The Heart

Katie Kenney
Mind Map by Katie Kenney, updated more than 1 year ago
Katie Kenney
Created by Katie Kenney about 5 years ago
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AS LEVEL Biology Mind Map on The Heart, created by Katie Kenney on 01/02/2015.
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The Heart
1 The Cardiac Cycle
1.1 Atrial Systole - ventricles are relaxed, atria fill with blood decreasing the volume and increasing the pressure forcing the atrioventricular valves to open, allowing blood to flow into ventricles.
1.2 Ventricular Systole - ventricles contract and atria relax, pressure is higher in ventricles than in atria so the AV valves close to prevent backflow, high pressure in ventricles opens semilunar valves forcing blood out into the pulmonary artery and aorta
1.3 Diastole - atria and ventricles both relax increasing the volume and lowering the pressure, the higher pressure in pumonary artery and aorta forces the semi lunar valves to closepreventing backflow, the atria fill with blood again due to the high pressure in the vena cava and pulmonary vein
2 cardiac muscle is MYOGENIC - it can contract and relax without receiving signals from nerves
3 Controlling a Regular Heartbeat
3.1 process starts in the sino atrial node in the wall of the right atrium
3.1.1 the SAN sends out regular waves of electrical activity to the atrial walls causing the right and left atria to contract at the same time
3.1.1.1 a band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles
3.1.1.1.1 instead, the waves are transferred from the SAN to the atrioventricular node. the AVN passes the waves onto the bundle of His, but theres a slight delay before the AVN reacts to make sure the ventricles contract after the atria have emptied
3.1.1.1.1.1 the bundle of His conducts the waves to the Purkyne tissue, which carries the waves into the walls of the right and left ventricles causing them to contract simultaneously from the bottom upwards
4 Electrocardiograph
4.1 P wave - contraction of atria QRS complex - contraction of ventricles T wave - relaxation of ventricles
4.2 Heart Problems
4.2.1 Trachycardia - fast heartbeat (around 120 beats per min), if at rest heart won't be pumping blood out efficiently
4.2.2 problem with AVN - impulses aren't travelling from the atria through to the ventricles
4.2.3 Fibrillation - really irregular heartbeat, heart loses it's rhythm and stops contracting properly, can lead to death
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