[XM8]

Hi,

I've got a biology test next Monday and need to ace this test.

I had one about the heart last Thursday which if I may say so I did an excellent job on.

There are just a few things I need to clarify so that I'm confident I know the chapter.

Today we studied the PO2, which if I recall correctly means Pressure of Oxygen. Now there are certain things one has to remember, such as the pressure of blood going from the lungs to the heart, which I think is 106 PO2, however it is 104 when going back into the lungs from the pulmonary artery, etc.

It wouldn't be a problem for me to learn these numbers it's just that I don't fully understand the concept of this pressure stuff.

What does it really mean, what is the point of it?

Btw, is it true that people who do bungy jumping sometimes die because they fall so fast that there is a rapid pressure change and their lungs exhale O2 instead of CO2?

Another thing is that for athletes to be able to increase their VO2 max, they must increase the amount of blood rich in O2, pumped out of the heart during systole. However by doing this they decrease their heart rate. Is this correct? If so could someone please go into a bit more detail?


Any help will be most appreciated,

Thanks a lot,

-Xm8

[sarnian]

Hello XM8

On the pressure issue :

'The pressure of blood going from the lungs to the heart, which I think is 106 PO2, however it is 104 when going back into the lungs from the pulmonary artery, etc.'

As can be seen from this graphic (link1) and also of this graphic (link2)

The low pressure oxygen poor blood returns from the body tissues through the veins into the heart (right atrium), leaves the right ventrical under pressure and flows into the lungs where CO2 is replaced with O2. This process reduces the pressure of the blood. Than the blood returns to the heart (left atrium) and leaves the left ventrical under pressure into the aorta towards the body tissues.

So blood pressure into the atrium is always lower than that coming out of the ventrical.
And blood pressure into the lungs (and into body tissues) is always higher than that returning from the lungs (and body tissues) into the heart.

As to breathing by athletes : their heart rate may go slow when in rest, but their lung capacity is increased.
During heavy load a fast heart beat combined with high lung capacity allows a bigger oxygen supply to the body tissues.

And as to bungy jumping : may be it is more a case of cardiac arrest from pure fright? :)

[XM8]

Thanks for that great answer. Very helpful indeed.

If I have anymore questions I'll post back here, because I'm at school right now and I don't have my biology stuff.

Thanks again,

-Xm8

[XM8]

Ok well I've been looking through my biology lesson and I've come across 2 things I'm not so sure of.

Maximum Aerobic Speed (MAS) and Maximum Aerobic Capacity (MAC). I know they have something do with the VO2 Max (I know what that is).

Can anyone explain please?

Thanks,

-Xm8

[sarnian]

Hello XM8

Next time please post new questions in a new topic!

VO2max is the maximum amount of oxygen in millilitres in the blood.

Maximum Aerobic Speed (MAS) is about the relationship between oxygen supply and the time the activity can be maintained.

Maximum Aerobic Capacity (MAC) is the relationship between an activity and the max. oxygen consumption needed for that activity.

VO2max is important in both cases, as if there is more oxygen in the blood, the activity can be maintained longer (MAS), and the activity can be done faster and/or easier (MAC).

[XM8]

Hey Sarnian,

Sorry about that will do :).

Thanks a lot for the great answer :D

KIR,

-Xm8

[sarnian]

Hello Kir,

Just keep that lovely human heart pumping ! :)