cardiac physiology Q5

increase in blood returning to heart increases EDV which causes extra stretching which causes increase in the next contraction.

increased stretch of ventricles result in overlap of actin and myosin filaments>more cross bridges > increases stretch increases the sensitivity of contractile proteins to Ca++> intra ca++ required to generate 50% max tension is now lower when muscle fibre is stretched.

through sympathetics and parasympathetics divisions of ANS in medulla oblongata.

<p>chronotrophic effects.</p> Signup and view all the answers

<p>increase in heart rate (sympathetic); norepinephrine is released from sympatshtcis nerve fibres&gt; activate Beta1 receptors in the SA node&gt; an increase in funny channels (Na+)&gt; increase the rate of phase 4 depolrization and intra Ca++ channels&gt;more action potential&gt;increase heart rate.</p> Signup and view all the answers

<p>a decrease in heart rate- acetylcholine is released from parasympathetic nerve fibres&gt;activate muscarinic receptors in the SA node</p> Signup and view all the answers

<p>BP= CO<em>SVR CO (cardiac output)=SV</em>HR. SVR (systemic vascular resistance) the resistance the blood encounters as it moves through the (atrial system).</p> Signup and view all the answers

<p>by SV (stroke volume) being ejected by the heart and the ability of aorta to stretch to accommodate SV.</p> Signup and view all the answers

<p>the energy stored in the elasticity of fibres that are stretched during systole.</p> Signup and view all the answers

<p>because of their abundant (elastic tissue)</p> Signup and view all the answers