6 - Cardiovascular Physiology I Steve Cala Ph.D Associate...

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Unformatted text preview: Cardiovascular Physiology I Steve Cala, Ph.D Associate Professor Department of Physiology [email protected] Three kinds of pressure differences in blood vessels 1.  2.  3.  Driving pressure (from heart) Transmural pressure Hydrostatic pressure (from standing) MAP = [(2 x DBP) + SBP] / 3 Laplace’s Law T = ΔP · r NUMBER 1 8000 10 E07 4 E10 AREA (cm2) 4 63 141 2800 (~25% are open) Can you explain “cross-sectional area” and how it differs from radius and diameter and resistance? Is there an inverse relationship between cross-sectional area and resistance? Poiseuille (pwa-zwe) ’s Law for an ideal fluid predicts a very steep dependence of vascular resistance on radius Flow = P r4 8ηL (and P = F x R, so R = P / F, therefore) Resistance = 8ηL x 1 P r4 P = “driving pressure” Total volume flow is the same at any level of arborization Flow = F (aorta) = F (arterioles) = F (capillaries) … etc. Flow = [A · v] (aorta) = [A · v] (arterioles) … etc. Blood volumes 85 % of the blood is in the systemic circulation Only 15 % of the blood is under high pressure Most of the blood in the body resides in systemic veins Major actions of drug groups used against angina pectoris Organic Nitrates Decrease CO by decreasing preload Reduce spasm Ca channel blockers Decrease CO by decreasing afterload, contractility, HR Reduce spasm Beta blockers Decrease CO by decreasing afterload,contractility and HR Reduce spasm PSL 7030/7031 Cardiovascular Physiology I A. B C. D. E. F. G. H. I. J. K. L. M. Basic anatomy of the heart and cardiovascular system Preview of some key concepts The cardiac cycle Cardiac output: key concepts Control of cardiac output Mechanisms for control of cardiac output Basic anatomy of the vasculature Blood vessels and blood pressure Local control of pressure Heart cell structure Ca2+ homeostasis and excitation-contraction coupling Electrophysiology of the heart Electrocardiography Exams 1.  Exam questions will primarily be taken from information in handout 2.  Challenges to an exam question must be within ~ 48 h of the exam 3.  Changes in any exam question will apply equally to all students 4.  Students are unlikely to receive individual responses to their challenges Question from 2006 exam 6. Perfusion pressure is roughly the same across most tissues. Which one of the following explains this best? A. Pulse pressures are the about the same throughout the circulatory system B. Blood flow equals resistance times pressure change C. Arterial pressures exceed venous pressures by similar amount throughout the circulatory system D. Autonomic tone is very efficient in controlling blood flow E. Reflex hyperemia regulates capillary blood flow Question from 2006 exam Total peripheral resistance is approximately equal to: A. B. C. D. E. Heart rate times stroke volume Perfusion pressure divided by cardiac output Radius to the 4th power times a constant Heart rate times blood pressure 120 ohms Question from 2006 exam Hydrostatic pressure: A. B. C. D. E. Only affects arterial pressure Only affects venous pressures Has equal effects on arterial and venous pressures Has its greatest effect on perfusion pressures Has no effects on blood pressure Question from 2006 exam Compliance of the aorta explains which of the following: A. its inability to maintain significant aortic blood pressure during diastole B. its increase in volume with increased pulse pressure C. its relative lack of response to sympathetic stimulation D. A and B E. A, B, and C Question from 2008 exam The greatest drop in systemic blood pressure occurs between which two types of blood vessels? A. B. C. D. E. Venules and large veins Vena cava and pulmonary vein Capillaries and right atrium Arteries and capillaries Aorta and arteries Heart cell structure and Ca2+ cycling Ostium of the coronary arteries Langendorff perfusion Common muscular dystrophies Mutations in the gene for dystrophin are among the most common of the muscular dystrophies. The gene for dystrophin is huge, containing 79 exons spread out over 2.3 million base pairs of DNA. Thus this single gene represents about 0.1% of the entire human genome (3 x 109 bp) Duchenne muscular dystrophy is caused by mutations that cause a frameshift usually causing premature termination in mRNA. Becker muscular dystrophy results from removal of certain exons but preserves the correct reading frame. Glycosylation defects: A new mechanism for muscular dystrophy Grewal and Hewitt, Human Molecular Genetics, 2003, Vol. 12, Structure of striated muscle cells ...
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