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BIOL 4510 Lecture 1 2013-09-10.pdf

23 Pages

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BIOL 4510
Robert G Tsushima

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BIOL4510/KINE4510 Lecture 1: Cardiac Physiology and Cell Biology September 10, 2013 Dr. Robert Tsushima [email protected] Physiology Circulatory system In small single cell organisms or animals < 1 mm in diameter, movement of molecules can occur easily by diffusion or cell transport from the external environment. However, with larger multicellular organisms, diffusion is inadequate to provide the necessary nutrients, gases, salts or removal of waste. Major components of a circulatory system 1) a pump 2) a conduit or vascular system Closed Circulatory System Ø vertebrates and some invertebrates Ø blood flows in a continuous circuit Ø small volume (5-10% of the body volume) Ø high pressure Ø can alter velocity and distribution of blood flow rapidly Mammalian Circulatory System The heart is important for circulating oxygenated blood to the body, and to deliver venous blood to the lungs. This is achieved through the electromechanical properties of the heart. The intrinsic electrical network is coupled to the mechanical properties, which allow the heart to beat. The heart is a pump, a battery and an endocrine organ. 1 Anatomy of the Heart Anterior View Posterior View 2 Heart Wall The heart wall is comprised o f three distinctive layers: 1) ___________________________ 2) ___________________________ 3) ___________________________ The _____________________is the outermost heart layer, and is also known as the visceral layer of serous pericardium. It is c omposed of simple squamous epithelium underlined by fat As we age, more fat is deposited in the epicardium and this layer becomes thicker and fattier. The ____________________is the middle layer of the heart wall composed primarily of cardiac muscle tissue, and is the thickest of the three heart wall layers. The ____________________covers internal surface of the heart and the external surfaces of the heart valves. It is composed of a thin endothelial layer of cells and connective tissue under the endothelium 3 Heart Valves Ensure blood flows in proper direction Left A-V valve (bicuspid, mitral) between left atrium and left ventricle; valve opens when ______________________ Right A-V valve (tricuspid) between the ri ght atrium and right ventricle; valve opens when Aortic semilunar valve between left ventricle and aorta; valve opens when ________________________ Pulmonary semilunar valve between right ventricle and pulmonary artery; valve opens when ________________________ 4 5 Cardiac Cycle 6 Cardiac Electrical Activity Electrocardiogram • Electrical activity is recorded by electrocardiogram (ECG) • P wave corresponds to depolarization of SA node • QRS complex corresponds to ventricular depolarization • T wave corresponds to ventricular repolarization • Atrial repolarization record is masked by the larger QRS complex 7 Cardiac Cycle – Electrical Activity Cardiac Cycle - Pressure 8 Left versus Right Pressures Right ventricle Left ventricle Coronal Section Right Ventricle vs. Left Ventricle ♥ normally has less muscle mass than the left ventricle and creates less pressure when i t contracts ♥ the right ventricle is pumping deoxygenated blood ♥ the right ventricle pumps the same amount of blood with each contraction ♥ pulmonary resistance is less than systemic resistance Cardiac Cycle - Volume 9 Cardiac Cycle – Heart Sounds Heart sounds (lub -dup) are associated with closing of heart valves First sound occurs as ________ _________________ valves close and signifies beginning of __________________________ Second sound occurs when________ _______________ valves close at the beginning of ventricular _______________________ Wiggers Diagram 10 Definitions • Inotropy (inotropic) • Chronotropy (chronotropic) • Lusitropy (lusitropic) • Dromotropy (dromotropic) For example, ____________ _______has _________ inotropic, chronotropic, lusitropic and dromotropic effect on the heart Ventricular Pressure and t he Pressure-Volume Relationship 11 Diastole – the phase when the myocardium is relaxed Systole – the phase when the myocardium is contracting Left Ventricular Pressure-Volume Loop U Systolic Pressure Curve P L Diastolic Pressure Curve LV VOLUME 12 Left Ventricular Pressure -Volume Loop Increased Contractility Decreased Contractility E R E P R L L LV VOLUME LV VOLUME Increased Ventricular Filling E R L LV VOLUME 13 Cell Biology There are 3 different muscle types: smooth muscle skeletal, and cardiac Although all 3 are capable of contracting, their morphology is quite different. Skeletal Muscle The morphology of skeletal muscle is more complex than the other 2 muscle types. Functional Organization Skeletal muscle has 3 layers of connective tissue Outer epimysium ( epi – on; mys – muscle) Collagen fibers Central perimysium ( peri – around) Collagen fibers and elastic fibers; blood vessels and nerve Inner endomysium (endo – inside) Collagen fibers 14 The collagen fibers of the epimysium, perimysium and endomysium come together at the end of muscle to form the tendon or aponeurosis (broad sheet of tendon). The muscle is divided into bundles (fascicles) which are surrounded by the perimysium Each muscle fascicle is divided into muscle fibers. Each muscle fiber is divided into myofibrils. Each skeletal muscle conta ins 100s – 1000s of myofibrils Each myofibril is 100 µm wide and can equal to the entire length of the muscle (30 cm or more) Muscle Fiber The muscle fiber is comprised of: 15 Myofibrils – contractile protein; myofilaments Mitochondria – located on the periphery Sarcolemma – plasma membrane The sarcolemma forms specialized invaginations
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