Learning Objectives... To understand the stages of the cardiac cycle. To be able to label the different parts of the heart.

Heart pictures and information

The Heart The heart is a double pump – two separate pumps that work side by side The right side pumps deoxygenated blood to the lungs The left side pumps oxygenated blood to the rest of the body The heart consists of four chambers –two upper atria and two lower ventricles The atrio- ventricular valves separate the atria and ventricles The semi-lunar valves are found in the pulmonary artery and aorta.

The cardiac cycle How blood flows through the heart Two phases systole – contraction phase (atrial and ventricular) – 0.3 secs diastole – relaxation phase – 0.5 secs DIASTOLE atria fill with blood pressure rises atrioventricular valves open blood passes by gravity into ventricles semi lunar valves closed SYSTOLE Atrial systole Atria contract Forces remaining blood into ventricles Ventricles remain relaxed Ventricular systole Ventricles contract at same time Blood pressure increases AV valves forced shut (so no backflow) Semi-lunar valves forced open Blood pushed into aorta and pulmonary artery

Part I Cardiovascular system Briefly describe, in order, the events during the cardiac cycle in the diagrams below. 1. Diastole……………………………………… ……………………………………………………….. ………………………………………………………… 2. Atrial Systole…………………….……… ……………………………………………………….. ………………………………………………………… 3. Ventricular Systole…………………… ……………………………………………………….. …………………………………………………………