Lecture 11 - Regulation of Cardiac Function II

Question 1

SNS innervates?

Answer 1

essentially all of heart: atria, ventricles, SA and AV nodes,

Question 2

PNS innervates?

Answer 2

mainly atria, SA and AV node

Question 3

Sympathetic regulation of cardiac action - rate and rhythm and contractility?

Answer 3

increases heart rate (slow progress into rhythm), reduction of cardiac action potential with acceleration of impulse propagation through AV node, increased ionotropic state of A and V

Question 4

Sympathetic effects on cardiac cycle?

Answer 4

increased: pressure of atrial contract., rate and peak of LV pressure, ejection acceleration, aortic flow (SV); decreased ESV, rapid filling occurs faster to sustain constant ventricular filling despite shortened dia/systole

Question 5

Effects of parasympathic stimulation?

Answer 5

reduced HR, reduced atrial A.P., impulse deceleration through AV node, decreased atrial inotropic state, little decrease in ventricular inotropic state (little PNS innervation)

Question 6

Factors affecting oxygen demand?

Answer 6

basal metabolism, wall force development (pressure over time, geometry - essentially afterload), inotropic state, heart rate

Question 7

Factors affecting oxygen supply?

Answer 7

perfusion pressure (aortic pressure, extravascular compression from contractions), impedance (local regulation)

Question 8

Ways to increase oxygen supply?

Answer 8

increase oxygen concentration, increase oxygen extraction, increase blood flow