How the Body Works : Each Heartbeat

[radovichhillary]

like your clip .. keep it up =) thanks

[deezTX]

Taking A and P and all the books I have read states it's the valves closing.

[Chlo1234321]

the man speaking sounds like a ped . :S

[hondafaith]

the dub sound is the sound of the valves closing

[nadreas1]

Incorrect. That is a common misconception of the heart sound. The sound that you are hearing is the flow of blod slaming agains the wall of the heart. Consider how small the valves are, how could something that small make a sound that loud?

[Medifro]

do u have a reference?

To my thinking, the sound cannot be anything but a valve closure. Fluid (here,blood) hitting the walls does not make a sound that is singular, but continuous( try firing high pressured water into a glass ). Not to mention the nature of the sound doesn't imply that its made from fluid, but a solid object.

Eagerly waiting for ur response :)

[drugdr2010]

it is definitely valve closure... the "lub" is closure of the AV valves, preventing backflow of blood into the atria, and the "dub" is closure of the semilunar valves

[Medifro]

I checked my sources and refernces again, and thought about the suggestion our beloved collegue made. Wheneever I think about it ( since frankly its an intresting observation ), it makes no sense, and he's saying its a misconception.

This of course not to mention the various signs that follow the sounds, in ECG, Echo, and pressure-volume graphs.

[krsnax1]

@Medifro Sound 2 occurs at the start of diastole (phase 4) when the semilunar valves close. The sounds are not caused by the valve cusps coming together as they shut. They are caused by the turbulent rushing of blood through the valves as they are narrowing and about to close. If you think about the amount of blood that is expelled through the body it makes a lot of sense. I hope this helps. :)

[krsnax1]

@drugdr2010 I'm sorry but its not valve closure. Think of a constant force of water pushing towards the shore. The harder the liquid hits the shore the louder the sound. The liquid is rushing through the cardiovascular system constantly. To shut those valves while the blood continues to try to rush through them causes the liquid to slam against them. If the valves were to close slowly, then you probably would not hear such a sound.

[krsnax1]

@drugdr2010 the valves slamm shut so the blood slamms up against them. So valve closer is part of the process and definately makes it possible but the actual sound is the liquid hitting against them.

[krsnax1]

@Medifro: reference Principles of human physiology 3rd edit.,C. Stanfield & W. Germann copyright 2009 Pearson Edu.Inc. See ch.13, p.383 "Heart Sounds."

Heart sounds heard through a stethoscope 1. Lubb (low-pitched) 2. Dupp (louder, sharper). Lubb (when you compare it to the timing of the events of the cardiac cycle) occurs at the start of systole, when the AV valves close.

[Spetsop]

Actually the normal heart beat sounds (lub-dub; or the S1 and S2) are produced when the blood hits the valves and forces them to close (thus preventing blood flow back). The abnormal heart sounds (the S3 and S4) are made when blood hits either the walls of the ventricles (S4, in a non-compliant heart) or when blood enters the volume overloaded ventricles (S3).

[krsnax1]

@nadreas1 you are absolutely correct. Medfro asked for a reference and I have provided it for him/her.

[mayitpleasethecourt]

this is the how; what about the why?

[razakiani]

wats happened to ur voice,,,,hoarseness

ur suffering frm left atrial enlargement which compresses ur larynx,,,,,,,,,,,

[0gummibaerchen0]

wow that's what i was looking for for the last 2 hours. very good explanation! thanks!

[canada0606]

Question. Why do the pulmonary valve and the aorta valve have to close when the blood is filling in. And why do the other two valves close when blood is pumped out?

[ForsakenEntity93]

so that the pure and impure blood wont mix....

[6feetdownedge]

false

[Emeliee17]

The valves close to stop blood from the ventricles flowing back into the atria. The tricuspid and atrioventricular valve have to close to stop the blood going straight into the ventricles.

[ForsakenEntity93]

which is basically da same thing....

[DEdesigns57]

So wait is there actually a peroid in time when your heart is completly empty of blood, before it recives more?

[Emeliee17]

Your heart's never empty, there's always some blood left in

[6feetdownedge]

your body always has at least 1 third of your ventricles filled with blood all the time. if your heart is bigger than that, your heart is diseased

[liendesmet]

lub-dub-pause lub-dub-pause

It's like a waltz

Damn, studying can be so much fun! ;-)

[Saira93]

AGREED 8D

[syaosher]

Thank you!

[100isthebest]

i had taken this lesson in biology few hours ago that is interesting and very diffucult iam confused can anyone explai this !?

[underageplayer]

ppl r confused themselves

[underageplayer]

ppl r confused themselves

[bonoervers]

interesting and useful. Thanks!

[tonyballa07]

this must be the founatin of youth