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3 Cards in this Set
- Front
- Back
Ventricular diastole
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¯ Heart relaxes (both atria and ventricles)
¯ Blood fills atria from veins (vena cava/pulmonary vein) ¯ High pressure blood in the arteries (aorta/pulmonary artery) but semilunar valves snap shut and prevent backflow into the heart |
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Atrial systole
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¯ Sino-atrial node (SAN/Pacemaker) initiates heartbeat by sending a wave
of electrical activity spreading rapidly over the atrial walls. Cardiac muscle is myogenic (contracts rhythmically on its own) but alter the rhythm to that of the SAN. ¯ Atria contract. ¯ Blood forced trough the AV valves to the ventricles as blood at higher pressure in atria than ventricles |
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Ventricular Systole
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- Excitation wave cannot pass into the ventricular walls
- Atrioventricular node (AVN) delays the impulse, then relays the impulse to the septum between the ventricles - Purkinje Fibres (Purkyne tissue) conduct impulse to the apex of the heart - Ventricles contract from the base upwards - Ventricular pressure higher than aortic pressure - Blood forced through semilunar valves into arteries (aorta/pulmonary artery) - AV valves prevent backflow of blood into the atria |