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Veterinary Physiology > Adrenal Medulla & Cortex > Flashcards

Adrenal Medulla & Cortex Flashcards

1
Q

What does the adrenal cortex produce?

A

mineralocorticoids
glucocorticoids
androgens

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2
Q

What does the adrenal medulla produce?

A

epinephrine
norepinephrine

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3
Q

The adrenal medulla has ______ innervation, with preganglionic fibers originating in the ________

A

sympathetic (specialized sympathetic ganglion)
thoracic spinal cord

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4
Q

What cells secrete catecholamines? What do they produce?

A

chromaffin
Epi
NE

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5
Q

Epi acts on which alpha and beta receptors?

A

ALL

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6
Q

NE acts on which alpha and beta receptors?

A

alpha 1 & 2, beta-1

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7
Q

The predominant catecholamine is _____ at what %?

A

epinephrine
80%

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8
Q

What converts NE into Epi? Under what influence?

A

phenylethanolamine-N_methyltransferease (PNMT)
influence of cortisol

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9
Q

Cortisol is made in the _____

A

cortex
so it reaches medulla in high concentrations

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10
Q

Epi is stored in _______ and released when activated by [SNS/PSNS]

A

granules
SNS

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11
Q

ALL epi originates from the _____

A

adrenal medulla

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12
Q

Most NE originates from _____ & ______. Only a small amount from the adrenal medulla

A

sympathetic nerve terminals
brain

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13
Q

What are the target tissues of catecholamines?

A

muscle cells
liver

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14
Q

Most metabolism of catecholamines occurs in the ____ & _____

A

liver
kidneys

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15
Q

What regulates catecholamine secretion?

A

fight or flight responses (danger, pain, hypervolemia, hypotension, anorexia, etc)

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16
Q

What are the effects of catecholamines?

A

increased heart rate, cardiac output, blood pressure
redistribution of blood towards skeletal muscle
increased respiration (ventilation and dilation in airways)
increased blood glucose

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17
Q

During fight or flight activation, blood is shunted away from what systems? What metabolically happens?

A

GIT
reproduction
urinary
increase in lipolysis and maybe gluconeogenesis

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18
Q

What are the zones of the cortex?

A

zona glomerulosa
zona fasciculata
zona reticularis

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19
Q

What hormone is in the zona glomerulosa?

A

aldosterone

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20
Q

What hormone(s) is/are in the zona fasciculata?

A

cortisol - lots of mammals
corticosterone - rat, mouse, rabbit

21
Q

What hormone(s) is/are produced in the zona reticularis?

A

androgen precursors
DHEA —> dehydroepiandosteroine
andostendoine

22
Q

What is the precursor for all steroids?

A

cholesterol

23
Q

Steroid hormone production is catalyzed by

A

cytochrome P450 systems in mitochondria and endoplasmic reticulum

24
Q

Cholesterol comes from…

A

diet
MOST from circulation
some de novo synthesis

25
Q

What enzyme converts cholesterol to pregnenolone?

A

cholesterol desmolase (using ACTH from anterior pituitary gland)

26
Q

What is the rate-limiting step in steroid hormone production?

A

conversion of cholesterol to pregnenolone
- nothing is stored in the cell, so conversion via cholesterol desmolase is a critical step

27
Q

All layers of the adrenal cortex contain what enzyme?

A

cholesterol desmolase

28
Q

The direction of steroid hormone production pathway depends on presence/absence of ______ to catalyze modifications

A

enzymes

29
Q

What enzymes are required to synthesize aldosterone in the zona glomerulosa?

A

aldosterone synthase
cholesterol desmolase

30
Q

Which enzyme is under the influence of angiotensin II?

A

aldosterone synthase

31
Q

What are the functions of aldosterone?

A

long-term regulation of blood pressure
exhibits diurnal pattern

32
Q

The primary regulation for aldosterone occurs via changes in ________

A

ECF volume via RAAS pathway
changes in blood potassium

33
Q

Aldosterone is transported in the BLOOD by

A

aldosterone-binding globulin
transcortin
albumin

34
Q

A decrease in ECF leads to a decrease in …? Then leads to an increase in?

A

renal blood perfusion
renin secretion by kidney

35
Q

What also stimulates aldosterone secretion?

A

increase in blood K+ concentration
- depolarizes adrenal cells to open CA2+ changes to stimulate aldosterone

36
Q

The first step towards cortisol (after converted to pregnenolone) is what enzyme?

A

17alpha-hydroxylase

37
Q

What is the final enzyme in the cortisol pathway? What does it convert?

A

11beta-hydroxylase
converts 11-deoxycortisol to cortisol

38
Q

Cortisol is regulated by what?

A

hypothalamic-pituitary adrenal axis
CRH - hypothalamus
ACTH - ant pituitary

39
Q

How is cortisol transported in blood?

A

transcortin

40
Q

Cortisol is metabolized where and how?

A

liver
excreted in urine using glucuronides

41
Q

List factors that stimulate ACTH secretion

A

stress - hypoglycemia, infections, fever (physiological)
low cortisol
ADH

42
Q

List factors that inhibit ACTH secretion

A

high cortisol
exogenous steroids
somatostatin
dopamine (tonic inhibition at the pars intermedia in horses)

43
Q

Once cortisol is released, it provides ____ to [inhibit/stimulate] ACTH release. It [quickens/slows] ACTH synthesis, which takes _____

A

long-loop feedback - minutes
inhibit
slows feedback
hours

44
Q

Cortisol also has a ______ to [stimulate/block] CRH release

A

long-loop feedback
block

45
Q

Once ACTH is released, it provides ____ to [inhibit/stimulate] CRH release.

A

short-loop feedback
inhibits

46
Q

What is the mechanism of action of cortisol at the tissue level?

A

cortisol binds type II glucocorticoid receptor in cytosol
receptor-hormone complex moves into nucleus and binds another receptor on DNA
active gene transcription and translation

47
Q

The half-life of aldosterone is ____, and the half-life for cortisol is ______

A

20 min
60-90 min

48
Q

Aldosterone exhibits a ____ pattern. What does this mean?

A

diurnal
lowest levels of hormone around midnight and highest at awakening

49
Q

Cortisol exhibits a _____ pattern. What does this mean?

A

pulsatile / episodic
Wille keep ~2 hrs before awakening

Veterinary Physiology (26 decks)

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