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ENDOREPRO MODULE > Hyper/Hypo Calcemia Plus General Physiology > Flashcards

Hyper/Hypo Calcemia Plus General Physiology Flashcards

0
Q

Describe the normal equilibrium balance between serum ionized Ca and PTH production by the parathyroid gland?

A

A small decrement in serum ionized calcium will STIMULATE PTH release.
A small increment in serum ionized calcium will SUPPRESS PTH release.

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1
Q

What is the dominant hormonal control of serum Calcium?

A

PTH

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2
Q

What are the three direct effects of PTH release on Ca homeostasis?

A

Stimulate osteoclast-mediated release of Ca from bone.
Decrease renal Ca clearance
Stimulate renal 1-alpha hydroxylase to convert calcidiol to calcitriol.

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3
Q

More calcitriol in the system leads to what physiologic phenomenon?

A

Enhances gut absorption of Ca

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4
Q

PTH secretion is STIMULATED by an elevated or decline in serum phosphate?

A

Elevated serum phosphate

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5
Q

What is the phosphaturic effect?

A

PTH directly reduces the renal tubular reabsorption of phosphate from glomerular filtrate.

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6
Q

Place Vitamin D, calcitriol and calcidiol in order of potency.

A

Calcitriol&raquo_space; calcidiol > Vitamin D.

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7
Q

What is the prominent influence of the Vitamin D group (calciferols) of steroid hormones?

A

Promote gut absorption of BOTH calcium and phosphate.

Leads to an increase SERUM level of both.

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8
Q

What cells produce calcitonin?

A

C-cells of the thyroid

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9
Q

What is the function of calcitonin?

A

Opposed the PTH effect on bone -> promotes uptake of calcium by bone.
Calcitonin also promotes renal calcium excretion.

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10
Q

What are the thyroid hormones?

A

thyroxine and triiodothyronine

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11
Q

What are the three forms of Calcium in serum?

A

Protein bound.
Ionized.
Complexed (bound weakly to bicarbonate, HPO4, citrate, or lactate.

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12
Q

What is the precursor molecule for all steroid hormones?

A

Derived from cholesterol

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13
Q

Can steroid hormones be stored within intracellular vesicles?

A

No. Steroid hormones can diffuse freely through lipid membranes and cannot be stored within intracellular vesicles. Because of this they are produced continually.

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14
Q

Since steroid hormones are lipid soluble, they must circulate bound to what?

A

Plasma proteins.

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15
Q

T/F Steroid hormones are freely filtered by the kidney.

A

FALSE. They are protein-bound. They have a long half-life relative to most peptide hormones.

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16
Q

Where are steroid hormones primarily metabolized?

A

By the liver.

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17
Q

What are the sex steroids?

A

Testosterone, progesterone, estrogen.

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18
Q

What are the adrenal steroids?

A

Cortisol

Aldosterone.

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19
Q

What is the precursor molecule for the thyroid hormones?

A

Thyroid hormones are derived from amino acid TYROSINE rather than cholesterol

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20
Q

What are the six hypothalamic hormones?

A 
CRH
GnRH
TRH
GHRH
Somatostatin
Dopamine
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21
Q

What is the physiologic action of CRH?

A

Stimulates ACTH secretion from the anterior pituitary.

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22
Q

What does ACTH stand for?

A

adrenocorticotropin hormone

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23
Q

What is the physiologic action of GnRH?

A

Stimulates gonadotropin secretion from anterior pituitary.

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24
Q

What is the physiologic action of TRH?

A

Stimulates TSH secretion from anterior pituitary.

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25
Q

What does TRH stand for?

A

Thyrotropin releasing hormone

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26
Q

Physiologic action of GHRH?

A

Stimulates growth hormone secretion from anterior pituitary

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27
Q

Somatostatin physiologic action?

A

Inhibits GH secretion from anterior pituitary.

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28
Q

Dopamine physiologic action in terms of endocrinology?

A

Inhibits prolactin secretion from anterior pituitary.

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29
Q

Name the 6 anterior pituitary hormones?

A 
FSH
LH
ACTH
TSH
Prolactin
GH
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30
Q

ACTH physiologic action?

A

Stimulates glucocorticoid and androgen synthesis in the adrenal cortex.

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31
Q

TSH physiologic actions?

A

Stimulates thyroid hormone synthesis in thyroid gland.

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32
Q

LH physiologic action?

A

Stimulates testosterone secretion by Leydig cells in testes.
Stimulates progesterone synthesis in women
Stimulates ovulation and corpus luteum development.

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33
Q

FSH physiologic function?

A

Stimulates spermatogenesis in testes.

Stimulates estrogen synthesis by granulosa cells in ovarian follicles.

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34
Q

Prolactin physiologic actions?

A

Stimulates breast maturation and milk letdown.

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35
Q

What are the posterior pituitary hormones?

A

ADH

oxytocin

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36
Q

ADH physiologic function?

A

Stimulates water absorption from the distal nephron.

37
Q

Oxytocin

A

Stimulates uterine contraction during labor.

38
Q

What are the two thyroid hormones?

A

Thyroxine (T4)

Triiodothyronine (T3)

39
Q

What is T4’s physiologic function?

A

Prohormone that becomes bioactive on peripheral conversion to T3.

40
Q

T3 physiologic action?

A

Increases basal metabolic rate by up-regulating expression and insertion of Na+, K+-ATPase pump

41
Q

What are the adrenal cortex hormones?

A

Aldosterone
Cortisol
DHEA (dehydroepiandrosterone)

42
Q

What are the physiologic functions of cortisol?

A

MAINTAIN GLUCOSE for glucose-dependent tissues during fasting state by promoting hepatic gluconeogenesis, peripheral resistance to insulin, lipolysis in adipose tissue.

43
Q

DHEA function?

A

Converted to testosterone in peripheral tissues.

44
Q

What are the adrenal medulla hormones?

A

Epinephrine

45
Q

What are the ovarian hormones?

A

Estrogen

46
Q

Testicular hormones?

A

Testosterone

DHT

47
Q

Pancreatic hormones?

A

Insulin
Glucagon
Somatostatin
Vasoactive-intestinal peptide

48
Q

What two hormone binding proteins’ plasma levels increase during pregnancy?

A

Thyroid binding globulin
Transcortin
Estrogen increases their synthesis in the liver. This will increase total thyroid and cortisol hormone but NOT free thyroid and cortisol hormone.

49
Q

In primary endocrine diseases, where is the defect?

A

Defect is in the endocrine organ.

50
Q

In secondary endocrine diseases, where is the defect?

A

Defect is in the pituitary gland.

51
Q

In tertiary endocrine diseases, where is the defect?

A

The defect is in the hypothalamus.

52
Q

What is the overall function of the hypothalamic-pituitary-adrenal axis?

A

Function is to maintain physiologically appropriate plasma levels of the hormone cortisol.

53
Q

ACTH acts on adrenal cortex to stimulate the synthesis and secretion of glucocorticoids and androgens. Can androgens feedback-inhibit ACTH secretion?

A

NO, androgens to not feedback-inhibit the pituitary.

54
Q

What physiological processes is cortisol secretion stimulated by?

A 
Hypoglycemia
Stressful conditions (surgery), when the sympathetic nervous system is also stimulated
55
Q

What is cortisol sometimes referred to as?

A

Stress hormone

56
Q

A tumor of the adrenal gland that autonomously hypersecretes cortisol will have what sort of effect on CRH, ACTH and cortisol?

A

It still will negatively feedback on the hypothalamus and anterior pituitary, resulting in decreased ACTH secretion. Patient will be hypercortisolemic with a low ACTH, implying an etiology is adrenal in origin.

57
Q

When are cortisol levels highest?

A

Early morning, owing to the early-morning surge of ACTH.

58
Q

What is the rate limiting step in adrenal steroid synthesis?

A

Conversion of cholesterol to pregnenolone.

59
Q

Which adrenal steroid is synthesized in the zona glomerulosa? zona fasciculata? zona reticularis?

A

Remember “GFR” The deeper you go the sweeter it gets.
G= Mineralcorticoids
F= Cortisol
R= androgens

60
Q

The secretion of aldosterone is regulated by what?

A

Plasma concentrations of Potassium and angiotensin II, with the latter increasing conversion of corticosterone to aldosterone by stimulation of 18-hydroxylase.

61
Q

How does cortisol stimulate hepatic gluconeogenesis?

A

Promotes muscle breakdown, release a.a. Ala and Asp into gluconeogenic pathway
Stimulates synthesis of hepatic gluconeogenic enzymes
Stimulates lipolysis in adipose tissue -> helps maintain plasma levels of glycerol and fatty acids in fasting state

62
Q

Metabolic actions of cortisol?

A

Affects liver, muscle, adipose tissue.
Generally catabolic
Stimulates gluconeogenesis
Preserves plasma glucose.

63
Q

Does cortisol increase or decrease BP?

A

Increase.

64
Q

At higher concentrations, cortisol can exert what sort of effects on the kidney?

A

Mineralocorticoid effect because it is similar in structure to aldosterone.

65
Q

Does cortisol have inflammatory or anti-inflammatory effects?

A

Anti-inflammatory.

Inhibits activity of phospholipase A -> decreased arachidonic acid -> decreased prostaglandins and leukotrienes.

66
Q

Does cortisol weaken or strengthen bone at supraphysiologic levels?

A

Cortisol WEAKENS bone by inhibiting osteoblasts and stimulating osteoclasts.

67
Q

Name four things that cortisol promotes and the pathophysiologic conditions associated with each.

A

Hyperglycemia -> Diabetes mellitus
Muscle breakdown -> muscle wasting
Bone Loss -> osteoporosis
Plasma volume expansion -> hypertension

68
Q

What is the most common endogenous source of elevated cortisol?

A

ACTH-hypersecreting tumor of the pituitary, also known as Cushing DISEASE

69
Q

What does the dexamethasone test determine? How is it done?

A

Test differentiates between pituitary Cushing and paraneoplastic secretion ACTH in patient with hypercortisolism and elevated ACTH.
Pituitary Cushing - has feedback inhibition
Ectopic Cushing - not controlled thru feedback inhibition

70
Q

What is the most common cause of hypocortisolism?

A

Iatrogenic. Abrupt cessation of chronically administered steroids.

71
Q

In primary adrenal insufficiency, are ACTH levels high or low?

A

High.

72
Q

What is a major cause of chronic adrenal insufficiency?

A

Autoimmune destruction of the adrenals (Addison’s Disease), tuberculosis or metastatic cancer involving the adrenals can also be a cause of chronic adrenal insufficiency.

73
Q

Signs and symptoms of adrenal insufficiency?

A

Hypotension
Salt Wasting
High levels of ACTH
hyperpigmentation of the skin

74
Q

Congenital Adrenal Hyperplasias (CAH) are characterized by enzymatic defects in what pathway?

A

Cortisol biosynthetic pathway.

75
Q

What is the most common form of CAH?

A

21-hydroxylase deficiency

76
Q

Why does 11-hydroxylase deficiency produce salt retention and hypertension?

A

Because of an increase in 11-deoxycorticosterone, which is proximal to the enzyme block.

77
Q

What is the main function of the hypothalamic-pituitary-thyroid axis?

A

Maintain physiologically appropriate plasma levels of thyroid hormones T3 and T4

78
Q

TSH stimulates secretion of T3 and T4 from what cells in the thyroid gland?

A

Follicular cells

79
Q

What hormone, secreted by the parafollicular cells in the thyroid gland, is NOT regulated by the hypothalamus-pituitary-thyroid axis?

A

Calcitonin

80
Q

Describe the steps in the synthesis of thyroid hormone

A

(I-) internalized (TSH mediated)
(I-) to I2
I2 attached to thyroglobulin -> MIT DIT (TSH mediated)
Couple MIT + DIT into T4 and T3
Endocytosis of thyroglobulin from colloid
Hydrolytic cleavage of T3 and T4 from thyroglobulin; diffusion of T4 and T3 into plasma (TSH mediated)

81
Q

Common drugs to treat hyperthyroidism?

A

Propylthiouracil (PTU)

Methimazole

82
Q

T4 is more or less potent than T3?

A

T4 is much LESS potent than T3 but has a longer plasma half-life than T3.

83
Q

What enzyme converts T4 to T3?

A

5’-monodeiodinase.

84
Q

Is T4 or T3 responsible for feedback inhibition of pituitary and hypothalamus?

A

T4; much more abundant

85
Q

What systems do thyroid hormones act on?

A

Metabolism, Bone, CNS, Skin, CV system, Intestines.

86
Q

What is the most common cause of hyperthyroidism?

A

Graves Disease (diffuse toxic goiter)

87
Q

Most common type of secondary hyperthyroidism?

A

Pituitary Adenoma

88
Q

Most common cause of tertiary hyperthyroidism?

A

Hypothalamic tumor.

89
Q

What is the classical presentation of Grave’s Disease?

A

thyrotoxicosis (symptoms of hyperthyroidism)
diffuse goiter
ophthalmopathy (exophthalmos)
dermopathy (pretibial myxedema)

ENDOREPRO MODULE (11 decks)

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