PSY 101 Final: Psych 101 lec
Document Summary
Cardiac conduction system (intrinsic control: spontaneous rhythmicity: special heart cells generate and spread electrical signal. Purkinje fibers: electrical signal spreads via gap junctions. Observed in heart transplant patients (no neural innervation: sa node: initiates contraction signal. Pacemaker cells in upper posterior ra wall. Signal spreads from sa node via ra/la to av node. Impulse for a normal heart contraction begins in the. Sa node: av node: delays, relays signal to ventricles. In ra wall near center of heart. Delay allows ra, la to contract before rv, lv. Relays signal to av bundle after delay: av bundle: relays signal to rv, lv. Divides into right and left bundle branches. Sends signal toward apex of heart: purkinje fibers: send signal into rv, lv. Terminal branches of right and left bundle branches. Parasympathetic nervous system (extrinsic control: reaches heart via vagus nerve (cranial nerve x, carries impulses to sa, av nodes. Decreases hr, force of contraction: decreases hr below intrinsic hr.
