Blood Pressure RegulationBackground info
► Water
will go where there are high
concentrations of Salt
► Increase in water = increase in volume
► Increase in volume = increase in pressure
Blood Pressure regulation
 1) If Low Blood Pressure (BP)
► Juxtaglomerular
Apparatus secretes renin
Blood Pressure regulation
 1) If Low Blood Pressure (BP)
Aldosterone
► Renin
is an enzyme that changes
angiotensinogen into Angiotensin I
► Angiotensin I is then converted into
Angiotensin II
► Angiotensin II stimulates the adrenal cortex
to release aldosterone
Blood Pressure regulation
 1) If Low Blood Pressure (BP)
► Aldosterone
promotes the excretion of K+
and the reabsorption of Na+
► The reabsorption of Na+ is followed by the
reabsorption of H2O
► Blood volume and blood pressure increase
16.3 Regulatory Functions
of the Kidneys
 2) If High Blood Pressure (BP)
Atrial naturietic hormone (ANH)
► Another hormone regulating sodium
► Secreted by right atrium of heart in response to stretching
► Indicates increased blood volume
► Inhibits renin secretion by juxtaglomerular apparatus
► Inhibits aldosterone release
► Promotes sodium excretion - natriuresis
Juxtaglomerular Apparatus
16.3 Regulatory Functions
of the Kidneys
-3) Permeability of collecting duct is under hormonal
control
► Antidiuretic
hormone (ADH)
 `is released by the posterior pituitary gland (made by the
hypothalamus) to regulate BP
 In the presence of ADH, the collecting duct become more
permeable to water
 Water will leave the kidney and enter blood (↑BP) and a
concentrated urine is produced
 In the absence of ADH, the collecting duct become less permeable
to water
 Water will not leave the kidney and a dilute urine is produced
16.3 Regulatory Functions
of the Kidneys
►
Diuretics
 Increase flow of urine
 Alcohol
► Shuts
off ADH (antidiuretic hormone) causing larger urine volumes
► Dehydration causes hangover
 Caffeine
► Increases
glomerular filtration rate
► Decreases tubular reabsorption of sodium
 Diuretic drugs
► Many
inhibit active transport of sodium at loop of the nephron
Summary
► Know
the background info
► Know the mechanisms of the 3 hormones
that regulate blood pressure