Blood Pressure

Raises VR and BP

• Increased blood volume (increase of ADH/kidney failure)

• Increased blood viscosity (polycythemia)

• Decreased distensibility (atherosclerosis)

• Decreased vessel diameter (constriction due to stress)

• Increased vessel length (weight gain)

Baroreceptor Location

Aortic arch and carotid sinus

Baroreceptors

Sensitive to the amount of pressure on the vessel wall; activated by stretch of vessel, relaying impulses to the cardiovascular center (more stretch, the more impulses are sent)

Decreased BP

Less baroreceptor action potential frequency = inhibits parasympathetic system; activate the sympathetic nervous system to increase vasoconstriction, contractility, and HR = increased VR, SV, and venous return

Increased BP

More baroreceptor action potential frequency = activate the parasympathetic nervous system and inhibits sympathetic nervous system to allow vessels to dilate = lessened venous return, SV, and contractility

Chemoreceptor Activation

1.) Hypoxemia (↓ O₂)
2.) Hypercapnia (↑ CO₂) 
3) Acidosis (↑ H⁺), decrease in pH

CVC

Where chemoreceptors send signals

NE/E

Released by adrenal medulla; ↑ BP; increasing CO by raising HR and increasing contractility; also stimulates vasoconstriction

ADH

Released by posterior pituitary; ↑ BP by increasing vasoconstriction as kidneys conserve water and decrease urine output

Renin/Angiotensin/Aldosterone

Released by kidneys/outer adrenal cortex; stimulates vasoconstriction and sodium reabsorption in the kidneys, thus ↑ BP

ANP/ANH

Released by atria; stimulates kidneys to increase urine output: causes vasodilation and the excretion of water leading to a decrease in BP