The HEART Anatomy and Physiology

Introduction Triangular shape Size of your fist Located between the lungs in lower portion of mediastinum behind sternum 2/3 of mass to left of sternum Blunt end is called apex and points toward left Site where heart sounds are best heard

Heart Chambers Organ is hollow Divided into right and left sides Contains four hollow chambers –Atria- top chambers or receiving chambers –Ventricles-lower chambers or discharging chambers Atria are smaller than ventricle Have right and left atria as well as right and left ventricles

Layers of Heart Endocardium- inner most layer of thin smooth tissue Myocardium-middle muscular layer Pericardium-outer layer that consist of two layers of fibrous tissue –Visceral Pericardium or epicardium- inner layer of pericardium –Parietal Pericardium- loose fitting covering on the outside of the heart Epi-upon or onEndo-within or in

Chambers of the Heart

Diseases of Layers Endocarditis-inflammation or infection of inner layer of heart Thrombosis- blood clot –Caused by endocardial lining becoming rough and abrasive to RBC’s passing over its surface. –As blood flows over a rough surface clots are subject to form Embolis-blood clot that is flowing in blood stream Pericarditis-inflammation or infection of pericardium

Diseases of Layers Pericardial Effusion-when pericardial fluid, pus of blood may accumulate in the space between two pericardial layers and impairs the pumping action of the heart Cardiac Tamponade- when pericardial effusion gets worse and develops a serious compression of the heart Myocarditis-infection or inflammation of myocardium

Heart Valves Atrioventricular Valves-separate the atria from the ventricles –Triscupid valve- between right atrium and ventricle –Bicuspid or Mitral valve-between left atrium and ventricle –Prevents backflow of blood into the atria when the ventricles contract –Chordae tendineae-attaches AV valves to the wall of the heart

Atrioventricular Valves

Heart Valves Semilunar Valves-located between the two ventricular chambers and large arteries that carry blood away from the heart –Pulmonary semilunar valve- located between right ventricle and pulmonary artery –Aortic semilunar valve- located between left ventricle and aorta –Both valves prevent backflow of blood into ventricles

Disorders of Valves Incompetent valves-allow some blood to flow back into the chamber from which it came Stenosed Valves- valves that are narrower than normal, slowing blood flow from a heart chamber Mitral Valve Prolapse- (MVP) when the flaps of the Mitral valve extend back into the left atrium, causing incompetent valves

Semilunar Valves

Heart Action Heart is a muscular pumping device Systole- contraction of the heart Diastole relaxation of the heart When heart beats→atria contract first (atria systole)→forcing blood into ventricles Once filled→two ventricles contract (ventricular systole)→blood forced out of heart

Blood Flow Right Side Enters heart through Superior/Inferior Vena Cava –Blood is oxygen poor from the body Goes to Right Atrium Through Tricuspid Valve Into Right Ventricle Through Pulmonary Valve To Pulmonary Artery and into lungs

Blood Flow Left Side From lungs where O2 is added and CO2 removed goes to Left Atrium then through Mitral Valve to the Left Ventricle then through Aortic Valve to the Aorta where it is carried to all parts of the body

Anatomy of Heart

Heart Sounds Heart with stethoscope on anterior wall of chest Rhythmic and repetitive sounds “Lub dub” First sound or lub-caused by vibration and abrupt closure of AV valves as ventricles contract Longer sound with a lower pitch Second sound or dub-caused by closure of semilunar valves during diastole

Heart Sounds Heart Murmurs-abnormal heart sounds caused by disorders of valves Incompetent valves cause a swishing noise as a “lub” or Dup” ends Stenosed valves, often cause swishing sounds just before “lub” or “dup”

Coronary Circulation Heart muscle or myocardium requires on going supply of blood to function Coronary circulation-the delivery of oxygen and nutrient rich arterial blood to the cardiac muscle and removal of oxygen-poor blood from the active tissue to the venous system Blood flows into the heart muscle by way of two small vessels called Right Coronary Artery and Left Coronary Artery

Coronary Circulation

Coronary arteries are the first branches of the aorta Myocardial Infarction or heart attack occurs when one of these arteries are occluded with a blood clot or plaque –Tissue death occurs when area is deprived of oxygen Atherosclerosis- “hardening of the arteries” due to a build up of lips or other substances inside walls of blood vessels

Coronary Diseases Angina Pectoris-Severe chest pain due that occurs when the myocardium is deprived of oxygen –Usually a warning sign that the arteries are no longer able to supply enough blood and Oxygen to the heart muscle Coronary Artery Bypass Graft-Surgery to bypass a damaged or occluded coronary artery

Conduction System Cardiac muscles are coordinated by electrical impulses Has it’s own built in conduction system that is embedded into wall of the heart to generate and conduct impulses Sinoatrial Node- SA Node-sometimes called the “natural Pacemaker” of the heart Atrioventricular Node-AV node- sends impulses from atria to ventricles

Conduction System cardiogram.htmvideo.about.com/heartattacks/Electro cardiogram.htm

Conduction System AV Bundle or Bundle of HIS- sends impulses down middle of ventricles Purkinje Fibers-carries impulses around the outsides of the ventricles Ventricular beats always follows each atria beat If this does not occur then you have Heart Blocks

Conduction System

Normal Electrocardiograph

Cardiac Arrhytmias

Cardiac Arrhythmia Arrhythmia-an abnormal heart rhythm Heart Block-type of arrhythmia where the impulses are blocked from transmitting –AV Node Block-Blocked from getting to the ventricular myocardium –Complete Heart Block-occurs when the P waves do not match up with the QRS as seen on an ECG

Cardiac Arrhythmia Bradycardia- slow heart rate, most often caused by defective SA node Tachycardia-fast heart rate, improper autonomic control of the heart Sinus arrhythmia-variation of heart rate during breathing cycle –Heart rate increases with inspiration and decreases with expiration

Cardiac Arrhythmia Premature Contractions- contractions that occur before the next expected contraction in a series of cardiac cycles –Premature Atrial Contraction- may occur shortly after the ventricles contract –Premature Junctional Contraction-may occur before the AV node fires –Premature Ventricular Contraction-may occur before the Bundle of HIS contracts

Cardiac Arrhythmia Fibrillation-a condition in which cardiac muscle fibers contract out of step with each other –Atrial Fibrillation-common in elderly, can be treated with medications or defrillation –Ventricular Fibrillation- life-threatening condition in which defribillation is a must Flutter-when cardiac fibers flutter instead of contracting

Heart Failure Inability to pump enough returned blood to sustain life Right-sided heart failure-failure of the right side of the heart to pump blood, usually because the left side is not pumping effectively Left-Sided heart failure- Congestive Heart Failure-inability of left ventricle to pump effectively