The events of the cardiac cycle Flashcards
How does blood enter the right atrium
Superior and inferior vena cava
Why does blood flow straight through from the vena cava to the right atrium
Nothing separating them ie no valves
What valve separates the right atrium and right ventricle
Tricuspid valves (AV valves)
What valve separates the right ventricle from the lungs
Pulmonary valve
What valve separates the left atrium from the left ventricle
AV valves (bicuspid/mitral)
What valve separates the left ventricle from the aorta
Aortic valve
What is the significance of the volume of blood pumped from the RHS and LHS of heart
-What is the exact volume
Same
-5 Litres/ minute
or
70ml/beat
What is the pressure generated from LHS like compared to the RHS and why
Pressure generated is 4x greater in LHS because the LHS needs to overcome the pre-existing pressure in the system
What are systole and diastole
Systole- contraction
Diastole-relaxation of ventricle
What are the relative pressures like in atrial systole
Rise in atrial pressure and same relative rise in ventricular pressure however atrial pressure is just a bit above.
Aortic pressure falls because blood is not being flowed into it
Relative pressures as the wave of excitation goes to the ventricles
Aortic pressure still falls because blood still not flowing to it
Relative pressures and what happens during isovolumetric ventricular contraction
- Increase in ventricular pressure closes AV valves
- VEntricular pressure is less than aortic pressure so the aortic valve is still closed
Relative pressures and actions in ventricular ejection
-Ventricular pressure exceeds aortic pressure and therefore the aprtic valve opens and blood is ejected
What happens in isovolumetric ventricular relaxation
- VEntricular pressure less than aortic pressure so aortic valves close
- Ventricular pressure is still greater than atrial pressure therefore the AV valves are still shut
- Pressure falls but there is no filling
What happens in ventricular filling
Ventricular pressure is less than atrial pressure so AV valves open and blood enters the ventricles
What is Ejection Fraction
The volume of blood emptied by the heart (because heart does not empty all of its content as it would require a lot of energy to refill the whole heart from scratch)
What do pulsations in the internal jugular vein reflect
Right atrial pressure changes as there is no valve separating the vena cava and the right atrium
What are the two sounds you can hear with a stethoscope
First- Closure of the AV valves as the left ventricular pressure exceeds atrial pressure
Second- Closure of the aortic valve/pulmonary valve
What is a raised jugular venous pulse an indication of
Right hand side heart failure because the right hand side can’t pump effectively which is reflected in the venous side
When does the aortic valve open
During systole
When does the aortic valve close
Start of diastole
When does the mitral valve open
During diastole
When does the mitral valve close
Start of systole
