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.
Role of aldosterone
Control K+
Role of adrenal gland and K+
- adrenal gland detects how much K+ in ECF
- Increase plasma [K+] is directly detected in adrenal cortex
- Adrenal cortex secretes more aldosterone (also Angiotensin 2 binds to receptors on adrenal cortex, inc release aldosterone
- Aldosterone stimulates principle cells in DCT and collecting duct to secrete more K+ which means reabsorb more Na+ and Cl-
- Which increases [K+] excreted in urine
- 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
Where does renin and angiotensin come from?
REMEMBER angiotensin is NOT aldosterone. Aldosterone = adrenal gland in response to [K+], angiotensin from LIVER
- RENIN released from Juxtaglomerulat cells (in AA) in response to decreased GFR
- Angiotensinogen manufactured in LIVER, released in blood
What is the relationship between renin and angiotensin?
- Renin in blood stream converts angiotensinogen to angeiotensin 1 in plasma, once in lungs, enzyme in lungs convert to Angiotensin 2!
- Sooooo lot of renin means lots of Ag2
Decrease blood volume long term adn RAAS
- Significant drop in BP causes activation RAAS pathway (renin angiotensin aldosterone system)
- Renin binds with Angiotensin in blood = = Ag 1 = lungs + enzyme = Ag2
- Ag2 binds to receptors on adrenal gland= inc secretion ALDOSTERONE
- Aldosterone stimulates principle cells in DCT and collecting duct to secrete more K+(into urine) which means reabsorb more Na+ and Cl-
- more Na+ and Cl- = more water reabsorbed = inc blood volume, therefore venous return and SV
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
- arteriole vasoconstrict
- adrenal cortex secretes aldosterone
- Hypothalamus ADH secretion adn inc thirst
- medulla oblongate reflexes to inc blood pressure
What are angiotensin 2’s effects on GFR?
- overall decreases GFR as decreases blood flow in AA (vasoconstrict Arterioles)
- 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!
