The cardiac cycle An overview of the processes of the heart and key words. 2.0 / 5 based on 1 rating ? BiologyHuman, animal and plant physiologyASAQA Created by: Marianne BradleyCreated on: 01-11-10 15:05 Key words and phrases Systole: When the heart muscle contracts Diastole: When the heart muscle relaxes SAN: the SinoAtrial Node (pacemaker). This initiates the heartbeat. AVN: the AtrioVentricular Node Myogenic: a muscle that doesn't fatigue, and that functions without signals from the brain. Cardiac output= heart rate x stroke volume 1 of 4 1. Relaxation of the heart (diastole) The blood enters the atria and ventricles from the pulmonary veins and the vena cava. The atria are relaxed and fill with blood The ventricles are relaxed The semi lunar valves are closed, and the left/right atrioventricular valves are open. The relaxation of the ventricles draws blood into the atria 2 of 4 2. Contraction of the Atria (atrial systole) The atria contract to push the remaining blood into the ventricles. The semi lunar vlaves are still closed. The left and right atrioventricular valves are open. Blood is pumped from the atria to the ventricles. The ventricles remain relaxed 3 of 4 Contraction of the ventricles (Ventricular systole The atria relax. The semi lunar valves open. The atrioventricular valves close. The ventricles contract, pushing blood away from the heart. The blood is pumped into the pulmonary arteries and the aorta. 4 of 4
Comments
No comments have yet been made