They are cells that transmit information throughout the system. Neurons are composed of cell bodies, dendrites, and axons. The cell body is the spherical part of a neuron that contains the nucleus. It can also be called the soma. Cell bodies connect to dendrites, which is what brings information to the cell body. Cell bodies also connect to axons, which is what sends information from the cell body to other neurons.
There are three types of neurons. Sensory neurons, Motor neurons, and interneurons. All of them contain cell bodies, dendrites and axons, but some also have myelin sheaths, which is what covers the axon and helps speed neural impulses.
These impulses are electrochemical signals that are called Action Potential, which is a brief electrical charge that goes down an axon and is caused by positive ions moving in and out of the axon. When more positives ions are outside of the axon, this is called “Resting Potential.” When an incoming message stimulates a section of the axon, this is called depolarization. Channels in the membrane will open to allow Na+ ions to enter the axon. “Repolarization” Is when channels open and allow K+ ions to exit the axon, and cases the next segment of the axon to depolarize.
“Glial cells” are cells that provide structural, nutritional, and other support for the neuron. “Nodes of Ranvier” are spaces between Shwann cells that wrap around the axon.
When a signal reaches the end of an axon, the signal is then sent to the next neuron in the network. This is called a Synapse. A synapse includes the tips of terminal branches of axons, tiny space between the neurons, and the ends of dendrites of the receiving neurons. Proper brain and nervous system functions depend on proper balance of excitatory and inhibitory Neurotransmitters. NT Disruptors are what fit into receptors like a key in a lock, and stop other molecules from fitting. Examples of these are Black widow spider venom and nicotine. Nicotine is an agonist as well, which is a molecule that has a very similar shape to acetylcholine, and mimic the action of it. Antagonists are what block NT from binding to the receptor. Snake venom is an example of this and causes paralysis of the muscles.