In this lesson, we'll learn how you are able to breathe without even thinking about it. You'll also find out why you breathe faster when you run. Finally, we'll learn where things as diverse as sneezing and blood pressure are controlled.
Did You Remember to Breathe?
I'm sure you know that your heart is a pretty large structure: about the size of your fist. Your lungs are obviously even bigger in size. But did you know that the speed at which your heart beats and your lungs breathe are in large part controlled by areas of your brain sometimes as small as a thumbtack?
Amazing, isn't it? A tiny little area in your brain is what gives you the ability to breathe and enjoy life. These little areas are located in two important areas of your brain stem, known as the pons and medulla oblongata. We'll also learn about their structure and function, including chemoreceptors, pH sensing, and breathing rate.
Not only do these areas control your heart and lungs, but they also monitor your blood pressure and the acidity of your blood in order to adjust your breathing rate automatically. Your brain essentially has autopilot zones, which allow you to focus on things, like studying for an exam, watching television, or texting a friend, without having to worry about remembering to breathe.
The pons regulates respiratory functions.
With that in mind, a major structure in the upper part of your brain stem is called the pons. The pons has two over-arching roles. The first is the regulation of breathing. In the pons, there is a structure called the pneumotaxic center. This is really just a big word for a center of nerve cells that control the amount of air you breathe and how many times a minute you take a breath, which is known as the breathing rate. For example, when you run, you begin to breathe faster, and when you lie down on the couch to rest, you breathe more slowly. This breathing rate is regulated in part thanks to the pons.
In addition, the pons is involved in the transmission of signals to and from other structures in the brain, such as the cerebrum or the cerebellum. The pons is also involved in sensations such as hearing, taste, and balance. Finally, the pons is also involved in the regulation of deep sleep.
The Medulla Oblongata's General Functions
Whereas the pons is located in the upper part of the brainstem, the medulla oblongata is a structure located in the lower half of the brainstem. Just because the medulla oblongata is beneath the pons doesn't mean it's any less significant. In fact, they often work in tandem on issues such as breathing.
The medulla oblongata is located in the lower portion of the brainstem.
In addition, the medulla oblongata is very important in things like your heart rate and blood pressure. Furthermore, it's responsible for many reflexes in your body, or things you usually do not voluntarily control, such as vomiting, sneezing, and coughing.
The Medulla Oblongata's Specific Role in Breathing
Finally, the medulla oblongata has a really cool thing it can do. Let's use an example to illustrate what this function is.
Pretend that you are running a race. You know that you need lots of oxygen in order to run the race. However, as you begin to run, your body also begins to build up a lot of carbon dioxide as a result of all of that running. The carbon dioxide is no good when it comes to helping you run the race. This is because as the CO2 in your body increases, the acidity of your blood increases as well. The increased acidity means a lowered pH of your blood. If you don't remember what low or high pH levels are, recall that low levels of pH imply increased acidity and high levels of pH imply increased alkalinity of a substance.
With that in mind, the medulla oblongata has very special nerve cells that can sense the pH level of your blood. These specialized nerve cells, which sense chemical changes in the environment, are called chemoreceptors. You can remember this because the root 'chemo-' in chemoreceptors refers to the chemicals these receptors sense.
The chemoreceptors detect pH levels in the body.
The ability of chemoreceptors to detect changes in pH is known as pH sensing. Once the chemoreceptors sense your blood's lowered pH, the medulla oblongata triggers you to breathe faster in order to get rid of the harmful excess carbon dioxide and therefore increase the pH of your blood back to normal.
As you can tell by now, both the pons and the medulla oblongata are critical for breathing, among many other functions.
I know there was a lot of information in this lesson; therefore, we should review it one more time.
Remember: the medulla oblongata is a major structure located in the lower half of the brainstem. It is responsible for the regulation of your heart rate, breathing, and blood pressure as well as reflexes such as vomiting, sneezing, and coughing.
The medulla oblongata has specialized nerve cells, which sense chemical changes in the environment, called chemoreceptors. These chemoreceptors are involved in a process that detects the level of acidity or alkalinity, the pH, of your blood in a process we call pH sensing.
The medulla oblongata, through these chemoreceptors, can alter your breathing rate if necessary in order to get rid of excess carbon dioxide that causes the pH of your blood to decrease.
Besides the medulla oblongata, your brainstem also has a structure called the pons. The pons is a major structure in the upper part of your brainstem. It is involved in the control of breathing, communication between different parts of the brain, and sensations such as hearing, taste, and balance.
After finishing this lesson, you should be ready to:
- Describe the functions of the pons and the medulla oblongata
- Explain how the medulla oblongata regulates breathing
- Define chemoreceptors and pH sensing