1. 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

2. Blood Pressure regulation  1) If Low Blood Pressure (BP) ► Juxtaglomerular Apparatus secretes renin

3. Blood Pressure regulation  1) If Low Blood Pressure (BP) Aldosterone 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

4. 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

5. 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

6. Juxtaglomerular Apparatus

7. 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

8. 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

9. Summary ► Know the background info ► Know the mechanisms of the 3 hormones that regulate blood pressure