aka BSCC Physiology 013
Basic Science in Clinical Context Examination: 2 minutes long in 2 parts.
- Exam candidate answering a question (under exam conditions)
- Professor providing a more detailed explanation (with transcript)
Draw a Frank Starling curve and list the factors that affect contractility of the ventricle
Examinee response: Drawing and explanation in real-time video/audio
Frank Starling Curve
The X axis is ventricular end diastolic volume; and the Y axis is stroke volume
As ventricular end diastolic volume increases, stroke volume also increases.
The dashed lines indicate where maximal contractility has been exceeded and any filling beyond this point causes a reduction on stroke volume.
The curve shifts upwards and to the left as contractility is increased. The main factors that increase contractility are:
- Sympathetic drive
- Post extra-systolic potentiation
- Increase in heart rate (minimal increase)
The curve shifts downwards and to the right as contractility is decreased. The main factors that decrease contractility are:
- Parasympathetic drive
- Intrinsic depression (MI, CHF, cardiomyopathy)
- Drugs (calcium channel blockers, beta blockers, procainamide and barbiturates)
in Clinical Context