The Heart Unit 11

The heart is the pump that keeps blood moving around a closed circuit of blood vessels. It beats over 100,000 times a day. Introduction

I.Location, Size, Position The heart is located between the lungs in the lower Mediastinum – a subdivision of the thoracic cavity The Heart

I.Location, Size, Position 2/3 of the heart is to the left of the mediastinum 1/3 of the heart is to the right of the mediastinum The Heart

I.Location, Size, Position The heart is: -triangular shaped -size of a closed fist -Positioned between sternum and thoracic vertebrae The Heart

II. Apical Pulse Heard at the apex of the heart. Landmark – between 5 th & 6 th rib on a line even with the midpoint of left clavicle The Heart

Apex of heart

III. Heart Chambers A.Atria – “receiving chambers” - two upper chambers (right & left) -Smaller than ventricles -Thinner less muscular walls The Heart

III. Heart Chambers B. Ventricles – “discharging chambers” - two lower chambers (right & left) -Thicker more muscular walls The Heart

IV. Structures of the heart A.Myocardium – cardiac muscle in walls of each heart chamber The Heart

IV. Structures of the heart B. Septum – tissue between atria (interatrial septum) or ventricular (interventricular septum) chambers The Heart

IV. Structures of the heart C. Endocardium – thin inner lining of each chamber The Heart

IV. Structures of the heart D. Pericardium – covering of the heart; made of two layers: Visceral pericardium - inner Parietal pericardium - outer The Heart

IV. Structures of the heart D. Pericardium – pericardial fluid serves as a lubricant to prevent friction between layers The Heart

V. Heart Action The heart is a muscular pumping device Systole – contraction of heart Diastole – relaxation of heart The Heart

V. Heart Action The atria contract first pushing blood into the ventricles. Once ventricles fill they contract and push blood out of heart. The Heart

VI. Heart Valves The heart has 4 valves. Two valves separate the atria from the ventricles Atrioventricular Valves (AV) The Heart

VI. Heart Valves Atrioventricular Valves 1.Bicuspid (Mitral) Valve – Located between the left atrium and left ventricle The Heart

VI. Heart Valves Atrioventricular Valves 2. Tricuspid Valve – Located between the right atrium and right ventricle The Heart

VI. Heart Valves Atrioventricular Valves Function of AV Valves – Prevent backflow of blood when ventricles contract The Heart

VI. Heart Valves Two valves separate the ventricles and large arteries. They open and close at the same time. Semilunar Valves The Heart

VI. Heart Valves 1. Pulmonary Semilunar Valve located at the beginning of the pulmonary artery The Heart

VI. Heart Valves 1. Pulmonary Semilunar Valve Function – 1. allow blood going to lungs to flow out of right ventricle 2. Prevents backflow of blood in ventricle The Heart

VI. Heart Valves 2. Aortic Semilunar Valve located at the beginning of the aorta The Heart

VI. Heart Valves 2. Aortic Semilunar Valve Function – 1. Allows blood to flow out of left ventricle into aorta 2. Prevents backflow of blood in ventricle The Heart

VI. Heart Valves - Disorders Incompetent Valves – blood leaks back into chamber which it came from due to faulty or incompetent valve The Heart

VI. Heart Valves - Disorders Stenosed Valves – valves are narrower than normal, slowing blood flow from heart chamber The Heart

VI. Heart Valves - Disorders Rheumatic Heart Disease – Streptococcal infection affecting the heart valves. Occurs more often in children and can cause permanent heart damage. The Heart

VI. Heart Valves - Disorders Mitral Valve Prolapse (MVP)– Usually genetic, but can be from infection. Valve flap does not close properly causing leaking. One of every 20 people have MVP. The Heart

VI. Heart Valves - Disorders Heart Murmurs are abnormal heart sounds caused by abnormalities in the heart valves The Heart

VI. Heart Valves - Disorders Most damaged heart valves can be repaired surgically and in some cases animal or artificial valves can be used. The Heart

VII. Heart Sounds There are 2 distinct heart sounds in every heart beat “Lub-Dub” The Heart

VII. Heart Sounds The first sound “Lub” is caused by the closure of the AV valves during the systole phase of the ventricles The Heart

VII. Heart Sounds The second sound “Dub” is caused by the closure of the semilunar valves during the diastole phase of the ventricles The Heart

VIII. Blood Flow Through Heart The heart acts as 2 separate Pumps: Right Atria and Ventricle Left Atria and Ventricle The Heart

VIII. Blood Flow Through Heart 1. Venous blood enters right atrium from superior and inferior vena cava The Heart

VIII. Blood Flow Through Heart 2. Passes from right atrium to right ventricle by way of the tricuspid valve The Heart

VIII. Blood Flow Through Heart 3. Leaves right ventricle by way of semilunar valve into pulmonary artery which takes blood to lungs The Heart

VIII. Blood Flow Through Heart The Pulmonary Artery is the only artery in the body that carries deoxygenated blood The Heart

VIII. Blood Flow Through Heart 4. Blood returns to left atrium via pulmonary vein the blood is oxygenated The Heart

VIII. Blood Flow Through Heart The Pulmonary Vein is the only vein in the body that carries oxygenated blood The Heart

VIII. Blood Flow Through Heart 5. Passes from left atrium to left ventricle by way of the bicuspid (mitral) valve The Heart

VIII. Blood Flow Through Heart 6. Leaves left ventricle by way of aortic semilunar valve into aorta The Heart

VIII. Blood Flow Through Heart 7. The aorta distributes blood to the rest of the body by way of arteries, arterioles, capillaries, venules, veins and back to the heart. The Heart

Heart Blood Circulation Through Body

IX. Conduction System There are four structures that generate impulses causing the atria and ventricles to contract The Heart

IX. Conduction System 1. Sinoatrial Node (also known as the SA node or the “pacemaker”) 2. Atrioventricular Node (AV Node) The Heart

IX. Conduction System 3. AV Bundle of His 4. Purkinje Fibers The Heart

IX. Conduction System Order of Conduction 1. SA Node - (atria) 2. AV node - (atria) 3. Bundle of His (ventricles) 4. Purkinje Fibers (ventricles) The Heart

X. Diseases Coronary Heart Disease Myocardial Infarction – “Heart Attack” – vessel in heart is not being oxygenated normally due to blockage of coronary artery The Heart

X. Diseases Coronary Heart Disease Angina Pectoris – chest pain caused by a lack of oxygen to the heart muscle. Treatment - Nitroglycerin The Heart

X. Diseases Cardiac Arrhythmia Arrhythmia – a heart beat without regular rate or rhythm The Heart

X. Diseases Cardiac Arrhythmia Bradycardia – Pulse rate less than 60 beats/min The Heart

X. Diseases Cardiac Arrhythmia Tachycardia – Pulse rate greater than 100 beats/min The Heart

X. Diseases Cardiac Arrhythmia Fibrillation – Heart beating erratically, without any rhythm and not fully contracting, hence blood flow is not adequate – life threatening The Heart

X. Diseases Heart Failure Cardiomyopathy – diseases of the myocardial tissue The Heart

X. Diseases Heart Failure Cor Pulmonale – Right-sided heart failure, usually results from untreated left-sided heart failure The Heart

X. Diseases Heart Failure Congestive Heart Failure – “CHF” Left-sided heart failure, fluid backs up into the lungs because the heart is not able to pump effectively The Heart

XII. Tests For Heart Electrocardiogram – EKG or ECG. A graphic record of the heart’s electrical activity The Heart

XII. Tests For Heart Electrocardiogram Depolarization – Electrical activity triggers contraction of heart muscle The Heart

XII. Tests For Heart Electrocardiogram Repolarization – Begins before relaxation phase of cardiac muscle “recharging” the heart muscle The Heart

XII. Tests For Heart Three normal findings: 1. P-Wave 2. QRS Complex 3. T-Wave The Heart

XII. Tests For Heart Three normal findings: 1. P-Wave depolarization/contraction of atria The Heart

XII. Tests For Heart Three normal findings: 2. QRS Complex depolarization/contraction of ventricles The Heart

XII. Tests For Heart Three normal findings: 3. T-Wave repolarization/relaxation of ventricles The Heart

End of Lecture