does cortisol lead to hypertension on majority of patients?

A

Not enough is converted to cortisone, therefore it stimulates mineralocorticoid receptors to hoard sodium

46
Q

The means by which glucagon and somatostatin modulate insulin secretion is via _

A

GPCRs on the beta cell, increasing and decreasing intracell. PKA activity

47
Q

What type of diabetes is not associated with glucose in the urine?

A

Diabetes insipidus

48
Q

What is the indirect mechanism by which PTH increases calcium reabsorption from the intestines?

A

By increasing levels of the active form of Vit D

49
Q

Chief cells detect calcium levels using what type of receptor?

A

GPCR

50
Q

Vit. D is transported in the blood bound to _

A

Transcalciferin

51
Q

Why does excess vit. D lead to excess plasma phosphate levels?

A

Excess vit D leads to excess calcium, which feeds back to block PTH. therefore phosphate is not secreted

52
Q

The difference between osteomalacia and osteoporosis is _

A

OM - Non-mineralized bone matrix

OP - Bone matrix is resorbed

53
Q

During ovulation, the surge in LH (lesser extent FSH) is preceded by _

A

Surge in GnRH

54
Q

What is the significance of the LH surge??

A

It is required for ovulation

55
Q

What mediates postive feedback to the anterior pituitary to cause the surge in FSH and LH?

A

Progesterone and estradiol

56
Q

What is the role of inhibin B? Inhibin A?

A

B - Blocks FSH, so a second follicle is not released

A - Inhibits both FSH and LH, prevents another ovulation or follicle release

57
Q

What remains the the ovary after ovulation?

A

The corpus luteum

58
Q

What hormone mediates the conversion of the cuboidal cells to stratified cells within the vagina?

A

Estrogen

59
Q

Just know that any effects that helps in female reproductive maturation is mediated by estrogen

A

Done

60
Q

Estrogen and progesterone receptors in mammary tissue can be induced by _

A

Estrogen

61
Q

A hormone that changes the uterine endometrium to prepare for implantation, and blocks uterine contraction is _

A

Progesterone

62
Q

The major hormone that maintains pregnancy is _

A

Progesterone

63
Q

The folicular phase corresponds to the _ phase of the endometrial cycle, while the luteal phase corresponds to the _ phase.

A

Proliferative

Secretory

64
Q

During menopause, what hormones are increased (2)? what are decreased? why ?

A

Increased - FSH and LH
Decreased - Estrogen, progesterone
Loss of negative feed back by estrogens

65
Q

hPTH 1-34 can be given in a pulsatile fashion to women because _

A

Pulsatile PTH apparently stimulates the osteoblasts, not osteoclasts

66
Q

What is the first key hormone of pregnancy? What does it resemble? What is the significance?

A

hCG
LH
Prolongs the activity of the corpus luteum

67
Q

What happens to the estrogen to progesterone ratio close to birth? What is the significance?

A

Increased ratio

Can increase uterine contractility

68
Q

How is the ratio of estrogens to progesterones increased towards the end of pregnany?

A

Estrogens induce the production of progesterone binding protein, reduce the amount of free progesterone

69
Q

Breast maturation during pregnancy is mediated by _, while duct system maturation is mediated by _

A

Estrogen

Progesterone

70
Q

What forms the blood-testis barrier?

A

Sertoli cells

71
Q

True or false, estradiol and testosterone are both required for normal spermatogenesis. Where is estradiol made in the male after puberty?

A

True

Leydig cells

72
Q

What is the function of androgen binding protein? Where is it expressed? What cell type makes it?

A

It binds up androgens

Made by Sertoli cells

73
Q

What 2 hormones dictate whether a fetus is male or female?

A

Testosterone

Mullerian Inhibiting substance

74
Q

Testosterone (not DHEA) directly causes _ (3)

A

Fetal dev. of epididymis, vas def and seminal ves
Musculature and skeleton changes
Spermatogenesis

75
Q

How is testosterone related to prostate cancer?

A

Early on, cancer might be androgen dependent

Later on, becomes androgen independent. Can make treatment of later cancer harder

76
Q

What is eunichism?

A

Lack of testosterone before puberty

77
Q

What is adiposogenital syndrome?

A

Lack of pituitary FSH/LH. Also affects feeding center to voracious appetite is also a problem

78
Q

How does oversecretion of testosterone (e.g. Leydig cell tumor) affect bone growth?

A

Early closure of epiphyseal plate, therefore short stature

79
Q

A teratoma that hypersecretes estrogens can cause _. what of hCG hypersecretion?

A

Estrogen - Breast dev. in males

hCG - Increased testosterone and virilization

HOS Exam 4 (7 decks)

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