 Hi everybody, Dr. O. This video will be partially a review because we would have covered these structures when we talked about the brain and more importantly the brainstem, but I want to talk about the neurological control of breathing mainly because of how it ties into our discussions in the future about acid-base balance. So as you can see here, there are two different parts of the brainstem that play a big role in breathing. You have the medulla oblongata is going to house the dorsal respiratory group and the ventral respiratory group. The dorsal respiratory group is responsible for quiet breathing. So it constantly tells the diaphragm and the external intercostals breathe in, breathe out. The ventral respiratory group is activated during forced breathing. So it's going to bring in the accessory muscles of respiration, your scalenes, your internal intercostal muscles, these types of muscles here and then your abdominal muscles with forced exhalation. So remember the dorsal respiratory group responsible for quiet breathing, ventral respiratory group responsible for forced breathing, but then we have the pons or what's known as the pontine respiratory group. This is going to be what controls the rate of respiration. So hopefully you remember when you learned about the nervous system that the respiratory rhythmicity centers breathe in, breathe out, they're in the medulla oblongata. The respiratory rate centers are in the pons and the reason this is so important is because the pons is constantly monitoring the chemical composition of your body fluids and it's going to control respiration based on that. But you might think it's primarily worried about oxygen, but it isn't. Carbon dioxide, this metabolic waste product, your nervous system is much more sensitive to changes in carbon dioxide than it is to oxygen. That's because we have a lot of extra oxygen. We obviously need a constant flow of oxygen, but we can survive at higher altitudes, etc. But carbon dioxide becomes a weak acid called carbonic acid. So carbon dioxide changes are going to lead to pH changes pretty quickly. So this is when the pons is going to step in and say, okay, we've got, so let's say we're building up too much carbon dioxide. The pons is going to notice that our pH is starting to drop. We could die because of this condition. So the response will be to breathe faster, to blow out more carbon dioxide. On the flip side, if carbon dioxide levels were getting low, which is primarily caused by hyperventilation, right, if somebody's hyperventilating, they're blowing out too much carbon dioxide, we have to slow their breathing so that they leave that carbon dioxide in their bloodstream. This is why if someone is hyperventilating, you have to breathe into a bag. You want them to breathe that used air back in to get that CO2 back into their system. But that's pretty rare compared to pH problems with too much carbon dioxide, and we'll cover all that in a later chapter. But the two parts here of the PON team respiratory group, you have the pneumotaxic center and the apnoostic center. So the pneumotaxic center is basically going to control, it's going to determine the rate of breathing. So it's going to be the part that says when you should inhale, when you should exhale. So the pneumotaxic center will change your respiratory rate based on what's happening. Again, too much CO2 in your system, the respiratory rate will go up to blow it out, too little CO2 in the system, your respiratory rate will drop to capture it and keep it in. The apnoostic center will determine the depth of breathing. So you can breathe deeper or more shallow breaths based on how much CO2 you should be getting rid of. All right, so that is the neurological control of breathing. Hope this helps. Have a wonderful day. Be blessed.