PHYS30001 Lecture 16: 16 Hormonal control of heart function A
Document Summary
Predominantly produced in adrenal medulla a modified sympathetic ganglion. Modified postganglionic neurons lack axons use blood instead! Adrenaline and noradrenaline actions slightly different (receptor access and affinity) Sympathetic effects on heart & vessels: transmitters vs hormones. 1: more mediated by adrenaline; 2: increases blood supply of heart for increased contraction. 1: most systemic vessels constrict, e. g. git (driven more by nad neural input) inotropic agent : affects contractility (positive increases and negative decreases) chronotropic agent : affects heart rate (positive increases and negative decreases) Adrenaline: positive inotropic & chronotropic action, coronary vasodilation and systemic constriction. Ca current (through l & t type channels in sarcolemma) Sr ca atpase (reduce phospholamban inhibition): faster reuptake. Sr ca release channel (increases open probability) Contraction (tn-i effect): increased sensitivity of myofilaments to calcium. Adrenaline binds 1 activates g s (on the gs g-protein) adenyl cyclase camp . Larger and faster ca transients, more rapid relaxation.
