Heart as a pump Flashcards
what is the cardiac cycle and what does it refer to
it refers to the contractions and relaxation of the heart muscles (heartbeat)
what is the sound of the heart beat na what is the reason for the sound
lub dub
it is the closing of the valves as the atrial and ventricular muscles contract
what does the waal of the right atrium have
its has a group of specialised cells known as the Sino-atrial node which acts as a pacemaker
what dos the SA node determine
it determine the rate of contraction of the atria and the ventricles and acts acc to the needs of the body and co ordinates the contraction of the heart muscle cells
how many phases are associated with each heartbeat /cardiac cycle
3 phases
name the three phases
atrial systole
ventricular systole
atrial and ventricular diastole
how long does each cycle last
0.8 seconds
Explain the events of atrial systole
Muscles of the atria contract.
The tricuspid and bicuspid valves are forced open to allow blood to flow from the atria into the ventricles
What is the duration of atrial systole
Duration: 0.1 seconds
Explain the events of ventricular systole
Muscles of the ventricles contract. Both tricuspid and bicuspid valves close (the lub sound).
Semi-lunar valves of the pulmonary artery and aorta open.
Deoxygenated blood from the right ventricle is forced up the pulmonary artery and moves to the lungs.
Oxygenated blood from the left ventricle is forced up the aorta and moves to all parts of the body.
What is the duration of ventricular systole
Duration: 0.3 seconds
Explain the events of atrial and ventricular diastole
Muscles of the atria and ventricles relax.
Semi-lunar valves in aorta and pulmonary artery close to prevent any back flow of blood (the dub sound).
Deoxygenated blood from the vena cavae fills the right atrium; oxygenated blood from the pulmonary veins fills the left atrium.
The cycle then starts again.
What is the duration of atrial and ventricular diastole
Duration: 0.4 seconds
