Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
3 Cards in this Set
- Front
- Back
|
Ventricular diastole
|
¯ 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 |
|
|
Atrial systole
|
¯ 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 |
|
|
Ventricular Systole
|
- 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 |
