functioning of the heart Flashcards
how does the heart work
contraction and relaxation of the heart muscles
what is contraction called
systole
what is relaxation called
diastole
how many phases does each heart beat or cardiac cycle take
three phases
name the three phases of the cardiac cycle
atrial systole, ventricular systole ,general diastole
what is a Sino-atrial node
a small patch of special tissue in the right atuim
what is the function of Sino- atrial node
it sends electrical impulses to the muscle fiber of both left and right atria
explain the atrial systole
- sino-atrial node sends electrical pulses to the muscle fiber of both left and right atria
2.atria contracts at the same time
3.tricuspid and bicuspid valves open
4.the blood flows into the two ventricles which are relaxed
5.the phase is 0,1seconds
explain the ventricular systole
- two ventricles contract at the same time
- the blood if forced into the aorta and pulmonary artery
- the tricuspid and bicuspd valves close
- this prevents blood from flowing back into the atria
- this phase lasts 0,3 sec
explain the general diastole
- both the atria and the ventricle relax
- semi-lunar valves and the pulmonary artery close
- this prevents blood from flowing back into ventricals from the aorta and pulmonary artery
- blood enters the atria through the superior and inferior vena cava , and the pulmonary veins and then flow into the ventricles
- this phase lasts 0,4 sec
electrocardiograph
pattern of heart beats produced on paper
what do docters use ecg for
to determine whether the heart is functioning normal or not
lub-dub
the sound you hear is made by the two types of valves snapping shut at different times
(lub)
is made when the blood is forced up against the bicuspid and tricuspid valves causing them to snap shut during ventricular systole
(dub)
the second sound is made when the semi -lunar valves close as blood falls onto them during the general diastole
