9 November 2009 Cardiovascular Physiology Lab this Week: Human EKGs, Heart Sounds, and Blood Pressure… Wear running shoes, comfortable clothes, bring calculator & textbook. Abstracts due Friday at start of Class.

Cardiac Output = Heart Rate X Stroke Volume CO = HR x SV 5L/min = 72 beat/min x 70 ml/beat

Figure 12.07 Tricuspid Bicuspid =Mitral Problems with valves: ….Stenosis (narrowing) →Heart Murmurs (turbulent flow past a constriction) note: origin of neonatal heat murmurs (foramen ovale) ….Prolapse (eversion) allows backflow (also generates murmurs) Figure 12.07 Bicuspid =Mitral Tricuspid Heart sounds and valve closings Semilunar Valves

SA node cells spontaneously produce AP, do not have stable resting membrane potential, are Pacemaker cells Figure 12.11

Intercalated Discs: mechanical attachments of cardiac myofibers to each other, with gap junctions (electrical synapses) to conduct AP

Figure 12.13 Cardiac Myofiber Plateau phase Cardiac Myofiber action potential Long refractory period prevent summation in cardiac myofibers Cardiac Myofiber

Figure 12.17 Calcium-induced calcium release

What prevents the AP from being conducted from ventricles back to atria? Fibrous connective tissue between atria and ventricles prevents the conduction of action potential. Only route is via AV node, bundle of His, bundle branches, Purkinje fibers, and to ventriclular myofibers.

Pacemaker Cells in Conducting System Figure 12.14 Pacemaker Cells in Conducting System SA Node or Bundle of His Ectopic Pacemaker Location other than SA Node

Figure 12.22 Intrinsic Rate = 100 beat/min

Effect of “Beta blockers” Figure 12.23 NE EPI ACh mAChR Beta-adrenergic receptors Effect of “Beta blockers” Effect of atropine

Who Cares? Mechanism of action of a Ca++ channel blocker? What effect on blood pressure?

Figure 12.18 1st Heart Sound = Closure of Atrioventricular (AV) valves at beginning of Ventricular Systole 2nd Heart Sound = Closure of Semilunar valves at beginning of Ventricular Diastole

Ventricular Fibrillation & Defibrillation Figure 12.20 Systolic Diastolic Atrial Fibrillation Ejection Fraction = SV/EDV Ventricular Fibrillation & Defibrillation