For sophomores and juniors interested in medical school at: A visit by Dr. Jim Stallworth and other guests from USC School of Medicine in Columbia, SC. In RMSC 122 (The Pit) starting at 6:30pm, Tuesday Nov 13 th. Presentation and discussion on admissions and opportunities.

Abstracts and Test 2 Earn up to 5 points for Test # 2 based on topics of Frog Heart Lab: –Regulation of pacemaker cells by temperature, hormones, neurotransmitters, antagonists –Heart block: 1 st, 2 nd, and 3 rd degree –The conducting system –Strategies for prolonging survival of in vitro organs Cardiac Cycle Animation

1QQ #25 for 10:30 Write the number of the one you choose to answer. 1.Which is more serious and why: atrial fibrillation or ventricular fibrillation? 2.Explain the Frank-Starling Law of the Heart in terms of what happens in cardiac myofiber sarcomeres as end-diastolic volume exceeds 400 ml. 3.What are three ways by which stroke volume can be increased?

1QQ #25 for 11:30 Write the number of the one you choose to answer. 1.What is potentially dangerous about cardiac hypertrophy that accompanies rigorous physical training? 2.Explain the Frank-Starling Law of the Heart in terms what happens in cardiac myofiber sarcomeres as venous return increases. 3.What are the effects of sympathetic stimulation on cardiac myofibers?

CO = HR x SV 5L/min = 72 beat/min x 70 ml/beat 35 L/min = ? beat/min x ? ml/beat S 11 Factors that control Cardiac Output by changing heart rate and stroke volume. + sympathetic - parasympathetic VR and EDV (FSLoH) Contractility (catecholamines) Afterload (MAP)

Fig Even persons with heart transplants can adjust CO in the absence of innervation of heart. Summary of Factors that Regulate Cardiac Output S 12 Exercise………increase CO

The report CNN website

S 13 Heart is pump that generates pressure gradient. Blood flows through vessels, which have resistance. Arterioles have greatest resistance and create “backpressure” in the arteries and aorta. Mean Arterial Pressure = diastolic +1/3(systolic – diastolic) = /3(120-70) = = 87 mm Hg

MAP = CO x TPR Mean Arterial Pressure = Cardiac Output x Total Peripheral Resistance MAP = (HR x SV) x TPR S 14 Who Cares? Hemorrhage Diagram from memory on Friday November 30 th.

Name _________________________________________ On the back side of this page, create a diagram for the following. Your response must be confined to the reverse side of this page and you must write legibly. Your response will count 15-20% of the grade on Test 3 and should require no more than 15 minutes to complete at the beginning of class on Friday November 30 th. Beginning with a loss of about 1 liter of blood from a vein, diagram the early events associated with hemorrhage and the negative feedback responses to hemorrhage in a well-organized diagram. Write legibly! Completeness, accuracy, and detail, together with the proper sequence earn maximal points. The following abbreviations can be used: AI, AII, JGA, mAChR, Hct, Q, SV, EF, RBC, HR, EDV, ACh, ANH, ADH, CO, TPR, EPO, VR, MAP, EPI, NE, SAN, aAdR, bAdR, Symp (sympathetic), Parasymp (parasympathetic), PV, r (radius), Pc, fAP (frequency of action potentials.) Any other abbreviations must be defined. "If in doubt, write it out!" Use single headed arrows (→) to indicate sequential relationships and doubled-stemmed arrows to indicate increases or decreases.

Pressure gradients in systemic vessels

Velocity in systemic vessels Why is velocity slowest in capillaries and venules?

Flow =ml/min = Riders/min past a location Velocity = m/sec for each rider Velocity slows for exchange

Diameter of systemic vessels by type

Cumulative cross sectional area of vessels by type Why is velocity slowest in capillaries and venules?

Properties of Blood Vessels Arteries Arterioles Capillaries Venules Veins Elastic, low compliance, large diameter, low resistance vessels Variable Resistance vessels Exchange Capacitance vessels, high compliance, low pressure, valves for unidirectional flow All vessels and heart chambers lined with ENDOTHELIAL cells (simple squamous) Wall = simple squamous endothelium No smooth muscle; cannot change diameter S 1

Fig Elastic recoil of stretched arterial walls during ventricular systole maintains arterial pressure during diastole as blood drains into arterioles. Point of Confusion: Smooth muscles in arterial walls DO NOT rhythmically contract, do not pump! Atherosclerosis S 4 Stretching elastic connective tissue Recoil of elastic connective tissue

Elastic recoil maintains internal pressure without expending energy Arteries are a pressure reservoir to maintain pressure between during ventricular diastole and to keep blood flowing to arterioles during diastole.

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 Mean Arterial Pressure. MAP = CO x TPR Poiseulle’s Equation S 5

Fig S 6 Heart Arteries Arterioles Kidneys Gut Sk. Muscle Skin CNS Totol Peripheral Resistance Mean Arterial Pressure Cardiac Output

What regulates the smooth muscle of arterioles? Extrinsic controls:Intrinsic controls:

Fig Metabolic autoregulation, flow autoregulation, myogenic autoregulation No parasympathetic innervation of arterioles! Importance of sympathetic “tone.” Metabolic vasodilators S 8

Who Cares? Migraine headaches and sumatriptans (agonists for 5-HT 1 receptors) to stimulate vasoconstriction.