Blood Pressure Regulation- Blood Pressure Regulation- Background infoBackground info

►Water will go where there are high Water will go where there are high concentrations of Saltconcentrations of Salt

► Increase in water = increase in volumeIncrease in water = increase in volume► Increase in volume = increase in Increase in volume = increase in

pressurepressure

Blood Pressure regulationBlood Pressure regulation

1) If Low Blood Pressure (BP)1) If Low Blood Pressure (BP)► Juxtaglomerular Apparatus secretes reninJuxtaglomerular Apparatus secretes renin

Blood Pressure regulationBlood Pressure regulation

1) If Low Blood Pressure (BP)1) If Low Blood Pressure (BP) AldosteroneAldosterone

► Renin is an enzyme that changes Renin is an enzyme that changes angiotensinogen into Angiotensin Iangiotensinogen into Angiotensin I

► Angiotensin I is then converted into Angiotensin I is then converted into Angiotensin IIAngiotensin II

► Angiotensin II stimulates the adrenal Angiotensin II stimulates the adrenal cortex to release aldosteronecortex to release aldosterone

Blood Pressure regulationBlood Pressure regulation

1) If Low Blood Pressure (BP)1) If Low Blood Pressure (BP)► Aldosterone promotes the excretion of Aldosterone promotes the excretion of

KK++ and the reabsorption of Na and the reabsorption of Na++

► The reabsorption of NaThe reabsorption of Na++ is followed by is followed by the reabsorption of H2Othe reabsorption of H2O

► Blood volume and blood pressure Blood volume and blood pressure increaseincrease

16.3 Regulatory Functions 16.3 Regulatory Functions of the Kidneysof the Kidneys

2) If High Blood Pressure (BP)2) If High Blood Pressure (BP)

Atrial naturietic hormone (ANH)Atrial naturietic hormone (ANH)► Another hormone regulating sodiumAnother hormone regulating sodium► Secreted by right atrium of heart in response to Secreted by right atrium of heart in response to

stretchingstretching► Indicates increased blood volumeIndicates increased blood volume► Inhibits renin secretion by juxtaglomerular apparatusInhibits renin secretion by juxtaglomerular apparatus► Inhibits aldosterone releaseInhibits aldosterone release► Promotes sodium excretion - natriuresisPromotes sodium excretion - natriuresis

Juxtaglomerular ApparatusJuxtaglomerular Apparatus

16.3 Regulatory Functions 16.3 Regulatory Functions of the Kidneysof the Kidneys

-3) Permeability of collecting duct is under -3) Permeability of collecting duct is under hormonal controlhormonal control

► Antidiuretic hormone (ADH) Antidiuretic hormone (ADH) `is released by the posterior pituitary gland (made by the `is released by the posterior pituitary gland (made by the

hypothalamus) to regulate BPhypothalamus) to regulate BP In the presence of ADH, the collecting duct become more In the presence of ADH, the collecting duct become more

permeable to waterpermeable to water Water will leave the kidney and enter blood (Water will leave the kidney and enter blood (↑BP) ↑BP) and a and a

concentrated urine is producedconcentrated urine is produced

In the absence of ADH, the collecting duct become less In the absence of ADH, the collecting duct become less permeable to waterpermeable to water

Water will not leave the kidney and a dilute urine is Water will not leave the kidney and a dilute urine is producedproduced

16.3 Regulatory Functions 16.3 Regulatory Functions of the Kidneysof the Kidneys

► DiureticsDiuretics Increase flow of urineIncrease flow of urine AlcoholAlcohol

► Shuts off ADH (antidiuretic hormone) causing larger urine Shuts off ADH (antidiuretic hormone) causing larger urine volumesvolumes

► Dehydration causes hangoverDehydration causes hangover CaffeineCaffeine

► Increases glomerular filtration rateIncreases glomerular filtration rate► Decreases tubular reabsorption of sodiumDecreases tubular reabsorption of sodium

Diuretic drugsDiuretic drugs► Many inhibit active transport of sodium at loop of the nephronMany inhibit active transport of sodium at loop of the nephron

SummarySummary

►Know the background infoKnow the background info►Know the mechanisms of the 3 Know the mechanisms of the 3

hormones that regulate blood pressure hormones that regulate blood pressure