HK 3810 Midterm: PHYS II part I

• School: University of Guelph
• Department: Human Kinetics
• Course: HK 3810
• Professor: Dr. Murrant

Document Summary

How do nodal cells generate ap: slow na+ leak in causes a slow flux, massive conc grad spikes causes rapid depol moving towards its eion; stops at +20mv. How can sns change hr: sns release ne increase perm of nodal cells to na+ increase sodium leak rate. Reach threshold faster increase spont depol rate increase hr. How can pns change hr: pns opens ach dependent k+ channels hyperpol increase time to reach threshold decrease ap/min decreased hr. Valves: all valves are passive; opens via pressure gradients, leaflets of valves close to prevent backflow, capillary muscles and corda tendina prevent valve leaflets eversion. Left ventricle p/v relationship: diastole (ventricle relaxed) ventricle is filling, atrial contraction; small increase of vol and p, ap moves to av, his, purkinje onto ventricular myocytes, systole (ventricle contracted) Increase in vent pr; closes mitral valve (prevents backflow); aortic valve already closed. End diastolic volume (edv) ma(cid:454) a(cid:373)ou(cid:374)t of (cid:271)lood a(cid:448)aila(cid:271)le to pu(cid:373)p (cid:894)do(cid:374)"t pu(cid:373)p out all(cid:895)