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71 terms

Hormones of the Adrenal Cortex (77)

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Name the 4 zones of the adrenal gland.
zona glomerulosa

zona fasciculata

zona reticularis

adrenal medulla
What is secreted by the zona glomerulosa?
mineralcorticoids (aldosterone)
What is secreted by the zona fasciculata?
glucocorticoids (cortisol)
What is secreted by the zona reticularis?
androgens (DHEA, androstenedione)
What is secreted by the adrenal medulla?
epinephrine

NE
How does cortisol affect CRH and ACTH secretion?
decreases both; 1
Describe the relase of corticotropin releasing hormone.
pulsatile, diurnal
During what time of day is cortisol release the greatest?
early morning

*plasma cortisol levels measured early morning; 2
Where is CRH synthesized?
paraventricular nucleus of hypothalamus
Is the half-life of CRH long or short?
short
What type of G protein is the CRH receptor?
Gs; 3
What is the precursor molecule for ACTH?
pro-opiomelanocortin (POMC); 4
What type of G protein is the ACTH receptor?
Gs; 5
What protein activates a cholesterol channel in the mitochondria, allowing it to enter and be converted into pregnenolone? In which zones does this protein act upon?
StAR; 6 (Steroidal acute regulatory protein)

zona fasciculata

zona reticularis
What is the short-term effect of ACTH?
conversion of cholesterol into pregnenolone
Name 2 long-term effects of ACTH.
transcription of synthesis enzymes

increase in number of LDL receptors
Describe the release of ACTH.
pulsatile and diurnal
Why is aldosterone production exclusive to the zona glomerulosa?
alone possesses aldosterone synthase
Name a hormone and ion that increase StAR in the zona glomerulosa.
angiotensin 2

high K+
What type of G protein is the angiotensin 2 receptor in the zona glomerulosa?
Gq; 7
How does high extracellular K+ affect synthesis and release of aldosterone?
increases synthesis and release of aldosterone; 8
How does aldosterone affect sodium, water, and K+ reabsorption/secretion?
9
Which parts of the nephron are affected by aldosterone?
principal cell of DCT/collecting duct
Name 3 channels in the principle cells of the distal convoluted tubule/collecting duct that are enhanced by aldosterone.
sodium pump

ENaC

K+ (ROMK) channels; 10
How does the body prevent cortisol from exerting a large mineralcorticoid effect?
11-beta-hydroxysteroid dehydrogenase converts cortisol into cortisone
Name a herb that blocks the enzyme 11-beta-hydroxysteroid dehydrogenase.
licorice
How can licorice affect sodium retention?
increase sodium retention, leading to hypertension--"Mineralcorticoid excess syndrome"
How does aldosterone secretion affect angiotensin 2 release?
negative feedback; 11
Explain how compensatory mechanisms in congestive heart failure can exacerbate the disease.
12
Name a cause of hypersecretion of aldosterone.
Conn's syndrome due to glomerulosa tumor
Describe K+, renin levels, and blood pressure in Conn's syndrome.
low renin levels

hypokalemia

increased blood pressure
Conn's syndrome Rx
aldosterone antagonists and surgical resection
Describe hydration, blood pressure, [Na], and [K] in hyposecretion of aldosterone.
dehydration

hypotension (marked postural hypotension due to low blood volume)

hyperkalemia

hyponatrema
Describe blood aldosterone, renin, and angiotensin 2 in hyposecretion of aldosterone.
decreased aldosterone

increased renin

increased angiotensin 2
Name the disorder: autoimmune disorder affecting the whole adrenal cortex.
Addison's disease
During what time of day is release of cortisol the greatest?
early morning
Name the plasma protein bound to cortisol in the blood.
cortisol binding globulin (transcortin)
Where in/on the cell are cortisol receptors found?
inside the cytoplasm. 13
Review actions of glucocorticoids.
14
How does cortisol affect insulin?
decreases effects of insulin on glucose uptake
How does cortisol affect protein metabolism?
increases proteolysis in all cells (except the liver)
How does cortisol affect fat metabolism?
increases lipolysis and mobilizes fatty acids
How does cortisol affect the immune system and inflammation?
immunosuppressive

anti-inflammatory
How does cortisol affect lysosomes?
stabilizes lysosomal membranes to prevent release of proteolytic enzymes
How does cortisol affect capillary permeability and tissue edema?
decreases both
How does cortisol affect synthesis of PGs and leukotrienes?
decreases both by decreasing phospholipase A2
Review anti-inflammatory/immunosuppressant effects of cortisol.
15
Review effects of cortisol on PGs and leukotrienes.
16
How does cortisol affect response to NE and angiotensin 2?
increases responses
What hormone is administered prior to premature births? Explain.
cortisol

increases surfactant production
Review actions of cortisol.
17
How does excess cortisol affect connective tissue?
loss of collagen and connective tissue
Describe 3 ways in which excess cortisol affects bone.
decreases formation and increases resorption

increases osteoclasts

increases PTH and Calcitrol on bone (increased resorption)

*causes osteoporosis
How does excess cortisol affect Ca metabolism?
decreases absorption from GIT

increases excretion by kidneys

*negative Ca balance
Name 4 causes of hypersecretion of cortisol.
19
What is the difference between Cushing's disease and syndrome?
Cushing's disease refers to increase release of ACTH from pituitary
Describe plasma ACTH and cortisol in Cushing's disease.
increased ACTH

increased cortisol
Describe plasma ACTH and cortisol in Cushing's syndrome.
low ACTH (negative feedback)

increased cortisol
Review manifestations of hypercortisolism.
18
What happens to the HPA axis of someone on chronic steroid therapy?
adrenal cortex atrophies because cortisol suppresses CRH and ACTH
Name 3 causes of primary adrenal insufficiency.
autoimmune

HIV/AIDS

TB
Describe a situation in which secondary adrenal insufficiency results.
sudden withdrawal of glucocorticoids after prolonged therapeutic use
Review clinical features of Addison's disease.
20
Describe blood pressure, [Na] and [K] in Addison's disease.
low bp

hyponatremia

hyperkalemia
Describe ACTH levels in Addison's disease.
high
Addison's disease Rx
replacement therapy with cortisol and a mineralcorticoid
Is cortisol or aldosterone production more affected in secondary adrenal insufficiency?
cortisol

ACTH has less effects on integrity of zona glomerulosa
What is the major androgen secreted by the adrenal cortex?
DHEA
What is the commonest enzyme deficiency causing hyposecretion of adrenal cortex hormones?
21-alpha-hydroxylase deficiency
Explain how low cortisol and low aldosterone can cause salt-losing virilizing congenital adrenal hyperplasia.
22
Salt-losing virilizing congenital adrenal hyperplasia Rx
reduce ACTH levels by giving glucocorticoid; 22