Just started studying the anatomy of the heart and I have a question????

[alysp13751]

Ok, so without getting into physiology because thats a second year subject and im in first year, can somebody explain to me systole and diastole???

What I got from reading the book is that the filling phase is ventricular diastole, so this means the atrioventricular valves have to be opened. This is what I do not understand. Do the papillary muscles contract and pull the cusps downward exerting a force on the chorda tendinae? it doesnt make sense to me, because when they relax, the cusps should prolapse into the atrium and it says in the book that never happens? and same on ventricular systole, how do the cusps close without prolapsing into the atrium? either the chorda tendinae are the same length through the whole process and they do not act like normal tendons and the papillary muscles are the ones that get further and nearer or I do not understand.

Can someone explain this to me in a basic way without getting into complicated physiology??? thanks

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[dragon529]

The papillary muscles/chorda tendinae do not actively contract. The whole process is governed by the different pressures in different chambers of the heart during different times. For ex., when atrial pressure is greater than ventricular pressure, AV (tricuspid and mitral) will open. But when ventricular pressure is greater than atrial P, AV valve will close. At this time, Aortic and Pulmonary valves will remain close UNTIL the ventricular P is greater than the systemic/pulmonic P than the valves will be bust open. Just remember the chorda tendinae is there to PREVENT prolase. They are there just for a protective service. Different pressures during different times will govern the cardiac cycle.

 

[JackShephard MD]

Ok, so without getting into physiology because thats a second year subject and im in first year, can somebody explain to me systole and diastole???

What I got from reading the book is that the filling phase is ventricular diastole, so this means the atrioventricular valves have to be opened. This is what I do not understand. Do the papillary muscles contract and pull the cusps downward exerting a force on the chorda tendinae? it doesnt make sense to me, because when they relax, the cusps should prolapse into the atrium and it says in the book that never happens? and same on ventricular systole, how do the cusps close without prolapsing into the atrium? either the chorda tendinae are the same length through the whole process and they do not act like normal tendons and the papillary muscles are the ones that get further and nearer or I do not understand.

Can someone explain this to me in a basic way without getting into complicated physiology??? thanks

This is physiology at this point. AV valves are open during diastole, then the papillary muscles contract because a huge amount of pressure is about to be created in the ventricles and they want to prevent both regurgitation into the atria and prolapse of the AV valves. This isn't an overly complicated question, you should probably find a book or wikipedia article.

 

[JackShephard MD]

The papillary muscles/chorda tendinae do not actively contract. The whole process is governed by the different pressures in different chambers of the heart during different times. For ex., when atrial pressure is greater than ventricular pressure, AV (tricuspid and mitral) will open. But when ventricular pressure is greater than atrial P, AV valve will close. At this time, Aortic and Pulmonary valves will remain close UNTIL the ventricular P is greater than the systemic/pulmonic P than the valves will be bust open. Just remember the chorda tendinae is there to PREVENT prolase. They are there just for a protective service. Different pressures during different times will govern the cardiac cycle.

Chordae tendinae do not contract, but the papillary MUSCLES definitely contract. In fact, the rarely seen U wave in an ECG is sometimes papillary muscle repolarization.

Wikipedia is your friend in medical school.

 

[alysp13751]

Chordae tendinae do not contract, but the papillary MUSCLES definitely contract. In fact, the rarely seen U wave in an ECG is sometimes papillary muscle repolarization.

Wikipedia is your friend in medical school.

how do the papillary muscles contract? do they have an action on the valves or is it how he said and valves only open and close by pressure? when you say they contract by the pressure how can that be, I thought the only way a muscle could contract was with innervation

btw I can read all I want, but it doesnt exactly answer my question like when you ask someone, we havent started with the heart, we start next week, so Im reading ahead and cant ask my teacher just yet, so more input pretty please?

 

[JackShephard MD]

how do the papillary muscles contract? do they have an action on the valves or is it how he said and valves only open and close by pressure? when you say they contract by the pressure how can that be, I thought the only way a muscle could contract was with innervation

btw I can read all I want, but it doesnt exactly answer my question like when you ask someone, we havent started with the heart, we start next week, so Im reading ahead and cant ask my teacher just yet, so more input pretty please?

They contract in response to an impulse beginning at the SA node not because of pressure, my statement was WHY they contract. You're making this too complicated. The muscle contracts, it is tethered to the valves by cords, and they keep the valves from prolapsing into the atria. Their action is creating tension. I suggest you wait until you cover it and have a dialogue with your teacher. Honestly, I rarely ask professors anything. Almost everything you need to know can be found online or in a text/review book.

 

[alysp13751]

They contract in response to an impulse beginning at the SA node not because of pressure, my statement was WHY they contract. You're making this too complicated. The muscle contracts, it is tethered to the valves by cords, and they keep the valves from prolapsing into the atria. Their action is creating tension. I suggest you wait until you cover it and have a dialogue with your teacher. Honestly, I rarely ask professors anything. Almost everything you need to know can be found online or in a text/review book.

ok thanks

 

[D elegans]

This was actually a question that was brought up by several people in my class when we were dissecting the heart. I think the concept of its main utility being to prevent prolapse is not intuitive.

 

[TallScrubs]

In the beginning of systole, as the ventricles contract, the force of the blood (which is being pressurized) pushes the valve closed to prevent blood from flowing back into the atria. This is a passive process.

However, the force of that blood would push the valves open (into the atria) if there was no papillary muscles/chordae tendinae to keep them closed.