15 Cardiac cycle Flashcards
Under sympathetic activity, there is a ______________ in which more Ca2+ will be released.
_____________ phosphorylation facilitates it.
Calcium-induced Calcium release.
RyR (Ryanodine receptor)
Ca2+ uptake up by ____________ is needed for relaxation.
Under sympathetic stimulation what happens?
SERCA
(Smooth ER Ca2+ ATPase)
phosphorylated PLB suppresses the inhibitory effect of PLB > more effective Ca2+ uptake, faster relaxation
How is Ca2+ extruded into extracellular space?
Na+/Ca2+ exchanger (NCX)
or
plasma membrane Ca2+ ATPase
What are the 5 events of a heart beat?
- Atrial systole
- Isovolumetric contraction
- Ventricular ejection
- Isovolumetric ventricular relaxation
- Ventricular diastole
During atrial systole, mitral valve _________. Why?
closes when ventricular pressure exceeds atrial pressure
> ventricular filling stops
Isovolumetric ventricular contraction is a period of ventricular contraction when no blood is ejected. Why will this happen?
What are the states of the valves?
Ventricular pressure is lower than aortic pressure
All closed
When is the 1st heart sound audible?
Mitral valve / Atrioventricular valves close during isovolumetric ventricular contraction.
When is the 2nd heart sound audible?
Aortic valves close during isovolumetric ventricular relaxation.
When does isovolumetric ventricular relaxation occur?
When ventricular pressure drops
_________ is a result of aortic valve closing, creating
turbulence and transient increase in aortic pressure.
Dicrotic notch
Does the mitral valve open during isovolumetric ventricular relaxation?
No.
Ventricular diastole occurs when ventricles are fully relaxed.
_______ also means slowed ventricular filling.
Diastasis
The pressure changes in ______ and ______ is similar.
Pulmonary artery pressure and right ventricular pressure
What is the equation to SV?
What is the typical volume?
SV = EDV - ESV
70 ml = 135-65 ml
Ejection fraction describes the effectiveness of ventricular ejection. How can it be calculated?
What is the normal number?
EF = stroke volume/ EDV
0.55
normally >0.5
What does the Frank-Starling relationship tell us?
Stroke volume increases as cardiac filling increases
What is the autonomic effect on stroke volume? (Sym or para or both? What receptors are stimulated?)
Sympathetic only
Ach stimulates M2 receptors in atria
and B1 receptors increases ventricular contractility
- stroke volume increases due to increased contractile force even EDV is the same
In pressure volume loop, what are the x and y axises respectively?
X: left ventricular volume
Y: Left ventricular pressure
What does the length of a horizontal line drawn from 4 to 1 means?
SV
when 4> 1 from left to right, what happens?
What is the states of mitral valve?
Ventricular filling
4: opens
1: closes; EDV
When 1>2 in P-V loop from down to upwards, what happens?
Isovolumetric contraction
When 2>3 in P-V loop from right to left, what happens?What is the states of aortic valve?
Ventricular ejection
2: opens
3: closes; ESV
What does the point 1 in a P-V loop indicates?
EDV
What does the point 3 on a P-V loop indicates?
ESV
When 3>4 in a P-V loop, from up to downwards, what happens?
Isovolumetric relaxation
What does preload mean?
EDV
What is indicative of afterload?
Aortic pressure / MAP
In hypertension patients, how will the P-V loop change?
- decreased SV (increase afterload= need more pressure to push the same amount of blood)
> narrower loop
- higher point of 2 (needs higher pressure)
- higher and earlier point of 3, as aortic pressure is even higher, it shuts the valve
