Control of breathing is quite complex
And if you really check the specs
You find all kinds of balances and checks
Within the medulla, cells playing their role
The DRG, inspirational control
Using cyclic neurons for their goal.
Actions potentials from the DRG
These cells are cyclic and fire intermittently.
Then muscle contract to the best of their ability.
To the external intercostals and diaphragm they talk
And these muscles, at the neurons’ stalk
Follow orders and they do not balk.
And when they stop, the muscles relax.
Air is forced out as muscle slacks.
Volume decreases and Boyle’s Law acts.
So breathing in costs ATP
That means the use of energy
But calm expiration? It’s just free.
But when you need to force air out
Or at something, really shout
The VRG is what it’s all about.
It talks to abdominal muscles as well
As internal intercostals to make pressure swell
And air in the lungs can no longer dwell.
The Apneustic center in the pons is a source
Of a center dealing with force
Of an inspiration’s course.
The pneumotaxic center deals with duration
And both centers talk to each medullary station
And help regulate breathing condition.
The limbic system has some sway
In breathing fast or slow at bay
More than most realize, an important say.
And the hypothalamus, always of import
With its influence never falls short
In aiding ventilation, it lends its support.
For other than limbic, it deals with fever
When it tips the temperature lever
And makes ventilation a greater achiever.
Lastly there’s the cortex of the brain,
Whose job most think, is always to reign.
But when it comes to breathing, it is quite plain.
You can’t stop breathing by your will.
The lower centers always still
Make breathing a reflex, cortex input almost nil.
And just what drives this reflex to ventilate?
From where does the need originate?
From the chemoreceptors, it does emanate.
Receptors monitoring proton concentration.
Then messages sent without cessation
To the brainstem for increasing ventilation.
And hydrogen ions, where are they from?
Carbon dioxide and water, voila, they come.
The magic formula, carbonic acid does succumb.
Copyright © LR Waldman | Year Posted 2016
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