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PHYSIOLOGY II > Lecture 11: Intro to Endocrine > Flashcards

Lecture 11: Intro to Endocrine Flashcards

1
Q

the endocrine system is part of the ________ control system

A

extrinsic

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2
Q

hormones regulate processes that require ______ rather than speed

A

duration

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3
Q

what is a hormone

A

an endocrine signaling molecule

a chemical messenger released from ductless glands or neurons into the bloodstream

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4
Q

what are the 5 main HP axes

A

Adrenal (HPA)
Thyroid (HPT)
Gonadal (HPG)
Liver (HPL)
prolactin

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5
Q

what are 2 hormones regulated outside the hypothalamus pituitary axis

A

insulin (blood sugar)
parathyroid hormone (Ca)

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6
Q

pancreatic B cells release _____ in direct response to elevated glucose

A

insulin

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7
Q

what tissue have exclusive endocrine function

A

pituitary
thyroid glands
parathyroid glands
adrenal glands

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8
Q

what 3 things can hormones be made of

A

amines
steroids
peptides

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9
Q

what hormones are made from amines

A
  • epinephrine(adrenaline) from adrenal medulla
  • thyroid hormone (T3+t4) from tyrosine
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10
Q

what hormones are made from peptides

A

CRH, ACTH, GH, oxytocin, vasopressin, insulin, glucagon, etc

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11
Q

Epinephrine is polar/nonpolar and hydrophobic/hydrophilic?

A

polar
hydrophilic

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12
Q

thyroid hormones are polar/nonpolar and hydrophobic/hydrophilic?

A

nonpolar, hydrophobic

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13
Q

peptides are polar/nonpolar and hydrophobic/hydrophilic?

A

polar
hydrophilic

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14
Q

what are the 3 qualities of peptide hormones

A

polar
hydrophilic
made from amino acids

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15
Q

what is Pro-Opiomelanocortin (POMC)

A

precursor peptide to several hormones and signaling molecules

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16
Q

PC1 is expressed solely in ______________ and produces _______

A

pituitary corticotropes and produces ACTH

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17
Q

PC1 and PC2 are expressed in _______ and produce what

A

melanotrophs
produce α-MSH, β-MSH and βendorphin, but not ACTH

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18
Q

3 qualities of steroid hormones

A

non polar
lipophilic
made from cholesterol

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19
Q

steroids are synthesized from _______ in gonads, adrenal cortex, adipose, placenta and brain

A

cholesterol

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20
Q

estrogen and testosterone are _____ hormones, synthesized in the ______

A

steroid hormones
gonads

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21
Q

cortisol and aldosterone are what type of hormones and where are they synthesized?

A

cortisol - glucocorticoid
aldosterone - mineralocorticoid
adrenal cortex

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22
Q

cholesterol is transported to the mitochondria and localized by…

A

steroidogenic acute regulatory protein (STaR)

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23
Q

cholesterol is converted to pregnenolone by ________, primarily activated by ACTH

A

cholesterol desmolase (CYP11A1)

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24
Q

what is cholesterol derived from

A
  • LDL from diet
  • Hydrolysis of cholesterol esters from vesicles
  • De novo synthesis from acetyl CoA
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25
Q

Mobilization of cholesterol into the cell is mediated by what

A

ACTH
Angiotensin 2
K+ channels in the zona glomerulosa and other zones in the adrenal cortex

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26
Q

All steroid hormones have the same initial step of biosyntheses: the conversion of _______ to ________

A

cholesterol to pregnenolone

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27
Q

what is the effect of steroid hormones being nonpolar?

A

they don’t dissolve well in blood + usually require assistance in moving through the blood in the form of a carrier protein

  • only 1% of steroid hormones exist freely in blood, the rest are bound to a large protein like albumin
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28
Q

what does it mean for steroid hormones to be lipophilic?

A

they can easily cross into the plasma membrane of cells

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29
Q

what does it mean for peptide hormones to be hydrophobic?

A

they can be dissolved easily within the blood

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30
Q

what is the effect of peptide hormones being polar?

A

they cannot pass through PM of cells, must signal cells by binding to receptors on the plasma membrane.

31
Q

where does the main signal for steroid hormone production come from

A

the pituitary

32
Q

ACTH coming from the pituitary targets _______ glands to activate the production of steroid signals

A

adrenal glands

33
Q

The different directions of steroid biosynthesis pathways (whether you end up w/ aldosterone, cortisol or estradiols) depend on what

A

the presence of certain enzymes

34
Q

can there be a response within a target cell/tissue to a hormone if the target cell lacks a receptor

A

no receptor = no response

35
Q

Most tissues are affected by multiple hormones and the physiological response to these hormones depends on what

A

the combination of hormone receptors in each cell and the diversity of cells in a tissue

36
Q

example of a hormone that is also a neurotransmitter

A

norepinephrine

released into circulation by adrenal glands but also released as an excitatory NT in brain

37
Q

Hormone receptors are _______ that bind to the hormone and initiate ________

A

proteins, initiate a cellular response

38
Q

where in cells are hormone receptors found

A

cell membranes
cytoplasm (intracellular)
cell nuclei

39
Q

what is negative feedback

A

when a change in a controlled variable triggers a change in the opposite direction

increase in a hormone blocks further release of that hormones by an inhibiting cascade of trophic hormones

*the main mechanism by which homeostasis is regulated

40
Q

in the neural pathway, neurons project to the _________ to release hormones

A

neurohypophysis

41
Q

what are the hormones of the neural pathway? Where are they released from

A

oxytocin and vasopressin
posterior pituitary

42
Q

in the anterior pathway, releasing hormones are released into the _____ system to release trophic hormones from the anterior pituitary system

A

blood portal system

43
Q

what pathways (neural or anterior) contains the 5 HP-Axes

A

anterior pathway

44
Q

what are the 3 kinds of steroid hormones released by the adrenal cortex

A

**Glucocorticoids **(cortisol, corticosterone (birds, rodents)
- regulate blood glucose
**Mineralocorticoids **(aldosterone)
- regulate minerals and Na
Weak Androgens (androstenedione, DHEA)
- adro=male

45
Q

where is Corticotropin releasing hormone (CRH) released from within the HPA axis

A

paraventricular nucleus of the hypothalamus (its axons go to the posterior pituitary)

46
Q

what is the pathway CRH travels

A
  1. releasd from the paraventricular nucleus of the hypothalamus
  2. travels via the blood portal to the anterior pituitary
  3. stimulates corticotropes to release ACTH
47
Q

what inhibits CRH

A

ACTH

48
Q

what sitmulates adrenal growth

A

ACTH

49
Q

what hormone has a short feedback loop

A

ACTH

50
Q

What hormone has a long feedback loop

A

Cortisol

51
Q

what hormone transfers cholesterol to the mitochrondria and activates cholesterol desmolase

A

ACTH

52
Q

what does cortisol inhibit and how

A

directly inhibits CRH and ACTH release
inhibits ACTH release through inhibiting CRH

53
Q

the primary effect of cortisol is to increase _________ by enhancing ________ in the liver

A

increased blood glucose by enhancing gluconeogenesis

54
Q

ACTH targets the ?

A

adrenal cortex

55
Q

secretion of this hormone is essential for life and is esp. critical during lean times when survival is compromised

A

Cortisol

56
Q

besdies increasing blood glucose, what other important things can cortisol do

A
  • increase protein catabolism to provide amino acids
  • decrease protein synthesis
  • increase lipoysis in fat
  • Diabetogenic effect: decrease glucose uptake by tissues to make blood sugar rise
  • decrease sensitivity to insulin
57
Q

what are the effects of cortisol on cardiovascular tissue

A
  • maintains normal BP
  • upregulates alpha -1 adrenergic receptor
  • enhances vasoconstrictive responses
58
Q

what are the effects of cortisol on immune function

A
  • anti inflammaotry effects
  • reduced Phospholipase A, IL-2, histamine and serotinin
  • inhits proliferation of T cells
59
Q

what are the effects of cortisol on bone

A
  • inhibits synthesis of type 1 collagen, a major structural component of bone matrix
  • decreases oseoblasts
  • decreases intestinal Ca absorption
60
Q

what are the effects of cortisol on connective tissue and muscle

A
  • inhibits fibroblast proliferation and collagen formation
  • high amounts of CORT cause thin skin and impaired tissue support
  • increased proteolysis in muscle leading to weakness
61
Q

typical times during which CORT is elevated

A
  • upon waking up (declines through rest of day)
  • when hungry
  • when stressed (increases blood glucose)
62
Q

physical presentation of Cushing’s

A
  • abnormal adipose deposits
  • thinning and bruising of skin
  • muscle atrophy of legs
63
Q

Cushing’s Syndrome is due to?

A

primary adrenal hyperplasia (overactive adrenal glands)

64
Q

In Cushing’s Syndrome, ACTH is _____ and CORT is _____

A

ACTH is LOW (b/c lack of negative feedback loop)
CORT is HIGH

65
Q

Cushing’s Disease is due to?

A

secondary excess ACTH from the pituitary or ACTH secreting cells in the lungs

same symptoms as cushing’s syndrome but the disease results from overactive pituitary secretion of ACTH

66
Q

in Cushing’s Disease, ACTH is ___ and CORT is _____

A

ACTH is HIGH
CORT is HIGH

67
Q

clinical symptoms of Cushing’s

A
  • hyperglycemia
  • hypertension
  • increase protein catabolism
  • muscle wasting
  • central obesity
  • thin skin
  • bruising
68
Q

Addison’s Disease is characterized by a decreased sysnthesis of what

A

of all adrenocortical hormones (Cortisol, Aldosterone, Androgens) as a result of autoimmune destruction of tissue

dogs, cats, sometimes horses

69
Q

a loss of cortisol (such as in Addison’s) results in?

A
  • stress induced hypoglycemia
  • muscle weakmess
  • weightloss
  • reduced HPA feedback —> hyperpigmentation (lack of neg. feedback increases ACTH secretion which contains melanocyte stimulating hormone)
70
Q

a loss of aldosterone (such as in Addison’s) results in?

A
  • hyperkalemia
  • hypotension
  • metabolic acidosis
  • salt cravings
71
Q

a loss of androgens (such as in Addison’s) results in

A

decreased libido for women

72
Q

how to test for adrenal cortex function?

A

ACTH stimulation test
- administer exogenous ACTH
- measure CORT at baseline and then 30 min later
- would exoect CORT increase 2x
- subnormal responses indicate primary adrenal insufficiency = adrenals don’t responst to ACTH

73
Q

Treatment for primary adrenal insufficiency

A

Glucocorticoids (prednisolone)
mineralocorticoid txt (flucocotisone)

PHYSIOLOGY II (17 decks)

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