The cell body contains the nucleus and cytoplasm. The axon extends from the cell body and often gives rise to many smaller branches before ending at nerve terminals.
Dendrites extend from the neuron cell body and receive messages from other neurons. Synapses are the contact points where one neuron communicates with another.
The dendrites are covered with synapses formed by the ends of axons from other neurons. Illustration by Lydia V. The brain is what it is because of the structural and functional properties of interconnected neurons. The mammalian brain contains between million and billion neurons, depending on the species. Each mammalian neuron consists of a cell body , dendrites , and an axon. When neurons receive or send messages, they transmit electrical impulses along their axons, which can range in length from a tiny fraction of an inch or centimeter to three feet about one meter or more.
Many axons are covered with a layered myelin sheath, which accelerates the transmission of electrical signals along the axon. This sheath is made by specialized cells called glia.
Neurons communicate with each other through an electrochemical process. Neurons contain some specialized structures for example, synapses and chemicals for example, neurotransmitters. The Neuron One way to classify neurons is by the number of extensions that extend from the neuron's cell body soma. Neurons can also be classified by the direction that they send information.
Sensory or afferent neurons: send information from sensory receptors e. Motor or efferent neurons: send information AWAY from the central nervous system to muscles or glands. Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system. Hear It "Neuron" "Axon" "Dendrite" "Nissl" "Mitochondria" "Endoplasmic reticulum" There are several differences between axons and dendrites: Axons Dendrites Take information away from the cell body Smooth Surface Generally only 1 axon per cell No ribosomes Can have myelin Branch further from the cell body Bring information to the cell body Rough Surface dendritic spines Usually many dendrites per cell Have ribosomes No myelin insulation Branch near the cell body What is inside of a neuron?
Nucleus - contains genetic material chromosomes including information for cell development and synthesis of proteins necessary for cell maintenance and survival. Covered by a membrane. Nucleolus - produces ribosomes necessary for translation of genetic information into proteins Nissl Bodies - groups of ribosomes used for protein synthesis.
Endoplasmic reticulum ER - system of tubes for transport of materials within cytoplasm. Can have ribosomes rough ER or no ribosomes smooth ER. With ribosomes, the ER is important for protein synthesis.
Golgi Apparatus - membrane-bound structure important in packaging peptides and proteins including neurotransmitters into vesicles. Mitochondria - produce energy to fuel cellular activities. Happy st Birthday to the Golgi apparatus!
In , the famous neuroanatomist Camillo Golgi reported his discovery of a ribbon-like apparatus inside neurons of the cerebellum. This structure now bears his name as the "Golgi apparatus.
Neurotransmitters are an essential part of our everyday functioning. While it is not known exactly how many neurotransmitters exist, scientists have identified more than of these chemical messengers.
The following are just a few of the major neurotransmitters, their known effects, and disorders they are associated with. Acetylcholine: Associated with memory, muscle contractions, and learning. Endorphins: Associated with emotions and pain perception. The body releases endorphins in response to fear or trauma. These chemical messengers are similar to opiate drugs such as morphine but are significantly stronger.
Dopamine: Associated with thought and pleasurable feelings. One category is dopamine agonists, which mimic the effects of dopamine. Another type of agent is levodopa, which is converted into dopamine in the brain.
They each carry their own relative benefits and side effects. Researchers also have found strong links between schizophrenia and excessive amounts of dopamine in certain parts of the brain. Ever wonder what your personality type means? Sign up to find out more in our Healthy Mind newsletter.
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Neuron Structure.
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