Blood Pressure

Seite 1

SV = EDV -ESV

SV- stroke volume- amount of blood ejected from the ventricle during a contraction

EDV- The amount of blood volume left after relaxation and filling up of the ventricle

ESV- the amount of blood of blood after contraction and emptying of the ventricle

SV

Stroke volume - the amount of blood ejected from the ventricle during a contraction is affected by

Preload= degree in which the ventricular muscle is stretched, the more blood returning to the heart the greater the stretch of ventricular walls

Contractility= contractile strength independent of stretch

Afterload= is the back pressure of arterial blood that must overcome for ventricles to contract

Frank Starling Law= The greater the length of cardiac muscles the stronger the force of contraction The greater the force the greater the STROKE VOLUME.

Cardiac Output

CO= HR x SV

cardiac output= heart rate x stroke volume

What is blood pressure

Systolic pressure is the highest pressure and is measured when the left ventricle is contracting and expelling blood into the aorta (~120 mmHg)

Diastolic pressure is the lowest pressure and is measured when the left ventricle is relaxing and blood is flowing into the peripheral blood vessels (~80 mmHg)

120/80

How to measure pulse pressure: systolic - diastolic pressure

What determines what your blood pressure is:

Cardiac Output - HR x SV

peripheral resistance- Vasoconstriction and/or increased length increases blood pressure, vasodilation lowers blood pressure.

blood volume- An increase in blood volume will increase blood pressure and a decrease in blood volume will decrease blood pressure

blood viscosity - thick blood is harder to pump- higher pressure is needed