Negative vs Positive Pressure: Help

[Sloo0]

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Can someone please explain Negative vs Positive pressures in as much detail as you can muster.

In terms of vasculature, lungs, breathing, etc.


Where in the body has which pressure?

Under what circumstances do the pressures change? (i.e. Valsalva etc)

What does negative pressure accomplish vs positive pressure?


This subject has plagued me more than you can imagine and I cant really find any good explanation.



Danke.

 

[Anastomoses]

Can someone please explain Negative vs Positive pressures in as much detail as you can muster.

In terms of vasculature, lungs, breathing, etc.


Where in the body has which pressure?

Under what circumstances do the pressures change? (i.e. Valsalva etc)

What does negative pressure accomplish vs positive pressure?


This subject has plagued me more than you can imagine and I cant really find any good explanation.



Danke.

Most of the body tissues have negative pressure slightly below atmospheric, more negative in the lungs during inspiration...but...I'm more puzzled as to how a medical student doesn't understand this very basic concept. Where are you in school?

 

[Sloo0]

Thanks for your input, anyone else feel like helping out?

 

[macstjo]

Thanks for your input, anyone else feel like helping out?

You'd have a better chance if you just look it up
Such basic concepts are readily accessible, say Wikipedia?

 

[Sloo0]

You'd have a better chance if you just look it up
Such basic concepts are readily accessible, say Wikipedia?

You're right, I never thought about that, clearly I have come here as a first resort as opposed to a subsequent attempt when other sources have failed.

Thanks for the advice.

 

[Anastomoses]

You're right, I never thought about that, clearly I have come here as a first resort as opposed to a subsequent attempt when other sources have failed.

Thanks for the advice.

I'm not taunting. Guyton - Chapter 15. That should cover almost everything.

 

[lm1120]

The lungs never have a negative pressure, if that was the case they would collapse, however the chest wall does have negative pressure. As you are about to inhale your diaphragm contracts and it creates a negative pressure on the chest wall. At this point the chest wall pressure is more negative than the lungs are positive. The sum of the pressures between the lung and the chest is negative so that draws air in. When you exhale, its a passive process, when you relax your diaphragm, that diminishes the negative pressure and the sum is now positive so air is released. At the end of relaxed exhalation aka FRC, the sum of the pressure is 0 so air is not moving in or out.