Source: Video and Images Created by Amanda Soderlind
In this lesson today, we are going to discuss the three main areas of the brain, their functions, and also some of the brain's protective barriers. So let's start with the three main regions of the brain. So the brain is the control center of our nervous system and it's divided into three main regions. We have our forebrain, midbrain, and hindbrain.
So in green here, I've color coded the forebrain. So the forebrain is the most highly developed part of our brain, and it includes the two hemispheres of the cerebrum, the thalamus, and the hypothalamus. And in future lessons learned other lessons if you want to research more about what these parts of the brain do, you can find those in other lessons.
The hindbrain, in pink here, is located just above the spinal cord and it includes the parts of the brain such as the medulla oblongata, the cerebellum, and the pons. And then our midbrain, which is just this little part labeled in blue here, is the smallest region of our brain. And the function of the midbrain is to relate information from the body's sensory organs to the forebrain, where that information can then be processed. So those are the three main areas of our brain, the forebrain, the hindbrain, and the midbrain.
So we're going to take a look at a diagram that's going to discuss the brain's protective barriers. So the brain is composed of three layers of meninges, and meninges are just membranes of connective tissue, and they're located between the skull and the brain. And the purpose of these three layers is to cover the central nervous system's neurons and blood vessels. So it's protecting the brain, protecting those neurons and blood vessels associated with the brain.
So our first layer we have on the top here, this is not one of the meninges, but this is just our skin. And below our skin, we have bone. And then below that, we have our three layers of meninges that I had mentioned.
The first layer is called the dura matter. So this is kind of a thick, leathery layer that composes the first layer of meninges found right underneath your skull. And then our next layer is the arachnoid matter, followed by the pia matter.
And as we move down this way, the layers of the meninges get thinner and more delicate as we move down. So our first layer is very thick and leathery. Our next layer is a little bit thinner and a little bit more delicate. And then our pia matter is very thin and very delicate. And then right underneath that, is where we would have the brain.
So those are some protective layers of the brain, some protective features of the brain. Some other features of the brain that serve as protective barriers are the cerebral spinal fluid, which acts to cushion the brain. So the cerebral spinal fluid is actually formed from blood plasma.
And then something else that we have is our blood brain barrier. And our blood brain barrier controls what blood-borne substances are allowed to enter the cerebral spinal fluid. So the two of these kind of work together in order to protect the brain.
So that blood brain barrier, the reason that it's so protective and the reason that it can control what substances can enter the cerebral spinal fluid is because the capillary walls of the barrier are much less permeable to substances than other capillaries found in your body. So it helps to control the spread of viruses, toxins, bacteria from having contact with the brain. So we don't want those types of things entering our cerebral spinal fluid because our brain is such an important part of our nervous system, and of our entire body, that we need to make sure that whatever is entering that is controlled. And so that's where our blood brain barrier comes into play, controlling what is going to allow into the cerebral spinal fluid and allowed to have contact with the brain.
However, the blood brain barrier doesn't protect your hypothalamus. And the reason for that is because your hypothalamus needs to be exposed to your bloodstream so that it can monitor the chemical makeup and the temperature of your blood in order to help maintain homeostasis. So your hypothalamus has a huge role in homeostasis so it needs to be exposed to the bloodstream so it can kind of monitor those different things in your bloodstream in order to maintain homeostasis, so that's very important. So this lesson has been an overview on the brain's three regions as well as it's protective barriers.
A barrier created by a glial cell called astrocytes; the blood-brain-barrier only allows a small amount of materials from the blood to enter the inside of the brain; plays a role in protecting neurons and creating a stable environment inside of the brain.
A fluid similar to plasma that is created by the brain; it washes the internal brain of metabolic waste and plays a minor role in cushioning the brain.
The protective connective tissue found on the outside of the brain and spinal cord; consists of three layers: dura mater, arachnoid mater, pia mater.
The largest part of the brain that consists of the cerebral hemispheres and all of the structures contained within them.
The area of the brain that connects the hindbrain to the forebrain; also the top structure of the brain stem.
The area of the brain that consists of the cerebellum, pons, and medulla oblongata.