| Cardiac output =.... | Stroke volume * heart rate |
| Define stroke volume | stroke volume is the difference between the
end diastolic volume
end systolic volume |
| What is the ventricular compliance curve? | relationship between venous pressure and ventricular volume. The higher the venous pressure the more the heart fills in diastole. |
| What is preload? | Tension on the ventricular wall at the end of diastole (just before contraction) The more stretched the myocytes the greater contraction which can occur. |
| Starlings Law | The more the heart fills, the harder it contracts. The harder it contracts the bigger the stroke volume. (Rise in venous pressure automatically leads to rise in stroke volume) |
| What is afterload? | The tension the ventricular wall during contraction, (it is the resistance that must be overcome for the ventricle to eject it's content). It is approximated by systolic ventricular (or arterial) pressure. |
| What happens to SV when venous pressure rises? | SV rises |
| What happens to SV when arterial pressure falls? | SV rises |
| Where are the baroreceptors which control the autonomic outflow? | Carotid sinus |
| How to falls in arterial pressure lead to increased heart rate? | Increasing sympathetic activity (increase contractility)
Reducing parasympathetic activity |
| What does rise in venous pressure cause | increase stroke volume (Starlings Law)
increase heart rate (reduced parasympathetic activity) |
