LO10: Define blood pressure and describe the factors that influence it.

What is blood pressure?

The force blood exerts on the walls of arteries as the heart pumps it around the body.

How does cardiac output (CO) affect blood pressure?

Increased CO raises blood pressure; decreased CO lowers blood pressure.

What is the formula for cardiac output?

CO = Heart Rate (HR) × Stroke Volume (SV).

What causes cardiac output to increase?

Increased heart rate (e.g., exercise, stress) or increased stroke volume (e.g., more venous return, stronger heart contractions).

What causes cardiac output to decrease?

Decreased heart rate (e.g., rest, parasympathetic activity) or decreased stroke volume (e.g., blood loss, weak heart).

How does peripheral resistance affect blood pressure?

Increased peripheral resistance raises blood pressure; decreased peripheral resistance lowers blood pressure.

What physiological mechanisms increase peripheral resistance?

Vasoconstriction—narrowing of arterioles, caused by sympathetic nervous system stimulation or hormones like angiotensin II.

What physiological mechanisms decrease peripheral resistance?

Vasodilation—widening of arterioles, caused by parasympathetic activity, nitric oxide release, or certain hormones.