Health Nervous System

The Central Nervous System The combination of the brain and spinal cord together is the central nervous system. The largest part of the brain is called the cerebral cortex. The cerebral cortex controls thinking, remembering, and reasoning. It is located in the front area (frontal lobe), and along the surface going about two thirds of the way back on the top of the brain. This is a large part of the brain.

The Cerebellum The second largest part of the brain is called the cerebellum. It is located in the back of the brain, called the occipital lobe. The function of the cerebellum is balance and coordination.

The Medulla Oblongata The third largest part of the brain is a structure that is at the base of the brain called the medulla oblongata. This structure controls involuntary functions such as heart rate, kidney function, liver function, digestion, and respiration. What are involuntary functions?

Anatomy

The Peripheral Nervous System The central nervous system is the brain and spinal cord. The peripheral nervous system consists of all the nerves outside of the brain. These are the nerves in our arms and legs. Nerves that allow us to move and feel. These are a part of the peripheral nervous system.

CNS and PNS

The Neuron (The Nerve Cell) In the neuron, there are a variable number of structures called dendrites, which carry messages (Impulses) toward the cell body. In the neuron, there is one structure called an axon, which carries impulses away from the cell body. Between each nerve cell (neuron) is a small gap called a synapse. Impulses jump across this synaptic gap as they travel from neuron to neuron.

Axons and Dendrites There is one axon per neuron. The function of the axon is to send impulses out from the nerve cell. The number of dendrites per neuron varies. The function of the dendrite is to take impulses into the nerve cell. The junction between the axon and the dendrite is the synapse.

The Neuron, Cont. Unlike other cells in the body, nerve cells do not reproduce. They do not divide and produce more nerve cells. This means that whenever one neuron dies, that is the end of that neuron and no other one will be produced to replace it. This also means that if enough neurons die in the human brain, it will function at a decreased ability, this is senility. The over use (abuse) of alcohol increases the likelihood of senility, because alcohol kills neurons.

The Neuron

Neurotransmitters At the ends of the axon, there are bubble-like structures called vesicles. The vesicles hold chemicals called neurotransmitters. There are four neurotransmitters. They are: 1) Serotonin 2) Norepinephrine 3) Acetylcholine and 4) Dopamine

Cont. Serotonin relaxes us, and gives us a feeling of calm. It makes us “feel good.” “At peace with the world.” While serotonin makes us feel peaceful, norepinephrine makes us feel “happy.” A kind of excuberant, excited kind of happy. Like the last day of school kind of happy. Christmas kind of happy. Great report card kind of happy. Vacation kind of happy. Acetylcholine makes impulses travel a little slower across the synapse (space between two neurons). Dopamine helps make impulses travel a little quicker across the synaptic cleft.

The Synapse

Cocaine This is where cocaine works on people. What cocaine dose is it “forces” all of the norepinephrine out of the vesicles, into the synapse. Remember, normal amounts of norepinephrine makes us feel “really happy”. If all of the norepinephrine is forced to pour out, the feeling it will produce in the person is an artificial feeling of “fantastic”. Now the problem. When the norepinephrine wears off. There is no norepinephrine left. It was all used up. Now that there is no norepinephrine left to regulate normal amounts of happy feelings in the person. They now have feelings of terrible depression. Some people go back and take more cocaine than they originally took to try and feel better, overdosing. Some people commit suicide. Cocaine is a trap. Better to never take it at all. Avoid a lot of trouble.

The Brain (lobes) Lobes are areas or regions. There are four of them. Frontal lobe: As it states, this lobe is in the front of the brain. Temporal lobe: There are two of these. They are on the sides of the brain, by the ears. Parietal lobes. There are two of these also. They are located just above the temporal lobes. Occipital lobe. This covers the back of the brain.

The Lobes

Gyri and Sulci Have you ever noticed that when you see a picture of the brain, that it is covered with “wrinkles”. These wrinkles have a name. The grooves are called sulci, or sulcus for singular. In between each sulcus is the bulging out part called the gyrus (gyri for plural). The largest sulcus in the brain is the one that divides the brain into right and left “hemispheres”. This sulcus is called the longitudinal fissure.

Diseases (Pathology) of the Nervous System Tumor (Cancer) Cerebrovascular Accident (CVA), Stroke Alzhiemer’s Disease Concussion/ injury

Brain Stem Glioma

Fracture

Infiltrating Glioma

Subdural Hematoma

Tumor in Rt. Temp. Lang. Expressive Area

The End!