Biology AQA 3.1.5 Heart Structure and Function

Veins are to the heartArteries are away from the heart.

Left hand side the muscle is thicker:Oxygenated blood from the pulmonary vein,moves from atrium to ventricle over an atrioventricular valveVentricle then pushes it pass semi-lunar valves and through the aorta

Right hand side:deoxygenated blood travels through the vena cavait then passes over the av valves into the ventricles and then is pumped through the semilunar valves and through the pulmonary artery

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Atrium Systole (relaxing)Volume low in ventricle, but some is moving into. High pressure in atrium low in ventricle.Atrium Diastole (contracting)Volume increases in ventricles and decreases in atrium. The pressure increases in ventricles.Ventricle Diastole (contracting)Aorta pressure increases, and pressure decreases in ventricles as well as tidal volume.

Pressure is higher in the Aorta compared to pulmondary artery

so

so left muscle is thicker so that blood can be pushed through the aorta

the cross over of aorta and ventricle shows opening of semi-lunar valves

The crossing over of the atrium and ventricle shows opening of atrioventricular valves

Pressure increases when blood enters

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Myogenic stimulation of the heart (Contractions of the heart using nerves.)

The sinoatrial node (SAN) works as a pace maker for the heart, and sends electrical impulses to the atrium causing them to contract, this impulse is then stopped by muscle fibres.After a short delay, The Atrioventricular node (AVN) sends electrical impulses down the bundle of His to the apex of the heart. This causes the ventricles to contract from base upwards.

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Cardiac output = heart rate x stroke volume

heart rate= Cardiac output                    ---------------------                    stroke volume

Stroke volume= Cardiac output                             ---------------------                              Heart rate

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