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Anatomy of the Cardiovascular System. Cardiovascular System. As Also circulatory system Consists of: the heart, arteries , veins , capillaries. Heart. Four chamber muscular organ Comparable to the size of a closed fist Located in the mediastinum Behind sternum
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Cardiovascular System • As Also circulatory system • Consists of: • the heart, • arteries, • veins, • capillaries
Heart • Four chamber muscular organ • Comparable to the size of a closed fist • Located in the mediastinum • Behind sternum • Between 2nd and 6th ribs • Between T5-T8 • Apex – base of heart • Located at the 5th intercostal space
Coverings of the Heart • Pericardium – loose fitting sac surrounding the heart • Fibrous pericardium – tough, loose-fitting, inelastic • Serous pericardium • Parietal layer: lines the inside of the fibrous pericardium • Visceral layer: adheres to outside of the heart • Pericardial space: between parietal and visceral layer • Filled with 10-15mL of pericardial fluid • Decreases friction
Walls of the Heart 2. Epicardium– outer layer • Epicardium = serous pericardium 3. Myocardium – thick, contractile layer composed of cardiac muscle cells • Intercalated disks contain many gap junctions • Allow cardiac muscle cells to function as a single unit syncytium 4. Endocaridium– interior of cardiac wall • Endothelial tissue • Covers projections of myocardial tissue called trabeculae
Chambers of the Heart • Atria – two superior chambers • “Receiving chambers” • Blood from veins enters atria • Ventricles – two inferior chambers • “pumping chambers” • Thick muscular walls to increase force of pumping action • Left > right • Separated by interventricular septum
Valves of the Heart • Permit blood flow in one direction during circulation • Atrioventricular valves (AV valves) • Also cuspid valves • Between atria and ventricles • Semilunar (SL valves) • Between R ventricle and pulmonary arteries and L ventricle and aorta
Atrioventricular Valves • Tricuspid valve • Btwn R atrium and ventricle • 3 flaps of endocardium • Connected to ventricular papillary muscle via chordae tendinae • Bicuspid valve • Btwn L atrium and ventricle • Also called mitral valve • Two flaps of endocardium
Semilunar Valves • Pulmonary semilunar valve • Btwn R ventricle and pulmonary trunk • Aorta semilunar valve • Btwn L ventricle and aorta
Chambers & Valves Trace the blood flow through the heart
Blood Supply to the Heart • Right and left coronary arteries • First branches off aorta • Right coronary artery right marginal artery & posterior interventricular artery • Left coronary artery circumflex artery & anterior interventricular artery • Most of the blood goes to the L ventricle • In 50% of the population, the R coronary artery is dominant
Blood Supply to the Heart • Anastomosis: Connections between blood vessels that allow for collateral circulation • Few exist between large branches of coronary arteries • In presence of an obstruction in a large artery ischemia will result to a large area of tissue • Myocardial infarction (MI) (aka heart attack) • Anastomoses do exists between smaller branches of the R and L coronary arteries
Blood Supply to the Heart • After traveling through the capillaries of the heart, blood empties into the R atrium via the coronary sinus
Warming Up I • The apex of the heart rests on the: • True/False: The epicardium and the fibrous pericardium are the same structure. • What is the correct order of the layers of the heart from outside to inside? • The ____________ connect the cuspid valves to the papillary muscles. • What is an anastomosis? • What is also known as the pacemaker of the heart?
Types of Blood Vessels • Artery – carries oxygenated blood away from the heart • “distributors” • Arteriole: small artery • Precapillary sphincters: regulate the blood flow into capillaries
Types of Blood Vessels • Vein – carries unoxygenated blood towards the heart • Great ability to stretch (capacitance) • Function as reservoirs: blood pools in the valves then is pushed forward from the pumping pressure • Venules: small vein
Types of Blood Vessels • Capillaries – arterial system switches to venous system • “primary exchange vessels” • Transport materials to and from the cells • Speed of blood flow decreases to increase contact time • Microcirculation: blood flow between arterioles, capillaries and venules
Structure of Blood Vessels • Tunica adventitia - outermost layer • Fibrous connective tissue • Holds vessels open; prevents tearing of vessels walls during body movements • Larger in veins than arteries • Tunica media – middle layer • Smooth muscle and elastic CT • Helps vessels constrict and dilate • Larger in arteries
Structure of Blood Vessels • Tunica intima – innermost layer • Composed of endothelium • Semilunar valves present in veins • One cell thick in capillaries
Circulatory Routes • Systemic Circulation – blood flow from the L ventricle to the body & back to the R atrium • Pulmonary Circulation – blood flow from the R ventricle to the lungs and back to the L atrium
Arch of aorta Subclavian (L and R) Brachiocephalic common carotid (L and R) Axillary (L and R) Brachial (L and R) Radial Ulnar Abdominal aorta Common iliac External iliac Femoral Popliteal Posterior tibial Anterior tibial Dorsal pedis Systemic Arteries
Superior vena cava Inferior vena cava External jugular Internal jugular Brachiocephalic (L and R) Subclavian (L and R) Cephalic axillary Basilic Median basilic Median cubital Common iliac External iliac Femoral Popliteal Great saphenous Small saphenous Systemic Veins
Fetal Circulation • Two umbilical arteries carry blood to the placenta • The placenta allows for exchange of oxygen and nutrients from the mother. Maternal and fetal blood do NOT mix. • Umbilical vein returns oxygenated blood and enters fetus via the umbilicus • Foramen ovale – hole btwn the R and L atria • Allows for blood to bypass the R ventricle and pulmonary circulation
Fetal Circulation • Ductus arteriosus – small vessel connecting the pulmonary artery and the aorta • Allows for another bypass route from the lungs **Most of fetal blood is a mixture of oxygenated and deoxygenated blood**