The Heart

The Heart2/3 of the mass lies to the left of the bodys midlineThe apex lies on the diaphragm

LocationAnatomy of the HeartPericardium: 2 layered sac surrounding the heart

Myocardium: muscle tissue making up the walls of the chambersEndocardium: smooth lining of heart chambers

The Heart Tissues

Atria: receiving chambersThin walled do to minimal work loadMost work is done by gravityVentricles: discharging chambersMore muscular

The Heart Chambers

The Tricuspid ValveRight Heart3 flaps

The Mitral or Bicuspid ValveLeft heart2 flapsThe AV Valves

Pulmonary Semilunar Valve: at the beginning of the pulmonary artery

Aortic Semilunar Valve: at the beginning of the aortaThe Semilunar Valves

Heart ActionSystole: ContracionDiastole: RelaxationBodyVena CavaRight AtriumTricuspid ValveRight VentriclePulmonary Semilunar ValvePulmonary ArteryLungs

The Action of the Right HeartLungsPulmonary VeinLeft AtriumMitral ValveLeft VentricleAortic Semilunar ValveAortaBodyThe Action of the Left HeartCoronary CirculationBlood which supplies oxygen and nutrients to the myocardium of the hear, flows through the right and left coronary arteries. SA (sinoatrial) Node: the pacemakerGenerator of heart rhythmFound in the right atriumInitiates the electrical sequenceStarts contraction of the atria

AV (atrioventricular) Node: triggers contraction of the ventricles via perjunkie fibers and bundle of His

Ventricles contract from the bottom upwards.This makes sense because the outlets for the blood flow are at the top.

Conduction System http://www.youtube.com/watch?v=v3b-YhZmQu8

An electrocardiogram (ECG or EKG) is a graphical recording of the electrical events occurring within the heart.

A normal ECG has 3 deflections:P Wave: Atrial Systole (initiated by SA Node)QRS Complex: Ventricular SystoleT Wave: Ventricular DiastoleNote: Atrial Diastole is masked by ventricular systoleElectrocardiogram (ECG)A long interval reveals that an impulse has been slowed or has taken a longer route. A short interval reflects an impulse which followed a shorter route. If a complex is absent, the electrical Impulse did not rise normally, or was blocked at that part of the heart. Lack of normal depolarization of the atria leads to an absent P wave. An absent QRS complex after a normal P wave indicates the electrical impulse was blocked before it reached the ventricles. Abnormally shaped complexes result from abnormal spread of the impulse through the muscle tissue, such as in myocardial infarction where the impulse cannot follow its normal pathway because of tissue death or injury.

Note: Electrical patterns may also be changed by metabolicabnormalities and by various medicines.

Things to look for in an ECG: