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Explain events that take place in one heartbeat

I know this is talking about the cardiac cycle
But I am not sure about what the events are exactly

I have brief summary/steps but I think I did it wrong :frown:
I don't understand the events in the cardiac cycle
Where about does atrial systole, ventricular systole, diastole all come

I honestly dont know how to answer this question:colone:xplain events that take place in one heartbeat

This is my attempt, please feel free to correct, add anything:
Blood drains into left atrium from lungs along pulmonary vein
Raising ig blood pressure in left atrium forces left atrioventricular valve open
Contraction of left atrial muscle forces more blood through valve
As soon as left atrial systole (muscle contraction) is over, left ventricular muscles start to contract. This is called ventricular systole
This forces left atrioventricular valve to close and opens valve in aorta. Blood then leaves left ventricle along aorta
(edited 2 years ago)
Original post by Medic Mind
Hey there!
Honestly great job with your explanation! It's definitely a good start to understanding the cardiac cycle as a whole.
Just to expand a bit, the cardiac cycle consists of 4 general steps
Step 1: Atrial Diastole- If we are considering the left atrium, then the blood would enter the atrium via the pulmonary vein (the pulmonary valve is OPEN and the atrioventricular valve is CLOSED). As the volume of blood in the chamber increases, so does the pressure. This causes the pulmonary valve to CLOSE, increasing the pressure of the chamber. The atrioventricular valve then OPENS and blood flows to the ventricle.
Step 2: Ventricular Diastole- As the blood is passively flowing from the atrium to the ventricle, the muscles of the ventricle are relaxed for just a bit, allowing the blood to fill the chamber. The atrioventricular valve is OPEN and the mitral valve is CLOSED.
Step 3: Atrial Systole- At this point the majority of the blood has travelled to the left ventricle; however, in an effort to get the last bit of blood out of the atrium, the muscles of this chamber contract. Once this occurs, the antrioventricular valve is then CLOSED as a result of the pressure that is beginning to build in the ventricle. The mitral valve is also CLOSED, which means that the ventricular pressure continues to build.
Step 4: Ventricular Systole- This vast increase in pressure causes the mitral valve to OPEN. At a similar time, the ventricle contracts, pushing the blood from the left ventricle through the aorta to the rest of the body.

Hope this helps!
Dottie
Medic Mind

With due respect to your position as "Rep", there are some crucial errors here:-

a] Step 2: The mitral valve is ITSELF an atrioventricular valve [between the left atrium and L ventricle], the other A-V valve being the triscuspid valve between the right atrium and R ventricle. Therefore when you say "The atrioventricular valve is OPEN and the mitral valve is CLOSED", this is a self-contradiction.

b] Step 1: The pulmonary valve lies at the opening of the pulmonary ARTERY from the right ventricle - hence, it has nothing to do with the left atrium, into which the pulmonary VEINS drain [bringing blood from the lungs].

c] Stage 3: Once again there is confusion between atrioventricular valve and mitral valve [the A-V valve on the left side of the heart IS THE MITRAL VALVE!!

d] Stage 4: You appear to be confusing the mitral valve with the aortic valve here - if as you say "the mitral valve to open" then blood would be forced back into the left atrium from the L ventricle [this ONLY OCCURS in a patient with mitral regurgitation - HERE WE ARE REFERRING TO A NORMAL HEART!!

Sorry to have to say this, but your username is a misnomer.

M
@Jpw1097 @Reality Check

Good evening doctors,

It is apparent that the so-called user "@Medic Mind" have a grossly deficient knowledge of human anatomy and physiology, at least of the heart, and are hence misleading medical students RATHER THAN "helping them" as they claim - may I request you to confirm that my criticism of their answer above [which, interestingly, they have deleted now!!, but is visible as one I have replied to due to the ingenuity of TSR!], is actually valid criticism.

May I point out that I have nothing to gain by pointing out these errors except the satisfaction of knowing that doctors-in-training are not being taught falsehoods, especially if they happen to be paying for this to incompetent businessmen.

Thank you and be safe!

M
(edited 2 years ago)
Reply 3
Original post by macpatgh-Sheldon
@ecolier @Jpw1097 @Reality Check

Good evening doctors,

It is apparent that the so-called user "@Medic Mind" have a grossly deficient knowledge of human anatomy and physiology, at least of the heart, and are hence misleading medical students RATHER THAN "helping them" as they claim - may I request you to confirm that my criticism of their answer above [which, interestingly, they have deleted now!!, but is visible as one I have replied to due to the ingenuity of TSR!], is actually valid criticism.

May I point out that I have nothing to gain by pointing out these errors except the satisfaction of knowing that doctors-in-training are not being taught falsehoods, especially if they happen to be paying for this to incompetent businessmen.

Thank you and be safe!

M

I agree with all your points, clearly a lot of confusion over the valves.
Atrial systole
Ventricular systole
Diastole

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