[XM8]

Hi,

I've got a test coming up in a week on the cardiovascular and circulatory system and I'd like some help because I'm stuck :confused:

Now my teacher (whom I cannot understand) was talking on and on about two parts of the heart, the left and the right, one of them (I think the right part) contains blood which contains mostly CO2 while the other contains mostly O2. One side pumps blood to the brain while the other pumps blood to the lungs etc. etc.

Anyway if someone could please explain the whole system and process simply I would really appreciate it.


Thanks,

-Xm8

[sarnian]

Hello XM8

One side of the heart (right atrium) receives blood returning from the body tissues. The output of the heart (right ventricle) pumps this blood under pressure into the lungs where the CO2 is exchanged with oxygen.
From the lungs the blood returns into the other side of the heart (left atrium), that pumps the blood under pressure (left ventricle) into the aorta, from where it goes to the tissues again (including the brain). It is (of course) a 'closed loop' system !

Two atriums/ventricles allow a better oxygenation of the blood in the lungs, and sufficient pressure of the blood to reach all body tissues.

Have a look at this drawing that shows how the blood circulates through the body (LINK)

Success with the test!

[XM8]

Sarnian, thanks for your answer.

We disected a sheep's heart the other day in class and we saw everything in detail but I don't think I understood everything

Anyway just to sum up what we wrote down. Blood, filled with O2 goes to the left atrium by passing through 4 veins. It is then let down into the left ventricule when the valve muscles or (Chordae tendinaea) are relaxed. When they are contracted, this prevents the blood from going back up.

The blood thereafter somehow? Gets into the right atrium. Those valve muscles decontract, letting the blood go up into the right ventricule and then they circulate into the lungs as blood mainly containing CO2. It is then remixed with fresh O2 which the person breathes in and the process restarts.

Am I correct in my explination or is there something important that I'm not getting here?

I guess detail counts a lot in this test (I'm in grade 10).

Thanks a lot for your help,

-Xm8

[sarnian]

XM8

You have the valve action OK, but you are following the wrong sequence with the blood circulation.
See the drawing I provided! (Follow the link). Blue is blood with CO2 and red is with O2.

From the body tissues blood with CO2 is pumped into the heart (right atrium), and leaves the right ventricle under high pressure to the lungs, where CO2 is replaced with O2.
From the lungs the blood returns into the heart (left atrium) and leaves the left ventricle under high pressure into the aorta, towards the body tissues again.

So blood flows from the body tissues into the right atrium and ventricle, than towards the lungs where CO2 is replaced with O2, than to the left atrium and ventricle, and than back again to the body tissues.

Success with the test!