Cardiovascular System

Functions of the Cardiovascular System Supply all body tissues with oxygen and nutrients Transport cellular waste products to the appropriate organs for removal from the body

Structures Heart –Hollow muscular organ located between the lungs and above the diaphragm. –Is a very efficient pump that furnishes the power to maintain blood flow throughout both the pulmonary and systemic circulatory systems. –Pulmonary- lungs –Systemic - the body

Heart Cont’d Pericardium –Double-walled membranous sac that encloses the heart –Pericardial Fluid lies between the layers to prevent friction when the heart beats.

Walls of the heart 3 layers –Epicardium – external layer of the heart and also is part of the inner layer of the pericardial sac. –Myocardium – middle and thickest layer, consists of cardiac muscle –Endocardium – the inner lining of the heart, forms the inner surface that comes in direct contact with blood being pumped through the heart.

Blood Supply to the Myocardium Myocardium must have a continuous supply of oxygen & nutrients and the prompt removal of wastes. Coronary Arteries and veins supply the blood needs of the myocardium. If blood supply is disrupted, the myocardium in the affected area dies. This "myocardial death" is painful and is known as a ___________________.

Heart Chambers Heart is divided into left and right sides Each side is divided which forms four chambers Atria – the two upper chambers of the heart, are the receiving chambers. All blood vessels coming into the heart enter here. The atria are separated by the interatrial septum. A septum is a separating wall or partition.

Heart Chambers Cont’d VentriclesVentricles – the two lower chambers of the heart. All vessels leaving the heart emerge from the ventricles. The ventricles are separated by the interventricular septum. The ventricles are the pumping chambers. The ventricular walls are thicker than the atrial walls because the ventricles pump the blood longer distances. The narrow tip of the heart is called the cardiac apex.

Heart Valves Control the flow of blood through the heart. Tricuspid valve – controls the opening between the right atrium and the right ventricle. Pulmonary valve – located between the right ventricle and the pulmonary artery. Mitral Valve (bicuspid valve) – located between the L atrium and the L ventricle. Aortic semilunar valve – located between the L ventricle and the aorta.

Systemic and Pulmonary Circulation Systemic circulation – includes blood flow to all parts of the body except the lungs. Pulmonary circulation – the flow of blood between the heart and lungs

Left Ventricle pumps oxygenated blood to body parts (systemic circulation) Right Ventricle pumps de- oxygenated blood to the lungs (pulmonary circulation) watch

Circulation Cont’d In systemic circulation, oxygen-rich blood flows out of the heart from the left ventricle into the arteries. Oxygen-poor blood returns to the heart through the veins and flows into the right atrium.

Circulation Cont’d In pulmonary circulation, blood flows out of the heart from the right ventricle and through the pulmonary arteries to the lungs. This is the only place in the body where arteries carry oxygen- poor blood. In the lungs, waste material (carbon dioxide) from the body is exchanged for oxygen from the inhaled air. The pulmonary veins carry the oxygen-rich blood into the left atrium of the heart. This is the only place in the body where veins carry oxygen-rich blood.

The Heartbeat The rate and regularity of the heartbeat is determined by electrical impulses from nerves that stimulate the myocardium of the chambers of the heart. Also known as the conduction system, these electrical impulses are controlled by the sinoatrial (S-A) note, atrioventricular (A-V) node, and bundle of His.

Sinoatrial Node Also know as the S-A node, is located in the posterior wall of the right atrium near the entrance of the superior vena cava. Because it establishes the basic rhythm of the heartbeat, it is called the natural pacemaker of the heart. Electrical impulses from the S-A node start each wave of muscle contraction in the heart. The impulse in the right atrium spreads over the muscles of both atria, causing them to contract simultaneously. This contraction forces blood into the ventricles.

Atrioventricular Node Impulses from the S-Anode also travel to the atrioventricular node. Also known and the A-V node, it is located on the floor of the right atrium near the interatrial septum. The A-V node transmits the electric impulses on to the bundle of His.

Bundle of His Located within the interventricular septum. Branches of the bundle of His carry the impulse to the right and left ventricles and the Purkinje fibers. The Purkinje fibers, causes the ventricles to contract simultaneously forcing blood into the aorta and pulmonary arteries.

Heart Sounds When listening to the heart with a stethoscope, two distinct sounds are heard. They are called the “lub-dub” sounds. Heard first is the lub sound. This is caused by the tricuspid and mitral valves closing between the atria and the ventricles. Heard next is the dub sound, which is shorter and higher pitched. It is caused by the closing of the semi lunar valves in the aorta and pulmonary arteries as blood is pumped out of the heart.

Blood Vessels 3 major types of blood vessels: –Arteries – the large blood vessels that carry blood away from the heart to all regions of the body. It is the high oxygen content that gives arterial blood its bright red color. Aorta – the main trunk of the arterial system and begins from the left ventricle of the heart. Coronary artery – branches from the aorta and supplies blood to the myocardium. Arterioles – smaller thinner branches of arteries, carry blood to the capillaries

Blood Vessels Cont’d Capillaries serve as the anatomic units connecting the arterial and venous circulatory systems. They are the smallest vessels in the body. The slower flow of blood through the capillaries allows time for the exchange of oxygen, nutrients, and waste materials between the tissue fluids and the surrounding cells.

Blood Vessels Cont’d Veins – form a low-pressure collecting system to return the waste-filled blood to the heart. –Have thinner walls and are less elastic than the arteries. Contractions of the skeletal muscles cause the blood to flow through the veins toward the heart. –Have valves that allow blood to flow toward the heart but prevent it from flowing away from the heart. –Venules – are small veins that join to form the larger veins.

Blood Vessels cont’d Venae Cavae (singular, Vena Cava) –Two large veins that enter the heart. –The superior vena cava – known as the SVC, brings blood from the upper portion of the body. –Inferior vena cava – know as the IVC, brings blood from the lower portion of the body.

Pulse and Blood Pressure Pulse – the rhythmic expansion and contraction of an artery produced by the pressure of the blood moving through the artery. Blood pressure – a measure of the amount of pressure exerted against the walls of vessels. Systolic pressure – occurs when the ventricles contract, is the highest pressure against the walls of the blood vessels. Diastolic pressure – occurs when the ventricles are at rest, and is the lowest pressure against the walls of the vessels.

Blood pressure is recorded as systolic over diastolic. Normal adult reading is about 120/80 or a little lower. Circulatory Song Circulatory Song Watch it2Watch it