Frank-starling Principle

Question 1

What is the frank-starling principle?

Answer 1

Effectively: The heart muscles need something to push back against in order to contract effectively - a strong launchpad for a good squeeze and a big jet of blood.

1. The launchpad = end diastolic volume - LVEDV (potential blood to be propelled out)
2. LVEDV = Left ventricular end diastolic pressure - LVEDP
   This volume exerts a pressure against the ventricle which the ventricle can push against! (Without blood in the ventricle it will just wildly flail)
3. How much of this LVEDV is pumped out is the stroke volume (AKA ejection fraction)
4. How well the heart can push back against the LVEDV is the heart’s contractility (the rocket).
   Contractility is a product of the heart being a single unit that works synchronously amongst its various parts.
   Things that make it decrease: Damage, lesions, MI, ischemia, arrhythmias, dilation, thickening/thinning of walls.
5. So we have two pieces here;
   LVEDV (preload/launchpad) launchpad and the contractility (structural and functional integrity/rocket)
   - As LVEDV or contractility increases we see an increase in the amount of blood ejected (stroke volume)
   - The relationship between the two is the frank starling principle.