chapters 16 & 17 the heart

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Chapters 16 & 17 The Heart. Joe Pistack MS/ED. Heart. The heart is a hollow muscular organ about the size of a closed fist Sits inside the chest within the mediastinum, between the lungs Lies toward the left side of the body Supported by the pericardium (slinglike structure). Heart . - PowerPoint PPT Presentation

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Heart

Chapters 16 & 17The HeartJoe Pistack MS/EDHeartThe heart is a hollow muscular organ about the size of a closed fist

Sits inside the chest within the mediastinum, between the lungs

Lies toward the left side of the body

Supported by the pericardium (slinglike structure)

22/3 are left of midline & 1/3 is located to the rightPericardium is sling like structure that supports the heart

Heart Function of the heart is to pump blood through the blood vessels of the body, providing oxygen & nutrients to all cells

The heart pumps on average 72 times/minuteInteresting Facts:About 104,000 beats per day2 ounces per beatCirculates almost entire blood volume every minute2000 gallons a dayThats about 40- 55 gallon drums every dayOver 1 million beats every 10 daysAlmost 38 million beats every yearLayers of the HeartHeart is made up of 3 layers:Endocardium: It is the innermost layer and is composed of a thin layer of simple squamous epithelium over a layer of connective tissueSmooth and shiny surface allows blood to flow easilyLines valves & vessels entering & leaving heartSeamless so there is no place to stickLayers of the HeartMyocardium:Thick middle layerThickest of all layers composed of cardiac muscle tissue Allows the heart to contract, propelling blood through blood vesselsEpicardium: Thin outermost layerContinuous at apex with the inner lining of the pericardiumHeartPericardium:Sling like structure that supports the heart & attaches the heart to sternum & diaphragmPericardial space: serous membrane located between the epicardium & pericardium serous membrane secretes serous fluid (pericardial fluid) that lubricates the surfaces of the membranes allowing them to slide past one another without rubbing or friction8When the pericardial space become inflammed or secretes too much serous fluid it impinges on the hearts ability to pump; cardiac tamponadeNeed to insert needle to relieve fluid & pressureHeartTwo pumps and two circulations:The pumps are the:left side of the heartright side of the heartThe two circulations are:pulmonary circulationsystemic circulationCirculationThe right side of the heart:Receives deoxygenated blood from the superior and inferior vena cavaPumps blood to the lungs where the blood is oxygenatedThe blood travels from the right side of the heart to the lungs then back to the left side of the heartThis path is called pulmonary circulationOnly function of pulmonary circulation is to circulate the blood to the lungs for oxygen & to rid the body of carbon dioxide10Superior & inferior receives blood from all parts of bodyCirculationThe left side of the heart:Receives the oxygenated blood from the lungs and pumps out the aorta to all the organs of the bodyThe path the blood takes from the left side of the heart to the organs of the body and then back to the right side of the heart is called systemic circulationPulmonary & Systemic Circulations

Chambers of HeartHeart has 4 chambers:2 atria and 2 ventriclesThe atria:Right and Left Upper chambers of heartReceive bloodThe ventricles:Right and Left Lower chambers of heartPump blood out of heartChambers of HeartRight and Left heart are separated by septumInteratrial septum separates atriaInterventricular septum separates ventricles

Chambers & VesselsRight atrium:Is thin-walled cavity Receives deoxygenated blood from large veinsSuperior vena cava collects blood from the heart and upper body regionInferior vena cava receives blood from the lower part of the bodyChambers & Vessels Right Ventricle:

Receives deoxygenated blood from the right atrium

Pumps blood to lungs through the pulmonary artery

Main function of right ventricle is to pump blood to the lungs

17Only arteries to carry unoxygenated blood in the body Chambers & VesselsLeft Atrium:Thin walled cavity Receives oxygenated blood from the lungs through the 4 pulmonary veins18Only veins to carry oxygenated blood in our body

Chambers & VesselsLeft Ventricle:Receives oxygenated blood from the left atriumPrimary function is to pump blood into systemic circulationBlood leaves the left ventricle through the aortaThick walled cavity needed to generate enough force to pump the blood out of the heart into systemic circulation19Aorta is largest artery in the bodyHeart ValvesThe purpose of heart valves is to keep the blood flowing in a forward direction4 valves2 valves are located between the atria and ventricles are called atrioventricular valves or AV valves - called entrance valves2 other valves are called semilunar valves which are considered exit valves20Entrance valves because the blood enters the ventricles from the atriaExit because the blood is exiting the heart; either to the aorta & systemic circulation or to the lungs or pulmonic circulation

Heart valvesAtrioventricular Valves:Located between the atria and ventricle on each side to the heartHave cusps or flapsWhen ventricles are relaxed, cusps fall away from the atria allowing valves to open permitting blood flow from atria to ventriclesWhen the ventricles contract, the heart muscle squeezes the blood in the ventricles, pushing the cusps upward toward the atria into a closed positionThe AV valves prevent backward blood flow from the ventricles into the atriaHeart ValvesCusp are attached to the ventricular wall by tough fibrous bands called chordae tendineaeAs blood pushes the cusps into a closed position, the chordae tendineae are stretched to full length The stretched chordae tendineae hold onto the cusps and prevent them from being pushed backward into the atriaHeart ValvesRight Atrioventricular Valve:Called the tricuspid valve because it has 3 cuspsLocated between the right atria & right ventricleWhen the tricuspid valve opens, blood flows freely from the right atrium into the right ventricleWhen the right ventricle contracts, the tricuspid valve closes preventing the blood from flowing back into the right atrium

Heart ValvesLeft atrioventricular Valve:Called the bicuspid valve because it has 2 cuspsIt is also called the mitral valveLocated between the left atrium and left ventricleWhen the mitral/bicuspid valve is open, blood flows from the left atrium into the left ventricleWhen the left ventricle contracts, the mitral/bicuspid valve closes preventing the backflow of blood into the left atrium

Heart ValvesSemilunar Valves:Considered exit valves2 types:Pulmonic valveAortic valve

26Heart ValvesPulmonic Valve:Also called right semilunar valveLocated between the right ventricle & the pulmonary arteryWhen the right ventricle relaxes, the valve is in a closed positionWhen the right ventricle contracts, blood from the ventricle forces the pulmonic valve openBlood then flows through the open valve into the pulmonary artery & into the lungs

Heart ValvesAortic Valve:Also called left semilunar valveLocated between the left ventricle & aortaWhen the left ventricle relaxes, the valve is in a closed positionWhen the left ventricle contracts, blood from the ventricle forces the aortic valve to openBlood flows through the aortic valve into the aortaWhen the left ventricle relaxes, the aortic valve snaps closed preventing backflow from the aorta into the ventricleHeart ValvesSemilunar Valves close when the pressure in the pulmonic artery & aorta become greater than the pressure in the ventriclesBlood from great vessels gets behind the valves & snaps them closedThe closed semilunar valves prevent the backward flow of blood from the pulmonary artery & aorta into the ventricles

31Significant for listening to heart sounds; listen for normal closure of valves; pick up on path of valves such as murmurs at the specific location of the valve being evaluatedHeart SoundsVibrations caused by the closure of the valves are heart soundsThe first heart sound, lubb, is due to the closure of the AV valves at the beginning of ventricular contractionThe second heart sound, dupp, is due to the closure of the semilunar valves at the beginning of ventricular relaxationMurmurs are abnormal heart sounds due to pathology of valvesPathway of BloodUnoxygenated blood enters the right atrium from the superior & inferior vena caveRight AtriumTricuspid ValveRight VentriclePulmonic Valve

Pathway of BloodPulmonary artery (right & left)Pulmonic circulation/Lungs4 Pulmonary Veins Left Atrium

34Right & left pulmonary artery into pulmonary circulationLungs for gas exchangePathway of BloodBicuspid/ Mitral ValveLeft VentricleAortic ValveAorta Systemic CirculationMyocardium Blood Supply The myocardium of the heart receives its blood supply from the coronary arteries Coronary arteries arise from the aorta just above the aortic valveTwo main arteries are:Left & Right coronary arteryCoronary ArteriesRight coronary artery nourishes the right side of the heart, esp. Right ventricleLeft coronary artery branches into the left anterior descending artery Coronary veins collect blood that nourishes the myocardium and carries it to the coronary sinus which empties into the right atrium37If coronary arteries blood flow is interrupted, myocardium is damaged, cell death occurs. Called MI or heart attack

Cardiac Conduction SystemAn electrical signal stimulates the heart muscle to contract and coordinates the pumping activity of the atria and ventriclesBoth atria contract at same time followed by simultaneous contraction of both ventriclesThe conduction system is located in the walls of the heart and in the septum that separates the right and left sides of the heart

Cardiac Conduction SystemConduction System consists of:Sinoatrial nodeAtrial conducting fibersAtrioventricular nodeBundle of His which branches left and rightPurkinje SystemCardiac Conduction SystemSinoatrial Node:Pacemaker of the heartLocated in the up