Biology.

[SomeStudent]

I want some help here. Can someone tell me the pressures in the ventricles/atrium of the heart during a cycle? and the valves: when do they open/close and which ones are they?

 

[U stalking ME]

r u a levels or o levels student? i am askin coz a lot depends on that, u need to noe ecg graph if u r a-levels student

Atrial Systole

The contraction of the atrium causes a rise in pressure in the atria. This pressure rise is called the a atrial pressure wave; it pushes any blood left in the atria into the ventricles.

Ventricular Systole

As the ventricles contract the ventricular pressure begins to rise. As soon as the ventricular pressure surpasses the atrial pressure the A-V valves close. The rapid closing of the valves causes a rise in pressure in the atria which is known as the atrial pressure wave. What follows is a short period of time called isovolumic (or isometric) contraction, during which all four valves of the heart are closed. During this short phase (approximately .025 seconds) the volume in the ventricle remains unchanged (hence the term isovolumic) but the the tension in the muscle and the pressure in the ventricle is increasing rapidly. The pressure quickly rises to a point above that of aortic and pulmonary pressures; when this occurs the aortic and pulmonary valves are forced open and blood flows into the aorta and pulmonary artery. Both pressures begin to fall to a point when the ventricular pressures are lower than the aortic and pulmonary pressures. At this point the pressure difference causes the aortic and pulmonary valves to close. The rapid closing of the valves causes a pressure rise in the aorta and isovolumic (or isometric) relaxation, during which all four valves of the heart are closed. During this phase, again, the volume of the ventricles remains unchanged even though the muscle relaxes and the pressure in the ventricle rapidly drops.

Diastole

At the point when the ventricular pressure drops below that of atrial pressure the A-V valves open. The blood pressure which has slowly built up in the atrium during ventricular contraction causes blood to quickly flow into the ventricle (this is known as rapid inflow). The pressure build up and release in the atrium during ventricular contraction can be seen as a wave and is called the atrial pressure wave.

 

[SomeStudent]

r u a levels or o levels student? i am askin coz a lot depends on that, u need to noe ecg graph if u r a-levels student

Atrial Systole

The contraction of the atrium causes a rise in pressure in the atria. This pressure rise is called the a atrial pressure wave; it pushes any blood left in the atria into the ventricles.

Ventricular Systole

As the ventricles contract the ventricular pressure begins to rise. As soon as the ventricular pressure surpasses the atrial pressure the A-V valves close. The rapid closing of the valves causes a rise in pressure in the atria which is known as the atrial pressure wave. What follows is a short period of time called isovolumic (or isometric) contraction, during which all four valves of the heart are closed. During this short phase (approximately .025 seconds) the volume in the ventricle remains unchanged (hence the term isovolumic) but the the tension in the muscle and the pressure in the ventricle is increasing rapidly. The pressure quickly rises to a point above that of aortic and pulmonary pressures; when this occurs the aortic and pulmonary valves are forced open and blood flows into the aorta and pulmonary artery. Both pressures begin to fall to a point when the ventricular pressures are lower than the aortic and pulmonary pressures. At this point the pressure difference causes the aortic and pulmonary valves to close. The rapid closing of the valves causes a pressure rise in the aorta and isovolumic (or isometric) relaxation, during which all four valves of the heart are closed. During this phase, again, the volume of the ventricles remains unchanged even though the muscle relaxes and the pressure in the ventricle rapidly drops.

Diastole

At the point when the ventricular pressure drops below that of atrial pressure the A-V valves open. The blood pressure which has slowly built up in the atrium during ventricular contraction causes blood to quickly flow into the ventricle (this is known as rapid inflow). The pressure build up and release in the atrium during ventricular contraction can be seen as a wave and is called the atrial pressure wave.

GAAAAAH THANK YOU SO MUCH! I am an O levels student and that helped A LOT. like really. You rock! Thanks again!

 

[U stalking ME]

GAAAAAH THANK YOU SO MUCH! I am an O levels student and that helped A LOT. like really. You rock! Thanks again!

oh okay, u r welcome