BIO 365S Lecture Notes - Lecture 30: Angiotensin, Osmotic Concentration, Aldosterone
HOMEOSTATIC RESPONSES TO SALT INGESTION
Increases osmolarity as trigger due to salt ingestion = big trigger for vasopressin release =
increase water reabsorption, so kidney conserve water. Osmolarity increase also goes to cortex
to make you feel thirsty to drink more water = increase ECF volume, which affects blood
pressure to increase (goes hand in hand), and now kidneys can excrete salt and water, and
cardiovascular system can respond.
In integrated systems, every system that can do something will do something to maintain
homeostasis. Have more than one system respond to sodium increase.
Aldosterone:
1. released by adrenal cortex
2. Target P cells
3. Active reabsorb Na+ (secret K+)
Steroid hormone. Can directly go into the cell, has intracellular receptor, when activated, works
like a transcription receptor to move into nucleus, and output = more sodium channels for
more sodium reabsorption, and also puts more Na/K ATPase on membrane to pump more Na+
out and K+ in (Na+ absorbed, K+ secreted).
The renin-angiotensin system (RAS)
Aldosterone regulates BP by regulating Na+ reabsorption
Rei, graular ells JG ells sese stress, releases rei. Rei’s futio is to tur horoe
called angiotensinogen (little function, not important) into ANG I (also not important), goes to
blood which contains ACE to turn ANG I into ANG II (very powerful hormone, is a
vasoconstrictor so blood flow decreases and blood pressure increases; directly goes to CDCC
and make sympathetic output increase, which increases cardiovascular response = increase
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Document Summary
Increases osmolarity as trigger due to salt ingestion = big trigger for vasopressin release = increase water reabsorption, so kidney conserve water. In integrated systems, every system that can do something will do something to maintain homeostasis. Have more than one system respond to sodium increase. Aldosterone: released by adrenal cortex, target p cells, active reabsorb na+ (secret k+) Re(cid:374)i(cid:374), gra(cid:374)ular (cid:272)ells (cid:894)jg (cid:272)ells(cid:895) se(cid:374)se stress, releases re(cid:374)i(cid:374). Produced by myocardial cells in the atrium in the heart. Bv increase triggers a lot of pathways, and goal is to decrease the total body water volume and blood volume. Hypothalamus decreases vasopressin = less water coming back. Kidney = increase gfr by dilating afferent arterioles, more plasma being filtered into lumen, and more water being excreted. Also decrease renin release, and decrease aldosterone (ras path(cid:449)ay = i(cid:374)(cid:272)reases bp, so do(cid:374)"t (cid:449)a(cid:374)t to (cid:373)ess up the fu(cid:374)(cid:272)tio(cid:374) of avp(cid:895). Drinking water: only way to replace lost water.
