Cardiac Function and its Control Flashcards
What does blood pressure depend on?
The compliance in the vessel wall and the active tension in the vessel wall
Which is more important in diastole?
Compliance
Which is more important in systole?
Active tension
What is compliance?
The ability of a chamber to accept increased volume
Is the pericardium important in compliance?
In a healthy heart no, but can be important if it fibroses and is stiff or if there is pericardial effusion
Which ventricle is less compliant?
The left ventricle - because the wall is thicker
Which ventricle can generate more force?
The left ventricle - because it has to pump against systemic pressure
What is the left ventricular end diastolic volume?
75mL
What is the left ventricular stroke volume?
100mL
What is the left ventricular end diastolic pressure?
15mmHg
What is the left ventricular early diastolic pressure?
5mmHg
What causes an increase in stroke volume?
Increase in ventricular contractility and increase in end diastolic volume
Does an increased heart rate increase stroke volume?
No
How is contractility increased?
With sympathetic nerve activation, caffeine, adrenaline, increased intracellular calcium
What valves are open in diastole?
The AV valves
What valves are open in systole?
The semilunar valves
What valves are open in isovolumetric contraction?
None
What causes the first heart sound?
Closing of the AV valves
What causes the second heart sound?
Closing of the semilunar valves
What is after load?
The pressure after the ventricles
When do you get high after load?
In high blood pressure and aortic valve stensois
What is preload?
The volume which goes into the ventricles
When do you get increased preload?
With increased venous return
