The Heart And how it works…

Heart Beats

Heat Beats Step 1: Enter Atrium Right Side Deoxygenated blood enters the right atrium through 2 large veins Superior vena cava: upper half of the body Inferior vena cava: below the diaphragm Left Side Oxygenated blood (from the lungs) enters the left atrium through the pulmonary vein Comes from the lungs

Heart Beats Step 2: Contract Atrium Blood flows from the atrium into the ventricle The atrioventricular (AV) valve allows for a one-directional flow The AV valve closes once the ventricle is full - LUB

Heart Beats Step 3: Contract Ventricle Right ventricle contracts Blood flows through the semilunar valve into the left pulmonary artery – DUB Blood flows towards the lungs Left ventricle contracts Blood flows through the semilunar valve into the right pulmonary artery Blood flows out towards the body

Path of Blood through the Heart

Heart Sounds Two normal heart sounds Other sounds Lub: closure of the AV valves (beginning of ventricular contraction - systole) Dub: closure of the semilunar valves (end of ventricular systole – diastole) Other sounds Heart murmur: turbulent blood flow

Heart Murmur: back flow

Overview: Blood Flow Blood in body Into heart via vena cava (vein) Right atrium Right Ventricle Left pulmonary artery (deoxygenated) Lungs (becomes oxygenated) Pulmonary vein Left atrium Left ventricle Arteries (oxygenated towards body tissue)

Connecting the Heart to the Lungs & the Body

Setting the Heart’s Tempo Heart muscles contract without being stimulated by external nerves (myogenic muscles) Heart muscle does not all contract at the same rhythm when separated Heart rhythm is set by the sinoatrial (SA) node – specialized nerve cells Nerve impulses travel to a second node AV node which sends the message toward the ventricles

Normal Sinus Rhythm P wave followed by a ventricular response

Atrial Fibrilation Most common arrhythmia Result of hypertension

AV Block Delay in the AV node Caused by many things but could be decreased levels of Oxygen in the blood

Ventricular Fibrilation The ventricles are not contracting as a unit There is no clear cardiac output Commonly known as a Heart Attack

Flatline: Asystole: no cardiac electrical activity (no contractions or blood flow) – cannot be treated with defibrillation