They are the basic components of the nervous system.
These specialized cells are the information processing units of the brain responsible for receiving and transmitting information. Each part of the neuron plays a role in communicating information throughout the body.
Neurons carry messages throughout the body, including sensory information from external stimuli and signals from the brain to different muscle groups in the body.
To understand exactly how a neuron works, it is important to look at each individual part of the neuron. The unique structures of the neuron allow it to receive and transmit signals to other neurons, as well as other types of cells.
The parts of neurons are:
Dendrites serve as the input region of the neuron and receive information from other cells .
Dendrites are arborescent extensions at the beginning of a neuron that help increase the surface area of the cell body. These tiny bumps receive information from other neurons and transmit electrical stimulation to the soma. The dendrites are also covered in synapses.
- Most neurons have many dendrites.
- However, some neurons can have only one dendrite.
- Many are short and highly branched.
- It transmits information to the cell body.
Most neurons have these branch-like extensions that extend outward from the cell body. These dendrites then receive chemical signals from other neurons, which are then converted into electrical impulses that are transmitted to the cell body.
Some neurons have short, very small dendrites, while others have very long cells. Neurons in the central nervous system have very long and complex dendrites that then receive signals from up to a thousand other neurons.
If the electrical impulses transmitted into the cell body are large enough, they will generate an action potential. This results in the signal being transmitted down the axon.
The soma, or cell body, is where the signals from the dendrites come together and transmit. The soma and the nucleus do not play an active role in the transmission of the neuronal signal. Instead, these two structures serve to maintain the cell and keep the neuron functional.
Characteristics of soma
- It contains numerous organelles that are made primarily of endoplasmic reticulum.
- It contains a cell nucleus that produces RNA that supports important cellular functions.
- Supports and maintains the functioning of the neuron.
Think of the cell body as a small factory that powers the neuron. The soma makes the proteins that the other parts of the neuron, including dendrites, axons, and synapses, need to function properly.
The supporting structures of the cell include mitochondria, which provide energy for the cell, and the Golgi apparatus, which packages products created by the cell and secretes them outside the cell wall.
The axon mound is responsible for neuronal firing.
The axon mound is at the end of the soma and controls the firing of the neuron. If the total intensity of the signal exceeds the axon threshold limit, the structure will fire a signal (known as an action potential) down the axon.
The axon mound acts as a kind of manager, summing up the total excitatory and inhibitory signals. If the sum of these signals exceeds a certain threshold, the action potential will skyrocket and an electrical signal will be transmitted along the axon away from the cell body.
This action potential is caused by changes in ion channels that are affected by changes in polarization.
In a normal resting state, the neuron has an internal polarization of approximately 70 mV. When the cell receives a signal, it causes sodium ions to enter the cell and reduce polarization.
If the axon mound depolarizes to a certain threshold, an action potential will fire and transmit the electrical signal through the axon to the synapses.
It is important to note that the action potential is an all or nothing process and that the signals are not partially transmitted. Neurons either fire or not.
The axon transmits information away from the body of the cell.
The axon is the elongated fiber that extends from the cell body to the terminal endings and transmits the neuronal signal. The larger the axon, the faster it transmits information.
Some axons are covered with a fatty substance called myelin that acts as an insulator. These myelinated axons transmit information much faster than other neurons.
- Most neurons have only one axon.
- They transmit information away from the cell body.
- It may or may not have a myelin coating.
- Axons can vary dramatically in size.
The myelin that surrounds the neurons protects the axon and helps the speed of transmission.
The myelin sheath is divided by points known as the Ranvier rank nodules or myelin sheath. Electrical impulses can jump from one node to the next, which plays a role in speeding up the transmission of the signal.
Axons connect to other cells in the body, including other neurons, muscle cells, and organs. These connections occur at junctions known as synapses. Synapses allow electrical and chemical messages to be transmitted from the neuron to other cells in the body.
Terminal and synapse buttons
The terminal buttons are located at the end of the neuron and are responsible for sending the signal to other neurons. At the end of the terminal button is a space known as a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons.
The terminal buttons contain vesicles that contain neurotransmitters. When an electrical signal hits the terminal buttons, neurotransmitters are released into the synaptic space.
Terminal buttons essentially convert electrical impulses into chemical signals. Neurotransmitters that cross the synapse where they are then received by other nerve cells.
The terminal buttons are also responsible for the reuptake of any excess neurotransmitter released during this process.