Cardiovascular System PDF

Session 1 Cardiovascular System w A closed system of the heart and blood vessels Ø Anterior Surface – deep in the sternum – The heart pumps blood and ribs – Blood vessels allow blood to c...

Session 1 Cardiovascular System w A closed system of the heart and blood vessels Ø Anterior Surface – deep in the sternum – The heart pumps blood and ribs – Blood vessels allow blood to circulate Ø Inferior Surface – portion that rests to all parts of the body mostly on the diaphragm and found between w Functions of the cardiovascular system the apex and right border – Transport oxygen, nutrients, cell Ø Right Border – faces the right lung and wastes, hormones to and from cells extends from inferior surface to the base – Ø Left Border – “Pulmonary Border”, faces ANATOMY OF THE HEART left lung and extends from the base to the Ø Hollow cone shaped organ apex Ø Weighs less than a pound Anatomy of the Heart Ø Approximately the size of a person’s fist : 12 cm. long, 9 cm wide, 6 cm thick w Coverings of the heart Ø Located in the thoracic cavity, between the – Pericardium—a double-walled sac lungs in the inferior mediastinum Fibrous pericardium is loose and superficial Apex – pointed end of the heart, directed toward left Serous membrane is deep to the fibrous pericardium hip & rests on the diaphragm and composed of two layers Base – based points toward right shoulder 1. Parietal pericardium: outside layer that lines Location of the heart within the thorax the inner surface of the fibrous pericardium 2. Visceral pericardium: next to heart; also known as the epicardium Serous fluid fills the space between the layers of pericardium, called the pericardial cavity w Walls of the heart 1. Epicardium Outside layer; the visceral pericardium 2. Myocardium Middle layer Mostly cardiac muscle 3. Endocardium Inner layer known as endothelium LIK  Chambers and Associated Great Vessels Chambers and Associated Great Vessels w Four chambers of the heart w Interatrial septum 1. Atria (right and left) – Separates the two atria longitudinally Receiving chambers w Interventricular septum Assist with filling the – Separates the two ventricles ventricles longitudinally Blood enters under low pressure 2. Ventricles (right and left) Discharging chambers Thick-walled pumps of the heart During contraction, blood is propelled into circulation w Heart functions as a double pump – Arteries carry blood away from the heart – Veins carry blood toward the heart w Double pump – Right side works as the pulmonary circuit pump – Left side works as the systemic circuit pump LIK  w Pulmonary circulation CHAMBERS OF THE HEART w Blood flows from the right side of the heart to Atria – upper chambers ; entry halls the lungs and back to the left side of the heart Ventricles – lower chambers ; little bellies w Blood is pumped out of right side Auricle – wrinkled pouchlike structure on the through the pulmonary trunk, which anterior surface of each atrium splits into pulmonary arteries and - slightly increases the capacity of the atrium to hold takes oxygen-poor blood to lungs greater blood volume w Oxygen-rich blood returns to the heart from the lungs via pulmonary veins Heart Valves w Allow blood to flow in only one direction, to w Systemic circulation prevent backflow w Oxygen-rich blood returned to the left side of – Atrioventricular (AV) valves— the heart is pumped out into the aorta between atria and ventricles w -Blood circulates to systemic arteries and to all Left AV valve: bicuspid body tissues (mitral) valve w -Left ventricle has thicker walls because it Right AV valve: tricuspid pumps valve w blood to the body through the systemic circuit – Semilunar valves—between ventricle w Oxygen-poor blood returns to the right atrium and artery via systemic veins, which empty blood into the Pulmonary semilunar valve superior or inferior vena cava Aortic semilunar valve w AV valves – Anchored the cusps in place by chordae tendineae to the walls of the ventricles – Open during heart relaxation, when blood passively fills the chambers – Closed during ventricular contraction w Semilunar valves – Closed during heart relaxation LIK  – Open during ventricular contraction w Valves open and close in response to pressure changes in the heart LIK What Does C-V System do? Blood supply to heartwall w Circulate blood throughout entire body for – ransport of oxygen to cells Right and Left Coronary Arteries – Transport of CO2 away from cells – Branch from Ascending Aorta – Transport of nutrients (glucose) to -Have multiple branches along heart cells – Sit in Coronary Sulcus – Movement of immune system -Coronary Heart Disease components (cells, antibodies) Cardiac Veins – Transport of endocrine gland -Coronary Sinus (largest) secretions – Many branches feed into sinus – Sit in Coronary Sulcus How does it do it? w Heart is pump w Arteries and veins are main tubes (plumbing) – Arteries Away from Heart – Veins to Heart w Diffusion happens in capillaries (oxygen, CO2, glucose diffuse in or out of blood) GREAT VESSELS Aorta IVC, SVC Pulmonary Trunk Pulmonary Veins Cardiac Circulation w Blood in the heart chambers does not nourish the myocardium Physiology of the Heart w The heart has its own nourishing circulatory w Intrinsic conduction system of the heart system consisting of: – Cardiac muscle contracts – Coronary arteries—branch from the spontaneously and independently of aorta to supply the heart muscle nerve impulses with oxygenated blood – Spontaneous contractions occur in a – Cardiac veins—drain the myocardium regular and continuous way of blood Atrial cells beat 60 times – Coronary sinus—a large vein on the per minute posterior of the heart; receives blood Ventricular cells beat from cardiac veins 20−40 times per minute w Blood empties into the right atrium via the Need a unifying control coronary sinus system—the intrinsic conduction system (nodal system) w Intrinsic conduction system of the heart – Two systems regulate heart activity Autonomic nervous system Intrinsic conduction system, orthe nodal system – Sets the heart rhythm – Composed of special nervous tissue – Ensures heart muscle depolarization in one direction only (atria to ventricles) – Enforces a heart rate of 75 beats per minute LIK  w Intrinsic conduction system of the w Intrinsic conduction system of the heart heart Components include: a. Tachycardia—rapid heart a. Sinoatrial (SA) node rate, over 100 beats per Located in the right atrium minute Serves as the heart’s b. Bradycardia—slow heart pacemaker rate, less than 60 beats b. Atrioventricular (AV) node is per minutes at the junction of the atria and ventricles c. Atrioventricular (AV) bundle (bundle of His) and bundle branches are in the interventricular septum d. Purkinje fibers spread within the ventricle wall muscles w The sinoatrial node (SA node) starts each heartbeat a. Impulse spreads through the atria to the AV node b. Atria contract c. At the AV node, the impulse is delayed briefly d. Impulse travels through the AV bundle, bundle branches, and Purkinje fibers e. Ventricles contract; blood is ejected from the hear LIK  The heart, located in the thorax, is flanked laterally by the lungs and enclosed I a multi-layered pericardium. The bulk of the heart wall (myocardium) is composed of cardiac muscle. The heart has hour hollow chambers – two atria (receiving chambers) and two ventricles (discharging chambers), each lined with endocardium. The heart is divided longitudinally by a septum. The heart functions as double pump. The right ventricle is the pulmonary pump (right ventricle to lungs to left atrium). The left ventricle is the systemic pump (left ventricle o body tissues to right atrium) Four valves prevent backflow of blood in the heart. The AV valves (mitral or bicuspid, and tricuspid) prevent backflow into the atria when the ventricles are contracting. The semilunar valves (pulmonary and aortic) prevent backflow in the ventricles when the heart is relaxing. The valves open and close in response to pressure changes in the heart. The myocardium is nourished by the coronary circulation, which branches off the aorta and consists of the right and left coronary arteries and their branches, and is drained by the cardiac veins and the coronary sinus. Cardiac muscle is able to initiate its own contraction in a regular way, but its rate is influenced by both intrinsic and extrinsic factors. The intrinsic conduction system increases the rate of heart contraction and ensures that the heart beats as a unit. The SA node is the heart’s pacemaker. Extrinsic factors include neural and hormonal stimuli. LIK