Cardiac Cycle

cgeorge's version from 2016-02-26 14:41


Question Answer
Whole cycle duration is800ms
Systole lasts300ms
Diastole lasts500ms
Greatest resistance in which blood vessels?Arterioles
Afterload isWhat u are pushing against
Aortic valve will shut whenPressure in aorta is higher than P in ventricle
Aortic vale will open whenP ventricle > P in aorta
AV valve will close when P in ventricle > P atria
Describe phase 1Patria > P ventricles. Atrium depolarisation. AV valve open. Slight rise in ventricular volume towards end due to slight contraction of atria
What is the P waveAtrium depol
EDV value is120ml
Describe phase 2Isovolumetric contraction. Pventricles > Patria. Ventricles depolarise. AV valve closes
What is the QRS waveVentricle depol
What is the cause of the first heart soundAV Valve shutting in phase 2 (isovolumetric contraction). Volume of blood in ventricle cant change
Function of isovolumetric contraction isTo generate enough ventricular pressure to open aortic/pulmonary valves
Describe phase 3Rapid ejection. Aortic and pulmonary valves open. P ventricle > Paorta. Aortic valve opens
Describe phase 4Reduced ejection.Aortic/pulmonary valve still open. Ventricles repolarise. P in ventricles > P in aorta but aortic valve remains open due to momentum
What is the T waveVentricles repolarising and starting to relax
Describe phase 5Isovolumetric relaxation. All valves closed. Diastole begins when aortic valve shuts
What is the cause of the second heart soundAortic valve shutting.
ESV value is50ml
Function of isovolumetric relaxationNeed pVentrciles < P atrium to open AV valves again and restart the cycle.
Pressure of right ventricle at end of systole - 20mmHg
Pressure of right atrium at end of systole = 4mmHg
Why doesnt ventricle completely empty?You are pushing against resistance