Breathing

[BPHgravity]

What is the process/function that allows one to breathe? I imagine it must be some sort of muscular contraction, but that doesn't seem to explain how air can be taken in. Where does the exhaling and inhaling action get its power?

[amoda]

THIS IS A GUESS!!!!!!!1

 

Dosent it have to do with that when the lungs compress it pushes the air out, and when it expands the air outside moves in since it wants to go into a less dense area which would be your lungs at that moment?

[hierarch]

I think amoda is right. The exhaling and inhaling action get its power from the difference of pressure between inside and outside of lung. The air inside has a higer proportion of CO2, and the air outside has a higher proportion of O2, which will result in mass transfer (CO2 move to outside and O2 move to inside). Then the body gets its necessary O2 and releases its useless CO2.

[Glider]

What is the process/function that allows one to breathe? I imagine it must be some sort of muscular contraction, but that doesn't seem to explain how air can be taken in. Where does the exhaling and inhaling action get its power?

 

Breathing is an autonomic function in that it is non-conscious and non-volitional. There is a small nucleus of 'leaky' cells in the brain stem (medulla) that are permiable to sodium. These cells allow sodium to leak in passively until threshold is reached at which point they fire. Being 'leaky' this results in a constant volley of action potentials from that nucleus. This signal results in the muscle groups associated with breathing to contract (e.g. intercostals among others). As these muscles contract, they cause the diaphragm to lower and the rib cage to expand, which increases the volume of the thoracic cavity. This increase in volume results in a drop in pressure and air is sucked into the lungs to compensate.

 

After a certain period, inhibitory interneurons cut in and block the signal from the brainstem and the muscles relax, allowing the ribs and diaphragm to return to their original positions, reducing the volume of the thoracic cavity and forcing air out of the lungs.

 

Due to the neurons responsible for respiration being permiable to sodium, the signal for inhalation is constant, so in effect, we are constantly signalling to breathe in. It is only the timed action of the inhibitory neurons interupting the constant signal that allows the muscles to relax and causes us to breathe out.

 

Respitory rate is controlled by chemoreceptors in the carotid arteries. An increase in levels of CO2 causes blood pH to drop. When the chemoreceptors detect this (e.g. during exercise), they signal other nuclei in the brainstem which increases respitory rate and also recruits other muscles (e.g. deltoids and other groups around the shoulders) which when contracted, increase the overall thoracic volume, so breathing both speeds up and gets deeper.

[amoda]

man, can't belive that something as common as breathing is soo complicated.

[Glider]

It's an important activity

[YT2095]

LOL @ Glider

 

from what I rem from my singing lessons, there 2 sorts of breathing also, those that use intercostal muscles and those that use the Diaphramatic, basicly one is shallow the other deep and from your gut or whatever it`s called as the area below your rib cage.

you can also force it through certain excersizes, if you take your arms out to shoulder height abd bend your elbows so the your hand touch your pectorals, with your mouth open and relaxed throat, if you twist your top half side to side reasonably fast, you`ll actualy hear your lungs breathe without you actualy doing it, it`s the compression/expansion that does it, just like a pair of bellows

 

prolly useless info, but interesting to try

[Glider]

Yep, that's right. One form of breathing is dependent on the intercostals lifting the rib cage. The other is dependent upon the abdominals lowering the diaphragm.

[Radical Edward]

Interestingly, birds have a different breathing mechanism to our bellows type lungs. They have a series of little bags which results in a constant movement of fresh air over the surface of the lungs, unlike our lungs which fill up with waste before we expel it and breathe in some more fresh air again.

[Glider]

Yep, and to make it even more efficient, birds have a counter flow system where deoxygenated blood and fresh air run in opposite directions, ensuring the blood is absolutely saturated with oxygen by the time it leaves the lungs. Very efficient system.