Source: Video and Images Created by Amanda Soderlind
Welcome to this lesson on controls over breathing. Today we are going to be discussing how the nervous system controls aspects of our breathing.
So, the nervous system does play a role in certain aspects of our breathing. And some of these aspects include muscle movement and frequency of breathing. So, the types of muscle movement that your nervous system can control are the intercostal rib muscles, which are those muscles in between each of your ribs. And also your diaphragm. So, the nervous system plays a role in controlling these muscles, which both play an important role in the process of breathing by regulating pressure in the chest cavity.
The nervous system also can control your frequency of breathing. And your frequency of breathing is actually controlled by carbon dioxide levels. So, your brain is able to detect carbon dioxide levels in the blood and then, depending on what those levels are, your frequency of breathing is determined. If those levels are high, you will breathe more frequently. If they're low, you need to breathe less frequently.
So chemoreceptors, which are a type of sensory receptor, detect gas levels. All right? So these chemoreceptors are actually found in your brain and in arteries. So some of these chemoreceptors that are found in your arteries are carotid and aortic bodies. So, these carotid and aortic bodies contain these chemoreceptors, and so they're able to detect shifts in carbon dioxide and oxygen levels. So as blood passes through these carotid and aortic bodies, they can kind of take an inventory on how much carbon dioxide and how much oxygen is being carried by the blood and then determine if respiration has to change to make up for that or not in order to maintain homeostasis.
So, respiration is controlled by your brain stem, which is composed of the medulla the pons. So, neurons in your medulla are like pacemakers for breathing. So, they're able to also detect and regulate the carbon dioxide and oxygen levels in your blood. And if those levels are too high or too low, they will alert your body to either breathe more heavily or to do something in order to maintain homeostasis.
So, the activity level also can change our breathing patterns. So as you exercise, your muscles are working harder, your cells are producing more CO2, and they need more oxygen to sustain that activity. So as you exercise, you'll have to breathe more heavily and more frequently to take in the oxygen that you need, and get rid of the CO2 that is being built up. So, activity level is something that can change your breathing pattern.
So, that's something that you could have control over. If you were really working out, you can force yourself to breathe more heavily to get in more oxygen. But generally most aspects of our breathing are not under conscious control. We don't really think about it consciously when we're breathing. Our body just kind of does it for us.
So, what we're going to do right now is just kind of take a look at an example of how the nervous system controls our breathing. So, first thing that has to happen is stimulus has to be detected. So we're going to say that that stimulus is that the chemoreceptors in your body detect a rise in CO2 concentration levels. OK? So, the stimulus is the rise in CO2. Chemoreceptors would then detect that stimulus. So, you have a rise in CO2 levels. Chemoreceptors, such as a carotid or aortic bodies or the medulla, are going to detect that rise in CO2. And so to make up for that rise in CO2, your breathing rate and your tidal volume will change.
OK? So, because you have this extra CO2 in your blood, we need to try and make up for that to maintain homeostasis. We need to breathe more frequently and more heavily to get in more oxygen, in order to help maintain this homeostasis-- to reverse the stimulus. OK?
So then, if we were to breathe heavily and deeply for long enough we would be able to reverse that stimulus. We'd be able to reverse that stimulus to maintain homeostasis.
So, this is an example of a negative feedback loop that could be found in your body related to the respiratory system. And remember, negative feedback loops help maintain homeostasis by detecting a change and then reversing that change. So we're detecting the stimulus, our body is doing something in order to reverse that stimulus to maintain homeostasis.
So, this lesson has been an overview on controls over breathing and how the nervous system controls aspects of your breathing.
A class of receptors that detect chemical changes within the body (example: pH changes).
Chemoreceptors found within the carotid bodies that are sensitive to changes in blood pH; carotid bodies are in constant communication with the brainstem via the glossopharyngeal nerve.
Chemoreceptors found within the aortic arch that are sensitive to changes in blood pH; aortic bodies are in constant communication with the brainstem via the vagus nerve.