Cardiac Cycle Flashcards
(43 cards)
Name the two atrioventricular valves and state which side of the heart they are on and number of cusps.
Tricuspid 3 Right
Mitral 2 Left
List the 7 phases of the cardiac cycle
Atrial Contraction Isovolumetric Contraction Rapid Ejection Reduced Ejection Isovolumteric Relaxation Rapid filling Reduced Filling
In a raised or slowed heart rate what changes time in systole, diastole or both?
Diastole
How much of the cardiac cycle systole?
1/3- 0.35s
Which vessels are resistance vessels?
Arterioles
Are veins resistance or capacitance vessels?
Capacitance
Which operates under higher pressure systemic or pulmonary circulation?
Systemic
What is diastole?
Relaxation and filling time for ventricles
What happens to blood in systole?
Ejected from contracting ventricles
Are cardiac action potentials long or short?
Long - 280ms
What is the outflow valve of the right vertical called?
Pulmonary valve
The aortic valve is the ….. valve of the left ……
outflow
ventricle
What causes the opening and closing of valves?
Differential blood pressure on each side.
Closing prevents back flow
Opening allows through flow.
Paillary muscles in the ventricles are connected to the mitral and tricuspid valves by what structure? Why do we need this structure?
Chordae-tendinae
Prevents inversion of valves in systole.
Where are the pace maker cells in a normal functioning heart?
SAN
What is the delay time of an action potential at the AV node?
120ms
Ventricular depolarisation flows in which direction within the myocardium?
Endocardium to epicardium.
What is the direction of ventricular contraction?
Contract from apex up- squeezing blood through aortic and pulmonary valves.
Which 3 stages of the cardiac cycle are in systole?
Isovolumetric contraction
Rapid ejection
Reduced ejection
Phase 1 of the cardiac cycle is atrial contraction - outline events and Wigger diagram features.
A wave - atrial depolarisation
P wave on ECG
Atria contract and ventricular EDV is reached (atria pump in the last 10%)
What phase of the cardiac cycle is started by S1?
What happens in this phase?
Phase 2: Isovolumetric contraction
S1 is the mitral and tricuspid valves shutting (Ventricular pressure now higher than atria)
QRS- ventricular depolarisation
Rapid rise in pressure but no volume change as aortic valve is shut.
C wave denotes a slight atrial pressure increase as the valve shuts
What is S2?
Closure of the pulmonary and aortic valves in isovolumetric relaxation (phase 5)
What happens in rapid ejection?
Phase 3 of the cardiac cycle is rapid ejection and starts with the aortic valve opening.
X descent on atrial pressure as the ventricluar contraction pulls the atrial base down.
Rapid decrease in volume with a rising pressure in the ventricle.
Aortic pressure increases.
While the ventricles contract what happens in the atria?
Atria fill from venous input