Nervous System: The nervous system is made up of the brain, spinal column, and peripheral nerves and is used to send messages to the muscles of the body and receives them. The nervous system also provides sense of touch.

Central and Peripheral Nervous System Central Nervous System – made up of brain and spinal cord; functions as the command center of the nervous system Peripheral Nervous System – made up of any nerve which is not the brain or the spinal cord.

Simple Reflex Arc

Cerebral Hemispheres

Parts of the Brain

Neural Communication Ion pumps in the cell membranes of neurons release three positively charged sodium ions, while taking in only two positively charged potassium ions which creates a negative charge inside the cell. The space inside the neuron now has a resting potential, which is a kind of membrane potential, because it has a more negative charge inside the cell then outside the cell, and cells always try to achieve homeostasis. When stimulated, the neuron has action potential, which is a spike in energy in the cell, and happens so the neuron can communicate with other neurons, muscle cells, or glands. The peak of this process is called the threshold and it acts as the climax of the energy. There is a brief period after the neuron has fired is called the refractory period in which the muscles or neurons cannot respond to the neurons stimulation. The renewal of homeostasis when the charge outside the neuron is balanced with the charge inside, is called depolarization. After the refractory period has passed, the system will then begin again to ready the neuron to fire again.

Postsynaptic Potential IPSP – Inhibitory Postsynaptic Potential: Inhibits the chances that action potential will be reached EPSP – Excitatory Postsynaptic Potential: Increases the chances that action potential will be reached

Parkinson’s Disease When someone has Parkinson’s, part of the brain releases dopamine and the dopamine causes random neurons to fire, causing the person to lose control of their body. Symptoms: -shaking of the appendages and face -sluggish movement -stiffness -poor coordination and balance Approximately 10 million people around the world are living with Parkinson’s About 60,000 cases are diagnosed in the United States alone There is currently no cure for Parkinson’s, but treatment is an option. Carbidopa is a popular drug that just suppresses some of the impulses.

Multiple Sclerosis When the immune system responds, it attacks the central nervous system instead of the virus, causing interruptions in neuron communication. Symptoms: -fatigue -numbed or changed sensations -difficulty moving -changes in vision About 2.3 million people are affected by MS worldwide No cure is yet available for MS, but there are treatment options. They attempt to reduce inflammation of the areas that are blocking neural communications to lessen the symptoms.

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