Excretory System Blood Pressure Hormones

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

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

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

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

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

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