What do I remember? What is the structure of the heart? What is the path of blood through the heart? What is the definition of cardiac output? How is cardiac output calculated?

Unit 2 Physiology and Health 2. Cardiac cycle Higher Human Biology Unit 2 Physiology and Health 2. Cardiac cycle

Activity Watch Dr Alice The Heart

What do I need to know? What is the cardiac cycle? What is the difference between systole and diastole? What effect does a change in pressure have on the Atrioventricular valve? What effect does a change in pressure have on the semi lunar valve?

What is the cardiac cycle? The pattern of contraction and relaxation shown by the heart in one complete heartbeat Beating heart with blood flow

What is the difference between systole and diastole? Heart muscle is contracting – Squeezing blood out of the chambers Diastole Heart muscle is relaxing allowing blood to flow back into the chambers

Cardiac cycle in motion

Effect of pressure on AV valve During atrial diastole atria fill with blood Pressure in atria exceeds that in ventricles AV valve opens Blood flows into ventricle Atrial systole follows squeezing remaining blood into ventricles Pressure builds up in ventricles causing AV valves to close Backflow of blood from ventricle to atrium prevented

Effect of pressure on Semi lunar valves Pressure increases in the ventricles Ventricular systole cause semilunar valves to open Blood rushes into pulmonary artery and aorta Blood pressure in arteries increases Semilunar valves close Back flow of blood from artery to ventricle prevented

Lubb dupp Lubb dub are the heart sounds Lubb – when AV valves close Dupp – when semilunar valves close

What do I know? What is the cardiac cycle? What is the difference between systole and diastole? What effect does a change in pressure have on the Atrioventricular valve? What effect does a change in pressure have on the semi lunar valve?

Activities Text book Qs p172 No 1