KINE1102- midterm lecture 5
PQRST wave
P-> Atrial depolarization(atria getting ready to contract)
QRS complex-> depolarization of ventricles
T-> Repolarization
Pressures
1) Aortic pressure
2) Atrial pressure
3) Ventricular pressure
phases of the cardiac cycle: phase 1-> Ventricular filling
both atria and ventricles are relaxed
blood returns to heart passively
Pressure atria higher than ventricles
AV valves are open, SLV are closed
Depolarization of atrria, P WAVE
Phase 2-> Atrial systole
Atria triggered to contract
Atrial pressure increases
ventricular pressure increasing (filling of ventricles to get to max volume)
Phase 3 -> isovolumetric contraction
QRS complex: depolarization of ventricles (want to contract)
Av valves close
pressure in ventricles is greater than atria
First heart sound "lub"
short period where the AV and SL valves are closed causing a spike in ventricular pessure
gets to a point where VP is greater than aorta which then SL valves open
phase 4-> Ventricular ejection
SL valves open
release of blood
Towards end phase, T wave is where ventricles repolarize
Phase 5-> Isovolumetric Relaxation
VP becomes less than aorta/PT
SL valves close, AV valves open
"DUB" sound
Short period where AV valve and SL valve closed
Cardiac output
amount of blood pumped by the heart per minute (4.9L/MIN)
FORMULA
CO=SVXHR
Stroke volume formula
SR=EDV-ESV
EDV-> volume of blood at the end of diastole
ESV-> volume of blood left at the end of systole
Regulation of SV and HR
1) PRELOAD: degree of stretch of the cardiac walls of the heart due to the amount of blood in the ventricles
2) CONTRACTILITY: force of contraction
3) ADTERLOAD: pressure in arteries the ventricles must overcome to eject blood from the heart
Frank-Starling law
the more strecth, the more reflexive contaction= more blood ejected