Nerve cells are also called neurons. It consists of three parts which are as follows:. Cell Body - It contains the nucleus and other cell organelles. It is also known as soma the factory of the neuron. It provides and produces all the proteins for the dendrites, axons and synaptic terminals. Dendrites - These are extended from the cell body and receive nerve impulses from other neurons. Dendrites are the antennae of the neuron and covered by a large number of synapses.
Axon - It is a long extension of the cell body that transmits nerve impulses to other cells. The branches of the axon at the terminal are known as axon terminals. At these terminals, neurons communicate with other cells. Myelin sheath is present in the axon of many neurons as an outer layer.
It is a part of the motor neuron. The basic principle on which a neuron works is an electrically excitable cell that takes up processes and transmits information through electrical and chemical signals. With this, human beings can react to the environment as neurons transport stimuli. As all neurons are electrically excitable, the impulse mostly arrives at dendrites which are processed into the cell body and then move along the axon.
Neurons can be quite large - in some neurons, such as corticospinal neurons from motor cortex to spinal cord or primary afferent neurons neurons that extend from the skin into the spinal cord and up to the brain stem , can be several feet long! Types of Neurons Nerve Cells The human body is made up of trillions of cells.
Neurons are similar to other cells in the body because: Neurons are surrounded by a cell membrane. Neurons have a nucleus that contains genes. Neurons contain cytoplasm, mitochondria and other organelles. Neurons carry out basic cellular processes such as protein synthesis and energy production. However, neurons differ from other cells in the body because: Neurons have specialize cell parts called dendrites and axons. Dendrites bring electrical signals to the cell body and axons take information away from the cell body.
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.
The longest axon in the human body extends from the bottom of the spine to the big toe and averages a length of approximately three feet!
How do neurons transmit and receive information? In order for neurons to communicate, they need to transmit information both within the neuron and from one neuron to the next. This process utilizes both electrical signals as well as chemical messengers.
The dendrites of neurons receive information from sensory receptors or other neurons. This information is then passed down to the cell body and on to the axon. Once the information has arrived at the axon, it travels down the length of the axon in the form of an electrical signal known as an action potential.
Once an electrical impulse has reached the end of an axon, the information must be transmitted across the synaptic gap to the dendrites of the adjoining neuron. In some cases, the electrical signal can almost instantaneously bridge the gap between the neurons and continue along its path.
In other cases, neurotransmitters are needed to send the information from one neuron to the next. Neurotransmitters are chemical messengers that are released from the axon terminals to cross the synaptic gap and reach the receptor sites of other neurons. In a process known as reuptake, these neurotransmitters attach to the receptor site and are reabsorbed by the neuron to be reused. 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. Alzheimer's disease: Targeting the cholinergic system. Curr Neuropharmacol. Prefrontal dopamine signaling and cognitive symptoms of Parkinson's disease.
Rev Neurosci. Front Psychiatry.
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