week 7 copy

 

Detail step of cardiac cycle

 the cardiac cycle include event happen in heart 

one heartbeat to the next

it repeat over and over 

duration of each cycle can be calculated from the heart rate 

e.g if the heart rate is 72bpm 

the length cycle length would be 1 over the heart rte 

one over 72 is 0.013 and that's in minutes 1/72=0.013

 its very small number 

if we multiply with 60 give us the number in seconds 

which is around 0.8 second for each cardiac cycle . 

If the heart rate is increase the cycle length is shorter 

if the heart rate is decrease the cycle length is longer.

during the time there is both contraction and relaxation of the heart

there is atria systole and atria diastole

atrial systole happen before the ventricle systole 

0.8second atria systole would take 0.1 second 

so the rest cycle is 0.7 second the atria spend in diastole

ventricular systole is longer around 0.3 seconds.

the remaining 0.5 second is in diastole

the number would vary depending on the cycle.

but atrial diastole overlaps 

the rest of the cycle is when both atria and ventricle are relaxing in the diastole 

both chamber the duration of diastole is longer than systole 

what exactly need to happen

between heartbeat 

blood from the body and from the lungs reach to atria

this flow into the ventricle 

the ventricles pump out the blood through pulmonary trunk , aorta to reach the lungs and the rest of the body

Pre class activity 2 overview of cardiac cycle

 cardiac cycle 

The heart rhythmatically send blood around the body

The sequence take place in one heart beat is called cardiac cycle.

each cycle last 0.8 seconds when the person at rest

the cardiac cycle has three stage 

atrial systole 

ventricle systole 

Diastole atria and ventricle relax 

Electrical impulse spread from SA node to atria

https://youtu.be/JEIF5o7Axbg?si=tnj6xnH143LOudN8

The atria pump the blood to ventricle through av valves and bicuspid valve 

The ventricle are relax states and the semilunar valves are close 

in ventricular systole the atria relax mean while the electrical impulse generated from SA node 

reach the ventricle cause them to contract

when ventricle contract the semilunar valve force to open

the blood pump from ventricle to aorta and pulmonary artery

at the same time av valve and mitral valve are close 

the closing of valve produces the first heart sound lub

in diastole both atria and ventricle relax the semilunar valve are close 

to prevent back flow of blood into the ventricle the valve closing produce sound dub

 blood start flow into the ventricle the cycle is repeated.