The Heart FUN FACTS Center of the circulatory system Beats over 100,000x/day Pumps 1835 gallons/day Study of the heart and accompanying diseases cardiology Heart lies within the mediastinum Center of chest 2/3 lies to the left of the mediastinum Pericardium Prevents overdistension of the heart Anchors heart within mediastinum Three layers to the heart 1.Epicardium: outer layer 2.Myocardium: middle layer made up of cardiac muscle 3.Endocardium: inner lining of the heart, covers valves and the tendons that hold valves open What is??? Epicarditis Myocarditis Endocarditis Four Chambers 2 atria (singular is atrium): holding chambers of heart 2 ventricles: pump blood out of heart to body Blood Vessels Superior vena cava: brings oxygen-poor blood to heart from upper portions of body. Inferior vena cava: brings oxygen-poor blood to heart from lower portions of body Right and left pulmonary arteries: brings oxygen-poor blood from heart to lungs Right and left pulmonary veins: brings oxygenated blood from lungs back to heart Question??? How are pulmonary arteries and pulmonary veins different from all other arteries and veins in your body? Valves Atrioventricular (AV) valves or cuspid valves: between atria and ventricles Tricuspid: on right side of heart Bicuspid: on left side of heart Semilunar valves: between ventricles and arteries leaving heart Pulmonary semilunar valve Aortic semilunar valve Circulatory Problems Ischemia: reduced oxygen. Weakens but does not kill heart cells Angina pectoralis: chest pain due to ischemia Causes: Stress Over exertion Artherosclerosis Fever anemia Myocardial Infarction Heart attack Infarction: death of tissue due to interrupted heart flow Conduction System Your heart is innervated by the autonomic nervous system, but only to regulate speed of contractions Heart has an internal conduction system Sinoatrial Node (SA node): special heart tissue that causes heart to contract A Cut To The Heart SA node Called the pacemaker Self excitation about 75 times/minute Located in the right atrial wall just below superior vena cava opening Initiates excitationspreads to both atria. Causes them to contract After spreading to atria AV node and bundle of His distribute impulse to ventricles via Purkinje fibers Blood Vessels The 3 major types of vessels Arteries carry blood away from the heart Veins carry blood toward the heart Capillaries contact tissue cells (Serving cellular needs) Capillaries Very narrow (10 m diameter, the red blood cells that travel through capillaries are 6 m in diameter). Blood Functions TransportsTransports Dissolved gasses Nutrients Waste products to lungs and kidneys Enzymes Hormones from endocrine organs Functions RegulatesRegulates pHpH Electrolyte concentration of body fluidsElectrolyte concentration of body fluids Body temperatureBody temperature Restricts fluid lossRestricts fluid loss Defends pathogens and toxinsDefends pathogens and toxins Components Blood is the bodys only fluid tissueBlood is the bodys only fluid tissue It is composed of liquid plasma and formed elementsIt is composed of liquid plasma and formed elements Plasma (55%)Plasma (55%) 90% water minerals, sugars, lipids, hormones, proteins (fibrinogen, and albumen) Formed elements (45%) include:Formed elements (45%) include: Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets Physical Characteristics and Volume Blood is a sticky, opaque fluid with a metallic tasteBlood is a sticky, opaque fluid with a metallic taste Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor)Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor) The pH of blood is 7.357.45The pH of blood is 7.357.45 Blood accounts for approximately 8% of body weightBlood accounts for approximately 8% of body weight Average volume of blood is 56 L for males, and 45 L for femalesAverage volume of blood is 56 L for males, and 45 L for females Blood maintains: Appropriate body temperature by absorbing and distributing heatAppropriate body temperature by absorbing and distributing heat Normal pH in body tissues using buffer systemsNormal pH in body tissues using buffer systems Adequate fluid volume in the circulatory systemAdequate fluid volume in the circulatory system Protection Blood prevents blood loss by:Blood prevents blood loss by: Activating plasma proteins and platelets Initiating clot formation when a vessel is broken Blood prevents infection by:Blood prevents infection by: Synthesizing and utilizing antibodies Activating complement proteins Activating WBCs to defend the body against foreign invaders Erythrocytes (RBCs) Erythrocytes Biconcave discs & anucleate allow for a huge surface area to volume ratioBiconcave discs & anucleate allow for a huge surface area to volume ratio Hematocrit percentage of RBCs out of the total blood volume. (Ave) 46 adult men & 42 adult women.Hematocrit percentage of RBCs out of the total blood volume. (Ave) 46 adult men & 42 adult women. There are roughly 5 million RBCs in each microliter of blood; they transport oxygen and carbon dioxide, and have large surface- to volume ratios.There are roughly 5 million RBCs in each microliter of blood; they transport oxygen and carbon dioxide, and have large surface- to volume ratios. Red blood cells account for slightly less than half the blood volume.Red blood cells account for slightly less than half the blood volume. Erythrocytes Erythrocytes are unable to perform normal maintenance operations and usually degenerate after about 120 days in the circulation.Erythrocytes are unable to perform normal maintenance operations and usually degenerate after about 120 days in the circulation. Each red blood cell contains molecules of hemoglobin (Hgb), which can reversibly bind oxygen.Each red blood cell contains molecules of hemoglobin (Hgb), which can reversibly bind oxygen. Leucocytes (White Blood Cells) NucleiNuclei No hemoglobinNo hemoglobin Functions:Functions: leucocytes are phagocytic - What does that mean? effective against bacteria, viruses, fungi, transplanted cells and cancer cells