RAAS

Question 1

What does the adrenal gland secrete?

Answer 1

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

Question 2

Role of aldosterone

Answer 2

Control K+

Question 3

Role of adrenal gland and K+

Answer 3

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

Question 4

Where does renin and angiotensin come from?

Answer 4

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

Question 5

What is the relationship between renin and angiotensin?

Answer 5

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

Question 6

Decrease blood volume long term adn RAAS

Answer 6

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-
5. more Na+ and Cl- = more water reabsorbed = inc blood volume, therefore venous return and SV

Question 7

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

Answer 7

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

Question 8

What are angiotensin 2’s effects on GFR?

Answer 8

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!