Heart Anatomy
(1) Cardiac Tissue Pericardium = Membrane which encloses the entire heart. Secretes a lubricant called Serous Fluid to reduce friction against heart. Outermost Layer = The Epicardium Middle Layer = Myocardium (contains contractile muscle fibers) Innermost Layer = Endocardium (lines the chambers)
(2) The Chambers Heart has 4 chambers. Superior / Top Chambers = Atria 1 on the left, 1 on the right. Primary receiving chambers. Inferior / Bottom Chambers = Ventricles Pumping / Contracting chambers. The right and left chambers are separated by the Septum.
(3) The Veins Vein = A Blood Vessel that carries blood INTO / TOWARD the heart. Your heart has 2 main sets of veins: Superior-Inferior Vena Cava = Carries blood into the right atrium. Pulmonary Veins = Carry blood into the left atrium.
(4) The Arteries Artery = A Blood Vessel that carries blood AWAY / OUT of the heart. Your heart has 2 main arteries: Pulmonary Artery = Carries blood out of the right ventricle. Aorta = Carries blood out of the left ventricle.
(5) The Valves Valves are used to maintain blood flow in 1 direction, and maintain blood pressure. Heart has 4 main valves. AV (Atrioventricular) Valves: Valves between the atria and ventricles. Tricuspid Valve = Between the right atrium and ventricle. Bicuspid (Mitral) Valve = Between the left atrium and ventricle. Semilunar Valves: Valves between the ventricles and exiting arteries. Pulmonary Semilunar Valve = Exits out the Pulmonary Artery. Aortic Semilunar Valve = Exits out the Aorta
(6) The Pulmonary Circuit Carries deoxygenated blood through the right side of the heart, and to the lungs. Path: S/I Vena Cava Right Atrium Tricuspid Valve Right Ventricle Pulmonary Semilunar Valve Pulmonary Artery
(7) The Systemic Circuit Carries oxygenated blood from the lungs, through the left side of the heart, and out to working muscles. Path: Pulmonary Veins Left Atrium Bicuspid Valve Left Ventricle Aortic Semilunar Valve Aorta
The Cardiac Conduction Cycle
(1) What Is The Cardiac Conduction System? The mechanisms behind making your heart beat and pump blood. All mechanisms are involuntary and controlled by the autonomic nervous system. Heart Rate increases or decreases depending on the body’s interpreted need for oxygen.
(2) Depolarization of the Heart Nerve Cells are naturally polarized. Depolarizing a nerve cell, allows it to send a “message” to and from your brain. Nerve “messages” control your heart beat. Path: Nerve Impulse sent from the SA Node to the AV Node in the heart. Slight atrial vibration. Nerve Impulse sent to the AV Bundle. Strong Ventricle contraction. Blood ejected out of the arteries.
(3) The SA & AV Node Node = An intersection of nerves The SA Node: Sinoatrial Node In the right atrium The “Pacemaker” of the heart Starts each heart beat and sets heart rate. The AV Node: Atrioventricular Node Near the left atrium
(4) The Cardiac Cycle While the heart muscle is being depolarized, it is also properly filling with and ejecting blood. This Cycle Happens in 2 Phases: Diastole Systole
(5) Diastole Relaxation of the heart. During this the: AV Valves are open. Semilunar Valves are closed. Blood flows into the atria, and down into the ventricles At the very end of Diastole there is a very slight vibration in the atria, causing the remaining blood to drop down into the ventricles.
(6) Systole Contraction of the heart. During this the: AV Valves are closed. Semilunar Valves are open. Blood is ejected out of the ventricles.
(7) Heart Beat Heart Beat = Sound of your AV Valves closing, followed by your Semilunar Valves closing. Auditory representation of the 2 phases of the cardiac cycle. When Listening: Should not hear blood flow or disturbance. Noises could represent a clot or block to blood flow.
(8) Blood Pressure Blood always flows HIGH TO LOW pressure. During Systole: (~120) Heart is contracting Forceful Ejection of blood Higher Pressure reading During Diastole: (~80) Heart is relaxed Lower Pressure reading Hypertension = Higher than normal blood pressure Hypotension = Lower than normal blood pressure