RAAS Flashcards

1
Q

What stimulates renin release?

A
  1. Decreased tubular flow sensed by macula densa.
  2. Low afferent arteriolar pressure. (Internal renal baroreceptors)
  3. Sympathetic nervous system stimulation (B1)
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2
Q

What is the rate-determining step in the RAAS?

A

The renin mediated proteolysis of angiotensinogen determines rate.

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3
Q

Where does angiotensin II target/ stimulate?

A
  1. Smooth muscle in vasculature- vein/vaso constrict. Increase SVR.
  2. Adrenal gland - secrete aldosterone
  3. Pituitary- ADH release (posterior lobe pituitary) and sympathetic nervous system
  4. Kidneys- vasoconstriction both afferent + efferent arteriolar, but maintain GFR. Increase SVR of kidneys.
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4
Q

Where does angiotensingen and renin originate?

A

Angiotensinogen found in the liver and released to circulate blood.

Renin is secreted by granular cells, juxtaglomerular apparatus in the kidney.

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5
Q

Where can the macula densa be located?

A

At the junction of DCT and thick ascending limb of Loop of Henle.

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6
Q

What is aldosterone and where is it produced?

A

It is a steroid hormone, produced in the zona glomerulosa in the adrenal gland.

It accounts for 95% of the bodies mineralocorticoid activity.

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7
Q

What are the layers of the adrenal gland and what do they produce?

A

Layers: GFR
Zona glomerulosa - aldosterone
Zona fasiculata - cortisol
Zona reticularis - testosterone precursors

Hormones: ACTH

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8
Q

What is the effect of Aldosterone?

A

Promotes Na and water reabsorbtion.

K+ and H+ excretion.

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9
Q

What is the main trigger for renin release?

A

Decreased renal blood flow

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10
Q

What directly and indirectly stimulates aldosterone secretion?

A

Directly:

  1. Hyperkalaemia
  2. Acidosis
  3. ACTH

Indirectly:
1. Renin via RAAS

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