The Heart

2/3 of the mass lies to the left of the body’s midline

The apex lies on the diaphragm

Location

Anatomy of the Heart

Pericardium: 2 layered sac surrounding the heart

Myocardium: muscle tissue making up the walls of the chambers

Endocardium: smooth lining of heart chambers

The Heart Tissues

Atria: receiving chambers◦ Thin walled do to minimal work load◦ Most work is done by gravity

Ventricles: discharging chambers◦ More muscular

The Heart Chambers

The Tricuspid Valve◦ Right Heart◦ 3 flaps

The Mitral or Bicuspid Valve◦ Left heart◦ 2 flaps

The AV Valves

Pulmonary Semilunar Valve: at the beginning of the pulmonary artery

Aortic Semilunar Valve: at the beginning of the aorta

The Semilunar Valves

Heart ActionSystole: ContracionDiastole: Relaxation

Body Vena Cava Right Atrium Tricuspid Valve Right Ventricle Pulmonary Semilunar Valve Pulmonary Artery Lungs

The Action of the Right Heart

Lungs Pulmonary Vein Left Atrium Mitral Valve Left Ventricle Aortic Semilunar Valve Aorta Body

The Action of the Left Heart

Coronary Circulation Blood which supplies oxygen and nutrients

to the myocardium of the hear, flows through the right and left coronary arteries.

SA (sinoatrial) Node: the pacemaker Generator of heart rhythm Found in the right atrium Initiates the electrical sequence Starts 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 Systole T Wave: Ventricular Diastole

Note: Atrial Diastole is masked by ventricular systole

Electrocardiogram (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: