Chapter 9 Cardiovascular System The Heart Made of cardiac muscle. Hollow, cone-shaped muscular organ. Structure of the Heart The heart is covered by a saclike membrane. Pericardium- tough, fibrous external membrane Parietal- lining the pericardium Visceral- (epicardium) covering the surface of the heart The space between the two internal layers is called the pericardial space (contains fluid) Heart Wall Epicardium- (outer visceral layer) Myocardium- (heart cardiac muscle itself) Endocardium- (lines the chambers of the heart and covers its valves) Chambers of the Heart It has a left and right side The right side receives the blood from the body and sends it to the lungs to be oxygenated. The left side receives the oxygenated blood and sends it to the tissues. Atrium- cranial chamber Interatrial septum- divides the atria Thin walls and are the receiving chambers of the heart Ventricle- ventral chamber Interventricular septum- divides the ventricles Thicker walls to pump the blood. Valves Atrioventricular valves- ensure that blood only flows in one direction Mitral or bicuspid valve- left atrium and ventricle Tricuspid valve- right atrium and ventricle Semilunar valves- arteries into the ventricles located at the base of the pulmonary artery and the aorta. Conduction System SA node (sinoartial) aka pacemaker Consists of cells where the electrical impulses originate Produces atrial contractions Force blood into the ventricle AV node (atrioventricular) Consists of the cells in which the electrical impulses continue down Artioventricular bundle (bundle of His) Continues on as the Purkinje fibers Nerve Function in the Heart Parasympathetic- Supply the SA and AV nodes Slow down the heart rate Reduces impulse conduction Constricts the coronary arteries Sympathetic- Affects the SA and AV nodes Increases the heart rate Dilates the coronary arteries Cardiac Cycle Includes the contraction (systole) and relaxation (diastole) or the chambers of the heart All the chambers do not contract at the same time The two atria contract together and then the two ventricles. Types of blood Vessels Arteries Oxygenated blood is carried from the heart to all structures of the body These are elastic tubes with three layers Arterioles, Capillaries, and Venules Arteries become smaller and smaller till they become arterioles (small arteries) These feed the capillaries (billions of minute, thin walled vessels that communicate with other capillaries) The capillaries distribute blood to the tissues. Other pick-up blood from the tissues (venules) and pass the blood back to the veins then the heart Veins Hollow tubes which are similar to the arteries but have thinner and less elastic walls. They transport blood back to the heart. There are channels that help prevent backflow. Blood Structure 60% plasma (liquid) 40% formed elements Functions Distributes nutrients Collects waste products of metabolism Carries hormones of the different ductless glands Maintains the fluid content of the tissues Serves as a temperature regulator for the body Blood volume is usually 6% to 8% of body weight. Plasma Clear, straw-colored, liquid portion of blood. Approximately 90% water and 10% solutes One of the solutes is fibrinogen, important in blood clotting Serum- plasma will all clotting elements removed. Blood Cells Erythrocytes Extremely small, nonnucleated disks Contain hemoglobin (heme- iron and globin- protein) Anemia- not having enough iron Leukocytes Much less numerous then erythrocytes, colorless, have nucleus. Granulocytes Originate in bone marrow Lobed nuclei Cytoplasm with fine granules Classified by staining characteristics Neutrophils Red and blue stain granules Phagocytosis (engulfs invading organisms) Eosinophils Orange or yellow acid dye-staining granules Detoxify foreign proteins from allergens and parasitic infections Basophils Purple Function is not sure, but they could prevent coagulation Agranulocytes Originate in lymphatic organs No granules in cytoplasm Round horseshoe shaped nucleus Lymphocytes Rounded nucleus Phagocytosis function and antibody formation Monocytes Horseshoe shaped nucleus Phagocyotsis Blood Pressure Systolic pressure- produced by the blood pressing against the walls of the arteries during the contraction of the ventricles. Diastolic pressure- produced by the blood pressing against the walls of the arteries during the relaxation of the ventricles. Circulation of the Blood Tracing the Circulation Left Ventricle Arteries Arterioles Capillaries of the Body Tissue Venules Veins Right Atrium Right Ventricle Pulmonary Artery Arterioles Capillaries of the Lungs Venules Pulmonary Veins Left Atrium Left Ventricle The Lymphatic System Considered part of the circulatory system because it is made up of fluid called lymph (comes from tissue fluids) Lymph is an almost colorless fluid rich in white blood cells and it circulates through the lymphatic vessels The Lymph Glands Lymph glands (nodes) are numerous sacs along the vessels. They vary in size from dots to bean-sized. They are identified by their location. They filter and remove bacteria and malignant cells. They can be inflamed or swollen with ingested bacteria or toxins. They make lymphocytes and monocytes. The Spleen A large, flatten, oval-shaped gland like organ. Dark red in color Located on the left side of the abdominal cavity. The spleen enlarges during disease and increases in size with age. Function: Hemopoiesis- formation of lymphocytes, monocytes, and plasma cells Phagocytosis- removal of destructive microorganisms The Tonsils These are three pairs of small, round, masses of lymphoid tissue that filter out bacteria or other foreign matter Palatine- located at the back of the throat Lingual- located at the root of tongue Pharyngeal- located at the roof of the pharynx The Thymus Grayish, pink structure of lymph tissue, cranial to the heart Produces cells that destroy foreign substances and forms lymphocytes