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Flashcards in RAAS Deck (8)
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1

What does the adrenal gland secrete?

Produces and secretes a WIDE range of hormones including Aldosterone from zona glomerulosa (outside cortex)
Adrenaline and noradrenaline from medulla.

2

Role of aldosterone

Control K+

3

Role of adrenal gland and K+

1. adrenal gland detects how much K+ in ECF
2. Increase plasma [K+] is directly detected in adrenal cortex
3. Adrenal cortex secretes more aldosterone (also Angiotensin 2 binds to receptors on adrenal cortex, inc release aldosterone
4. Aldosterone stimulates principle cells in DCT and collecting duct to secrete more K+ which means reabsorb more Na+ and Cl-
5. Which increases [K+] excreted in urine
6. and reabsorbing more Na+ and Cl- = more water reabsorbed = inc blood volume, therefore venous return and SV

Overall..
• If [K+] in plasma goes UP  adrenal gland empties ALDOSTERONE into blood stream, binds to receptos n principle cells DCT, take more K+ into cell, flows doen conc gradient and into urine

Reabsorb more Na+ and Cl- = inc BV = inc venous return and SV = inc BP

4

Where does renin and angiotensin come from?

REMEMBER angiotensin is NOT aldosterone. Aldosterone = adrenal gland in response to [K+], angiotensin from LIVER

1. RENIN released from Juxtaglomerulat cells (in AA) in response to decreased GFR
2. 1. Angiotensinogen manufactured in LIVER, released in blood

5

What is the relationship between renin and angiotensin?

2. Renin in blood stream converts angiotensinogen to angeiotensin 1 in plasma, once in lungs, enzyme in lungs convert to Angiotensin 2!
3. Sooooo lot of renin means lots of Ag2

6

Decrease blood volume long term adn RAAS

1. Significant drop in BP causes activation RAAS pathway (renin angiotensin aldosterone system)
2. Renin binds with Angiotensin in blood = = Ag 1 = lungs + enzyme = Ag2
3. Ag2 binds to receptors on adrenal gland= inc secretion ALDOSTERONE
4. Aldosterone stimulates principle cells in DCT and collecting duct to secrete more K+(into urine) which means reabsorb more Na+ and Cl-
6. more Na+ and Cl- = more water reabsorbed = inc blood volume, therefore venous return and SV

7

Other than binding to adrenal gland to release more Aldosterone, what other systemic effects does angiotensin 2 have on the body?

Effects are to increase BP
1. arteriole vasoconstrict
2. adrenal cortex secretes aldosterone
3. Hypothalamus ADH secretion adn inc thirst
4. medulla oblongate reflexes to inc blood pressure

8

What are angiotensin 2's effects on GFR?

1. overall decreases GFR as decreases blood flow in AA (vasoconstrict Arterioles)
2. soooo there is a sharp drop in renal blood flow BUT filtration is relatively maintained as HSP in glomerular capillaries is preserved as generalised VASOCONSTRICTION has a relatively MORE effects on efferent than AFFERENT arterioles!