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Class 6 Cardiovascular System Blood Heart Pericardium Fibrous Pericardium Parietal Pericardium Visceral Pericardium Walls of the Heart • Epicardium (AKA Visceral Pericardium) – Outer layer • Myocardium – Muscle layer • Endocardium – Inner layer that forms valves & lines chambers Chambers of the Heart Chambers and Valves of the Heart • Right atrium – Receives lowoxygen blood returning from body tissue through superior vena cava and inferior vena cava • Left atrium – Receives highoxygen blood from lungs • Right ventricle – Pumps blood from right atrium to lungs • Left ventricle – Pumps oxygenated blood to body Blood Flow Through Heart 10 1 Blood enters right atrium from superior and inferior vena cava. Aorta Left pulmonary artery 11 5 5 9 Pulmonary trunk Superior vena cava Right pulmonary veins 4 6 6 Left atrium 1 Aortic valve 7 3 Right atrium 8 2 Right AV (tricuspid) valve Left AV (bicuspid) valve Left ventricle 3 Contraction of right ventricle forces pulmonary valve open. 4 Blood flows through pulmonary valve into pulmonary trunk. 5 Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2. 6 Blood returns from lungs via pulmonary veins to left atrium. 7 Blood in left atrium flows through left AV valve into left ventricle. 8 Contraction of left ventricle (simultaneous with step 3 ) forces aortic valve open. 9 Blood flows through aortic valve into ascending aorta. Right ventricle Inferior vena cava Left pulmonary veins 2 Blood in right atrium flows through right AV valve into right ventricle. 11 10 Blood in aorta is distributed to every organ in the body, where it unloads O2 and loads CO2. 11 Blood returns to heart via venae cavae. blood pathway travels from the right atrium through the body and back to the starting point Coronary Circulation Cardiac Conduction System 1 SA node fires. Right atrium 2 Excitation spreads through atrial myocardium. 2 1 Sinoatrial node (pacemaker) Left atrium 2 Atrioventricular node Atrioventricular bundle Purkinje fibers Purkinje fibers 3 Bundle branches 4 5 3 AV node fires. 4 Excitation spreads down AV bundle. 5 Purkinje fibers distribute excitation through ventricular myocardium. Electrocardiogram (ECG or EKG) • composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs and chest 0.8 second R R Millivolts +1 PQ segment ST segment T wave P wave 0 PR Q interval S QT interval QRS interval –1 Atria contract Ventricles contract Atria contract Ventricles contract Blood Vessels Capillaries Blood Pressure Systole Contraction phase Diastole Relaxation phase Venous Blood Flow • Skeletal Muscle Action – Valves • Respiratory Movements – Valves • Venous Constriction Arterial System Venous System Hepatic Portal System Blood • Functions of Blood – Transportation of Substances • Gases, nutrients, wastes, etc – Body Temperature Regulation • Dermal blood vessels either dilate or constrict – Aids Homeostasis – Protection • WBC’s Red Blood Cells (Erythrocytes) Blood Cells Erythropoieses (RBC production) LOW O2 Levels Liver and Kidneys create & release Erythropoietin Increased RBC = Increased O2 levels Bone marrow increases RBC production White Blood Cells (Leukocytes) Platelets (Thrombocytes) • Cell fragments • Help close breaks in damaged vessels • Formed from exploded megakarocytes Blood Plasma Hemostasis Clotting Factors Factors of Coagulation • Prevent Coagulation: – Increase circulation – Decrease clotting factors – Medication – Heparin • Promote Coagulation: – Slow circulation/stagnant blood – Damaged Vessel – Medication Antigen on RBC surface Antibody in blood stream RH Blood Groups • Rh Factor • Additional ID marker found on the red blood cell membrane. • If the ID is present = Positive (+) • If the ID is absent = Negative (-) • This factor is not that important until the female becomes pregnant. Agglutination Reactions Thank goodness!!!