THE HEART AND THE CARDIOVACULAR SYSTEM INGLÉS TÉCNICO I GENERACIÓN 2010 FACULTAD DE VETERINARIA, UDELAR Prof. Carmen Silvia Gallo Muniz Matías Fiorelli Esteban Pérez Marie Claire Van Wassenhove Teresa López

THE HEART The heart is the pump that pushes the blood around the blood vessels of the circulatory system. It pumps oxygen-rich blood throughout the body and oxygen-poor blood to the lungs.

LOCATION The heart is situated in the thorax between the lungs and is protected by the rib cage. In some animals it is displaced slightly to the left-hand side.

ANATOMY OF THE HEART It is divided into four chambers (right and left atria and right and left ventricles). Valves stop blood flowing backwards. The right and left atrio-ventricular valves prevent blood in the ventricles from flowing back into the atria. The semilunar valves at the entrance of the pulmonary artery and aorta prevent blood flowing back into the ventricles.

ELECTRIC SYSTEM OF THE HEART The heart has two areas that initiate impulses, the SA or sinoatrial node and the AV or atrioventricular node. The heart also has special fibers called Purkinje fibers that conduct the impulses five times more rapidly to the surrounding cells. Purkinje fibers form a pathway for conduction of the impulse that ensures that the heart muscle cells contract in the most efficient pattern The SA node is located in the wall of the right atrium, near the junction of the atrium and the superior vena cava

HEART The heart consists of two muscular pumps, left and right, which lie side by side. Each side is divided into a smaller upper chamber or atrium, and a lower chamber or ventricle. The left ventricle has a thicker wall because it has to pump blood around the body; the thinner-walled right ventricle pumps blood to the lungs.

CIRCULATORY SYSTEM Our heart has two circulatory systems: The pulmonary circulation is a short loop from the heart to the lungs and back again. The systemic circulation sends blood from the heart to all the other parts of our bodies and back again.

PULMONARY CIRCULATION The blood that comes from the body enters the right atrium of the heart through the large veins called venae cavae. It goes from the right atrium to the right ventricle, which squeezes it out by the pulmonary artery. It goes to the lungs where it picks up oxygen. Loaded with oxygen it returns by the pulmonary veins to the left atrium.

SYSTEMIC CIRCULATION The blood comes from the lungs through the pulmonary veins and enters the left atrium. The left atrium squeezes and the blood passes to the left ventricle. The left ventricle then squeezes and the blood leaves the heart through the aorta.

SUPERIOR VENA CAVA CARRIES BLOOD FROM THE HEAD, ARMS AND UPPER BODY BACK TO THE HEART. INFERIOR VENA CAVA CARRIES BLOOD FROM THE LOWER BODY BACK TO THE HEART. THE ONLY ARTERIES THAT CARRY BLOOD WHICH IS POOR IN OXYGEN, TO THE LUNGS THE AORTA IS THE BIGGEST BLOOD VESSEL, IT ARCHES OUT OF THE HEART AND DOWN TOWARDS THE LOWER BODY

CORONARY VESSELS The heart as every organ in our body needs a supply of blood to bring oxygen. It cannot get it from the blood within its chambers because it passes too quickly and under a great pressure, and in the right chamber is low in oxygen. It recives blood from a system of small arteries that branch from the aorta, the coronary arteries. They cover the heart, dividing and sending small branches into the heart.

DIASTOLE ATRIAL SYSTOLE VENTRICULAR SYSTOLE ATRIA AND VENTRICLES RELAXED BLOOD FILLS THE ATRIA SEMILUNAR VALVES ARE CLOSED ATRIOVENTRICULAR VALVES ARE OPENED BOTH ATRIA CONTRACT AND SQUEEZ BLOOD TO THE VENTRICLES THE VENTRICLES CONTRACT AND PUSH BLOOD OUT OF THE HEART SEMILUNAR VALVES ARE OPENED ATRIOVENTRICULAR VALVES ARE CLOSED

PERICARDIUM It is a double-walled sac that contains the heart and the roots of the great vessels. There are two layers to the pericardial sac: the fibrous pericardium and the serous pericardium. The serous pericardium is divided into two layers, the parietal pericardium, which is fused to the fibrous pericardium, and the visceral pericardium, which is part of the epicardium. The epicardium is the layer immediately outside of the heart muscle.

CARDIAC MUSCLE The heart is a hollow bag made of cardiac muscle Intercalated disks contain gap junctions. The action potential travels through the cells connected together forming a functional syncytium in which cells function as a unit.

BLOOD VESSELS There are 3 types of blood vessels: Arteries Veins Capillaries Arteries divide into smaller vessels called arterioles, which divide into a network of capillaries. Blood then passes to venules and veins.

ARTERIES: CARRIE BLOOD FROM THE HEART. THEY HAVE THICK WALLS THAT CAN STAND THE HIGH PRESSURE PRODUCED WHEN THE HEART BEATS VEINS: CARRIE BLOOD BACK TO THE HEART. THEY HAVE THIN WALLS BECAUSE THE PRESSURE INSIDE IS LOW CAPILLARIES: ARE THIN BLOOD VESSELS THAT CARRY BLOOD BETWEEN ARTERIOLES AND VENULES. THEY SUPPLY CELLS WITH OXYGEN AND NUTRIENTS AND REMOVE WASTE

BLOOD BLOOD TRAVELS INSIDE THE VESSELS SUPPLY OXYGEN FROM THE LUNGS AND NUTRIENTS FROM THE DIGESTIVE SYSTEM CARRY AWAY WASTE TO THE KIDNEYS HELPS DEFEND THE BODY AGAINST INFECTION DISTRIBUTES HEAT AROUND THE BODY AND HELPS TO MANTAIN THE BODY TEMPERATURE