1. Excretory System
Blood Pressure
Hormones

2. Blood Pressure Regulation- Background info
Water will go where there are high concentrations of Salt
Increase in water = increase in volume
Increase in volume = increase in pressure

3. Blood Pressure regulation
1) If Low Blood Pressure (BP)
Juxtaglomerular Apparatus secretes renin
Renin is an enzyme that impacts aldosterone release

4. 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

5. 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

6. 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

7. 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

9. 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