Question

In a sentence or two each, explain how each of the structural adaptations would improve stroke volume. Hint: stroke volume is related to EDV (filling), ESV (contractility), AND Frank-Starling mechanism. Also keep in mind the concept of pre-load and after-load. Therefore, explain how the structure could affect some or all of those components.

Increased LV internal diameter

Increased LV mass

Increased LV wall-thickness

Increased Atrial thickness

Increased aortic compliance

Increased plasma volume

Increased muscle capillary volume

Answer 1

Increased LV internal diameter > increased diastolic volume > increased initial length of muscle fiber > increased contractility > increased SV

Increased LV mass > increased contractility > increased SV.

Increased LV thickness > increased contractility > increased SV.

Increased atrial thickness > increased atrial contractility > increased diastolic filling > increased initial length of muscle fiber > increased contraction > increased SV.

Increased aoric compliance > less resistance to outflowing blood > increased SV.

Increased plasma volume > increased filling > increased initial length of fiber > increased contractility > increased SV.

Increased muscle capillary volume itself means increased SV.

Note: The Frank-Starling Law states that the stroke volume of the left ventricle will increase as the left ventricular volume increases due to the myocyte stretch causing a more forceful systolic contraction.