13 November 2009 Cardiovascular Physiology Lab next week: Frog Heart Physiology Abstracts due Today at start of Class.

CO = HR x SV 5L/min = 72 beat/min x 70 ml/beat 35L/min =. beat/min x CO = HR x SV 5L/min = 72 beat/min x 70 ml/beat 35L/min = ? beat/min x ? ml/beat

Summary of Factors that Regulate Cardiac Output Fig. 12.28 Even persons with heart transplants can increase CO in the absence of innervation of heart. 12.28.jpg Notice: No Parasymp innervation of Cardiac Myofibers, Parasymp to Conducting Cells only.

Mean Arterial Pressure = Cardiac Output x Total Peripheral Resistance MAP = CO x TPR MAP = (HR x SV) x TPR

Poiseulle’s equation

Properties of Blood Vessels All vessels and heart chambers lined with ENDOTHELIAL cells (simple squamous) Arteries Arterioles Capillaries Venules Veins Elastic, low compliance, large diameter, low resistance vessels Resistance vessels Exchange Wall = simple squamous endothelium Capacitance vessels, high compliance, low pressure, valves for unidirectional flow

Fig. 12.29 Aorta Brachial or Femoral artery Pusatile flow Damage to artery vs vein 12.29.jpg

6 Fig. 12.39b Analogy: river width and flow 12.39b.jpg

Fig. 12.30 Elastic recoil of stretched arterial walls during ventricular systole maintains arterial pressure during diastole as blood drains into arterioles. Atherosclerosis 12.30.jpg Point of Confusion: Smooth muscles in arterial walls DO NOT rhythmically contract!

Arteries and Arterial Pressure Mean Arterial Pressure Arteriole Arterioles have two main functions: 1) regulate flow to tissues and organs and 2) responsible for Total Peripheral Resistance which influences Blood Pressure. MAP = CO x TPR Poiseulle’s Equation

Fig. 12.50 12.50.jpg

Receptors for other ligands Alpha receptors more common except in skeletal muscle arterioles which have more B2 receptors

Fig. 12.36 3 Used in Nuclear Stress Test 12.36.jpg Metabolic autoregulation, flow autoregulation, myogenic autoregulation

Fig. 12.36 3 No parasympathetic innervation of arterioles! Metabolic vasodilators No parasympathetic innervation of arterioles! Importance of sympathetic “tone.” 12.36.jpg Metabolic autoregulation, flow autoregulation, myogenic autoregulation