AG

25. Regulation of Blood Pressure and Osmolarity

Low Blood Pressure

High Blood Pressure

Low Blood Osmolarity

High Blood Osmolarity

Low GFR

High GFR

Where detected?

Stretch receptors in aorta and carotid artery AND Macula densa in DCT

Stretch receptors in aorta and carotid artery

Osmoreceptors in hypothalamus

Osmoreceptors in hypothalamus

Action

Hypothalamus to release ADH AND release of renin à angiotensin + aldosterone

Hypothalamus to inhibit ADH release

Inhibit ADH release

Stimulate ADH release

Kidney effects

↑ GFR (vasoconstriction by angiotensin)

↑ Na+ absorption (aldosterone)

↓ H2O permeability in DCT and collecting duct

↑ urine volume

↓ H2O permeability in DCT and collecting duct

↑ urine volume

↑ H2O permeability in DCT and collecting duct

↓ urine volume

Blood effects

↑ BP

Vasoconstriction

↓ BP

↑ blood osmolarity

↓ blood osmolarity

Thirst

Stretch receptors- how they work

  1. baroreceptors

    1. stretch receptors in carotid artery - aorta

REMEMBER

  1. renin released in the kidneys and dumped into the blood system (afferent arteriole)

  2. starts cascade of converting angiotensinogen into angiotensin