1. How the Heart Works. Electrical activity in the heart.

2. Blood flow through the heart http://www.youtube.com/watch?v=Ww2OAsAUIT0

3. 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 Heat Beats Step 1: Enter Atrium

4. Heat 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

5. Heat Beats Step 3: Contract Ventricle Right Side Right ventricle contracts Blood flows through the pulmonary valve into the pulmonary arteries Blood flows towards the lungs Left Side Left ventricle contracts Blood flows through the aortic valve into the aorta (largest artery) Blood flows out towards the body

6. 2 parts of the heart beat Two parts of Heart Beat – LUB: closure of the AV valves (beginning of ventricular contraction - systole) – DUB: closure of the pulmonary & cardiac valves (end of ventricular systole – diastole)

7. Electrical structures of the heart

8. Electrical activity through the heart Starts from SA node in the Right Atrium (top R) Causes Atria to contract (ventricles fill with blood) Impulse sent to the AV node (bottom R of RA) Impulse travels down bundle branches & Purkinje fibres Ventricles contract!

9. Electrocardiogram - ECG P wave: SA node fires and the atria contract QRS complex: AV node stimulates the ventricles to contract (AV valves close) T wave: ventricles relax (the pulmonary valve and aortic valve close)

10. Normal sinus rhythm ECG is used to measure: - heart rate & regularity of heartbeats - the size and position of the chambers - any damage to the heart - the effects of drugs or devices used to regulate the heart

11. Atrial Fibrillation Visible: lack of P wave Cause: hypertension Result: chest pain, heart palpitations, fainting, heart failure, higher risk of stroke Treatment: blood thinners, medication to slow heart rate

12. Ventricular Fibrillation Visible: no clear rhythm Cause: heart attack Result: chest pain, NO heart beat Treatment: defibrillation (Shock)

13. AV Block Visible: delay between S wave & P wave Cause: many... decrease O 2 in blood Result: depends on severity Treatment: pacemaker

14. Asystole Visible: no waves Cause: lack of electrical activity Result: no blood flow, no contractions Treatment: none