Chapter 12: Heart

Functions of the Heart Generating blood pressure Routing blood Ensuring one-way blood flow Regulating blood supply Functions of the Heart

Size, Form, Location of Heart Mediastinum (divides thoracic cavity) Surrounded by pericardial sac Pericardial fluid reduces friction as heart moves Anchors heart Slightly larger than a closed fist Size, Form, Location of Heart

Two different Pumps Right atrium & ventricle Left atrium & ventricle Blood is pumped TO the lungs and back to heart Blood is pumped TO the body and back to heart Two different Pumps

Two Circuits Pulmonary circuit To and from the lungs “pulmonary” – of or relating to lungs Systemic circuit To and from the rest of the body Two Circuits Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Two pumps and two circuits Two Sets of Pumping Chambers in Heart Right atrium Receives systemic blood Right ventricle Pumps blood to lungs (pulmonary) Left atrium Receives pulmonary blood from lungs Left ventricle Pumps blood to organ systems (systemic) Two pumps and two circuits Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Three Kinds of Blood Vessels Arteries Carry blood Away from heart and carry it to the capillaries Capillaries Microscopic vessels where exchange between cells and blood takes place Veins Receive blood from capillaries and carry it back to the heart Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Coronary Vessels Left and Right coronary arteries from base of aorta Blood from coronary arteries gives up 70% of its blood to heart muscle Coronary Vessels

A separation of the atria from ventricles, on surface of heart; “ditch” Coronary Sulcus

Coronary Thrombosus Thrombosus = “blood clot” A blood clot of the coronary blood vessels Also called “heart attack” Lack of oxygen to tissue Tissue dies Dead tissue = “Infarct” Aspirin: reduces clumping action of platelets Some enzymes can break down blood clots Coronary Thrombosus

Artherosclerotic Lesions Thickening in the wall of the artery Can contain cholesterol/lipid deposits Restrict blood flow Fatigue, pain symptoms (angina pectoris) Artherosclerotic Lesions

Atria & Ventricles Atria: receive blood from veins Reservoir for blood Ventricles: major pumping chambers Interventricular septum: separates the two ventricles Atria & Ventricles

Pericardium Layers Epicardium (Visceral pericardium) Myocardium Simple squamous epithelium Myocardium Cardiac muscle Endocardium Simple squamous Heart contracts due to myocardium Pericardium Layers

Cardiac Muscle Intercalated Disks Reduce electrical resistance between the cells Allows action potentials to pass easily The cells of the atria or ventricles contract at nearly the same time Cardiac Muscle

Action Potential Resting potential -85 mV “Depolarization” Na channel opens Na into cell Ca channels open Ca into the cell Action Potential

Action Potential “Repolarization” Na channels close Na stops K+ moves out Action Potential

“Plateau” Ca channels open Ca into cell Action Potential

Action Potential “Final repolarization” Ca close K+ open and out of cell Returns to resting potential Action Potential

Conduction System of the Heart Sinoatrial Node: pacemaker of the heart Produces action potentials at a faster rate than other areas of heart ----- Meeting Notes (3/4/16 08:17) ----- Know the location of His bundle, location of nodes, location of Perkinje Fibers Conduction System of the Heart

Purkinje fibers: His bundle:

Cardiac Cycle refers to a complete heartbeat from its generation to the beginning of the next beat. It includes the diastole, systole and pause. The repetitive pumping process that begins with cardiac muscle contraction and ends with the beginning of the next contraction. Cardiac Cycle

Cardiac Cycle 1. Ventricular systole: contraction of the ventricle Atrioventricular (AV) valves close (first heart sound – LUBB) Semi-lunar valves open and blood is ejected into pulmonary trunk and aorta 2. Ventricular diastole: ventricles relax Semi-lunar valves close(second heart sound – DUPP) AV valves opens 3. Atrial systole (at end of ventricular diastole): atria contract Forces blood into ventricle so they finish filling https://www.youtube.com/watch?v=-4kGMI-qQ3I Great video on lub-dub Cardiac Cycle

Arrhythmia: abnormal heart rhythm EKG records the electrical activity of the heart P = atria contracting QRS = ventricular depolarization/contraction PR interval = time for SA node to reach ventricles T= ventricular relaxation/repolarization http://www.practicalclinicalskills.com/ekg-practice-drill.aspx Read EKGs Arrhythmia: abnormal heart rhythm

Murmur: abnormal heart sounds Incompetent Valve: doesn’t close all the way, swishing after closure Stenosed Valve: narrowed, swishing before closure

Murmur: abnormal heart sounds Cardiac output: volume of blood pumped each minute (by either ventricle) Stroke volume: volume of blood per ventricle each time heart contracts Heart rate: number of times the heart contracts each minute

ABI: ankle brachial index Blood pressure: systolic (blood pressure as heart contracts) and diastolic (pressure during interval between heartbeats) Evaluates circulation in your leg Shoes and socks removed Uses Doppler Ultrasound to assess blood flow through vessels of arm and ankle ABI: ankle brachial index