2. The heart is protected by rib cage locate between two lungs made of cardiac muscle protected by pericardium and rib cage contracts and relaxes continuously to provide (pumping force) The mammalian heart Heart

3. Heart – External View Blood vessel Cardiac Muscle Coronary artery and vein

4. Vertical section of the Heart Left auricle Left ventricle Right auricle Right ventricle bicuspid valve Valve – prevent back flow of blood from ……………… to …………….. Arteries Veins To lungs To body deoxygenated blood oxygenated blood Pulmonary artery Aorta Pulmonary veins Vena cava septum tricuspid valve Semi-lunar valves

5. Oxygenated blood Higher oxygen concentration Lower carbon dioxide concentration Deoxygenated blood Lower oxygen concentration Higher carbon dioxide concentration Full of Oxygen  Full of carbon dioxide 

6. The cardiac cycle The cardiac cycle (the sequence of events that takes place in one heart beat) Auricle Ventricle 0 0.2 0.4 0.6 0.8s The heart beats as the cardiac muscles in its wall contracts (systole) and relaxes (diastole).

7. Auricle Ventricle 0 0.2 0.4 0.6 0.8s  Auricular systole (0 –0.1s) contraction of the two auricles, squeezing blood into the ventricles AV valves (open), semi-lunar valves (close)

8. Auricle Ventricle 0 0.2 0.4 0.6 0.8s  Ventricular systole (0.1 –0.4s) contraction of the two ventricles, forcing blood out of the ventricles into the arteries AV valves (close), semi-lunar valves (open)

9. Auricle Ventricle 0 0.2 0.4 0.6 0.8s  Diastole ( 0.4 - 0.8s ) all four chambers relax, allowing blood to flow into the auricles again. AV valves (open), semi-lunar valves (close)

10. Changes in blood pressure in the heart during one cardiac cycle. bicuspid valve close P(V) < P (A)P(V) > P (A) bicuspid valve open Heart beat rate = 60 / 0.8 = 75 beats / min 1st heat sound

11. Heart attack Fatty substances in blood cover the inner wall of arteries Plaque is formed and the arteries become narrower This reduce the amount of blood flowing Normal artery Artery with fatty deposits Formation of blood clot fatty substances blood flow restricted (artery blocked by blood clot)

12. heart Heart attack Same parts of heart muscle get too little nutrients and oxygen Heart beat is upset HEART ATTACK if coronary artery is blocked damaged heart muscle