hey guys in this video we'll be looking at the nervous system we are going to cover the human brain as well as the spinal cord let's get to the lesson when we think about the nervous system the first thing we are drawn to is the brain the brain is truly a remarkable organ it contains over 100 billion neurons the nervous system is branched into two that is the central nervous system in the peripheral nervous system what you're looking at in this diagram is only the central nervous system and so we would recognize this organ here as the brain and then connected to the brain at the bottom here this part that stems out of the brain is known as the spinal cord together the brain and the spinal cord form the central nervous system the shot for this is the cns we also have nerves coming out of the central nervous system as you can see the central nervous system is positioned at the center of the body but we all know that we have neurons at the tip of our fingers at uh tip of our noses and our toes so where are all these nerves coming from these all stem out from the central nervous system so when it is in the head or inside the cranium the cranium is the top part of the skull so any nerve inside the head here these nerves are collectively called the cranial nerves we also have lots of nerves that stem out of the spinal cord many many nerves coming out of the spinal cord these nerves that come out of the spinal cord are known as the spinal nerves together the cranial nerves and the spinal nerves since they are located at the periphery of the body on the sides together they form the peripheral nervous system so this is the large classification of the nervous system we have the central nervous system which is made of the brain and the spinal cord and then we have the peripheral nervous system that is made of the cranial nerves and the spinal nerves the peripheral nervous system is further divided into two under the peripheral nervous system we have the somatic nervous system and the autonomic nervous system as the name would suggest the autonomic nervous system is responsible for involuntary actions these are actions that you do not consciously control such as the movement of food through your digestive tract the contraction of your heart muscles these are controlled by the autonomic nervous system whereas the somatic nervous system is involved in controlled actions let's take a closer look at the brain this is what the human brain looks like if you look at the largest portion of the brain that would be this part here on the outside this large portion of the brain is known as the cerebrum and the cerebrum is involved for voluntary actions so we have things such as sight hearing our emotions personality control actions the cerebrum is also responsible for what you are doing right now that is higher mental abilities such as learning thinking memorizing linguistic skills as well as mathematics skills so you can see the cerebrum is responsible for what we are doing consciously everything that we are doing consciously is processed by this server speaking about learning and controlled actions if you're getting anything from this video guys please do me a favor hit that like button really does help the channel thank you very much for doing that let's move on now what about the things that we do unconsciously the things that we do unconsciously is controlled by this tiny part here along the brainstem here this is called the medulla oblongata the medulla oblongata is responsible for involuntary actions involuntary actions are such as sneezing coughing the heartbeat peristalsis that is movement of the foot along the digestive tract vomiting these are things that we cannot control and we wouldn't want to control as well imagine if you are responsible for your own heartbeat how scary would that be but the medulla oblongata takes care of all of that for us we don't have to worry about any of that it's also responsible for breathing breathing imagine if we have to control our own breathing that would be a pretty heavy responsibility swallowing vascular constriction vasoconstriction is the narrowing of the blood vessels these are all the very general things the control actions by the cerebrum and the involuntary actions by the media of nagata but there's much more to what we are as human beings here at the back just below the cerebrum this one here if you look at it from the outside normally you will see there's a lot of sort of wrinkles here this is the cerebellum and the cerebellum is very important for body balance the balance of our body the fact that i can sit up straight right now is because of the function of my cerebellum the cerebellum coordinates muscle movement it is responsible for the coordination of all our muscle contraction the fact that i want to move my hands like this the coordination of my movements in this specific manner is processed by the cerebellum other instances include riding a bicycle for example or riding a motorcycle body balance is crucial there and this is where the cerebellum comes into play so as you can see we've already covered most of the brain however there's this part right here this part here in the middle this is known as the hypothalamus although it's a very small part it has a very crucial role the hypothalamus remember h and h hypothalamus is responsible for homeostasis homeostasis is a whole other topic when i do a video on that i'll leave the link in the description below generally homeostasis is the maintenance of a steady internal environment what internal environment are we talking about for example body temperature our body temperature needs to be maintained at 37 degrees celsius for our cells to function optimally because everything that goes on in the body is controlled by biochemical reactions which involves enzymes therefore we need it to be at a very specific temperature for the enzymes to function optimally so this is homeostasis and this involves body temperature regulation water balance regulation blood sugar pressure regulation so these things are all controlled by the hypothalamus hypothalamus has other functions as well such as sensing hunger this and fatigue and one of the very important roles of hypothalamus is that it actually connects to the endocrine system in coordination and response both the nervous system and the endocrine system are involved and the link between the two is actually the hypothalamus the hypothalamus is linked to the endocrine system through the next organ in the brain and that is this tiny lie right here this is the pituitary gland the pituitary gland is known as the master gland of the endocrine system this is because the pituitary gland actually releases hormones that controls the other endocrine glands in the endocrine system the endocrine system consists of glands that releases hormones i've done a video on that in depth i'll leave the description in the link below you can go and check that out the organ that controls the pituitary gland is the hypothalamus in fact the hypothalamus actually has neurons going into the posterior pituitary so what happens is the hypothalamus secretes certain hormones that is adh and oxytocin i covered that in depth in the video below these hormones actually are separated into the posterior pituitary gland which is then secreted into the blood these are the different parts and functions of the brain now let's go to the spinal cord this is a cross section of the spinal cord when we look at the spinal cord immediately you will notice a hitch or butterfly shape in the middle this is the gray matter the gray matter is a collection of cell bodies in the center of the spinal cord and then outside of that you can see white matter this is the white matter surrounding the gray matter when you look at the cross section of the spinal cord you can see that there are parts that are coming out of the center such as this and this these are known as the roots we have the same thing on both sides it is symmetrical but these are known as the roots and the root naming of the roots depends on their position if they are at the back these these two are at the back so these are known as the dorsal roots the ones at the back and the ones in front here are called the ventral roots so we have the dorsal and ventral group and the dorsal root inside the dorsal root if we look at this one here this is where we have this neuron you can see there's a neuron inside the root and this neuron if you notice the cell body is in the middle therefore this is a sensory neuron i will cover neurons in another video as well so sensory neuron is contained in the dorsal group and the role of the sensory neuron is to send nerve impulses from our receptors sensory receptors to the spinal cord you can see it terminates here at this position this is the role of the sensory neuron which is contained in the dorsal root and then in the middle here we have the interneuron so cover neurons in a separate video and after that in the ventral root you can see we have another neuron in this neuron you can see the cell body is at the end and the cell body is at the end then you can tell that this is a motor neuron the motor neuron is contained in the ventral group as you can see and the role of the motor neuron is to carry information from the spinal cord to the e factor that is the organ that is going to carry out the response this is the ventral root if we look along the dorsal root you will see that a certain part here bulges out and the bulge in the dorsal root is due to the cell body of a sensory neuron this bulge has a special name and that is called the dorsal root ganglion and the dorsal root ganglion is just a collection of the cell bodies all the cell bodies clustered together causing there to be a bunch if you look beyond the roots both the roots merge at this point the roots merge at this point and this is where it comes out as what we saw very beginning of the video the spinal nerve so the spinal nerve that comes out of the spinal cord actually consists of the sensory neuron as well as the motor neuron because they are both combined here in this place that's it for this video guys i hope you've learned something if you have please do hit that like button thank you very much really just help the channel if you enjoy videos like this do subscribe i'll be producing at least one video a week see you guys in the next video