9.30.13 kin 272 class notes- Preloado Prefilling atria, atrial ejecto If preload decreases… it is difficult to overcome afterload. Not going toeject as much- Afterloado Resistance to ventricular emptyingo Resistence to overcome to ejecto If afterload decreases? Easier to eject- End diastolic volumeo Volume in ventricle at the end of rest (just before contraction)- End systolic volumeo Volume in ventricle at the end of contractiono ESV + SV = EDV- Ejection fraction (definition below)- Heart rate – BPM (beats per minute)- Stroke volume o – volume/beat- CO = HR * SV o = volume/min- Factors affected by how much you start with/end with- Pulse pressureo = sys bp – dias. bpo estimate of what stroke volume would beo in the arterieso contracting vs. resting/relaxingo 120-80 = 40- Diastoleo Rest (not contracting)- Systoleo contraction- what mechanically happens in the ventricle?- HR = 60 bpm… o How much stroke volume?- Ejection fraction:o % volume pushed out per beato EF = 75 % = 300 came out/400 total started with o 25% stayed in a little high standard/healthy/normal is around 60 %- cardiac outputo output per minuteo 4-6 L /min @ resto values based on the needs of the tissueso can go up to 30 liters per min!o whats going to increase? Heart rate (one of the first things)o Stroke volume (slightly)o Moderate increase in HR up to 160o Preload returning faster!o Filling faster up to a certain point- Venous return faster- prefilling is a little more (tiny bit)- Afterload is going to…- Increase EF @rest 60%, @exercise 90%- Aortao 1st layer: Endothelial cells Simple cuboidalo 2nd layer: connective tissue, elastic tissueso outside, 3rd layer: dense
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