Biology / Neuroscience · BEGINNER LESSON
Neuron
A neuron is a specialized cell of the nervous system that receives and sends information. It usually has a cell body, dendrites that receive input, and an axon that carries signals to other cells.
What a neuron is and what is measured
A neuron is the basic functional unit of the nervous system. In simple terms, it is a cell that receives information from other cells and transmits information onward, helping the body respond to internal and external changes. What is commonly described in neurons includes their shape, the parts of the cell, and how signals move from dendrites through the cell body and axon to axon terminals. [2]
[3] Information about the Brain - NIH Curriculum Supplement Series
Main parts and how they work
A typical neuron has a cell body, also called the soma or perikaryon, plus dendrites and an axon. Dendrites are the main receiving branches, while the axon carries the nerve impulse away from the cell body toward target cells. The axon often branches near its target and ends in synaptic regions, where it can contain vesicles, which are small membrane sacs that store materials for release. [0,1,2]
[1] Characteristics of the Neuron - Basic Neurochemistry - NCBI ... [2] Characteristics of the Neuron - Basic Neurochemistry [3] Information about the Brain - NIH Curriculum Supplement Series
Signal movement and synapses
Information normally moves in one direction inside a neuron: from dendrites, to the cell body, to the axon, and then to axon terminals. At a synapse, which is the junction between cells, the sending cell is presynaptic and the receiving cell is postsynaptic. The sources describe synapses as points of specialized contact and note that their effects can be excitatory, inhibitory, or modulatory. [0,2]
[1] Characteristics of the Neuron - Basic Neurochemistry - NCBI ... [3] Information about the Brain - NIH Curriculum Supplement Series
Myelin and fast conduction
Many axons are covered by myelin, a spirally wrapped membrane laid down in segments by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system. In myelinated fibers, sodium channels are concentrated at nodes of Ranvier, which supports rapid saltatory conduction, meaning the signal appears to jump from node to node. [0]
[1] Characteristics of the Neuron - Basic Neurochemistry - NCBI ...
Limitations and variation
Neurons are highly varied, so they are difficult to classify precisely by shape, location, function, or transmitter substance. Mature neurons usually do not divide, and the sources note that neuronal populations are largely established shortly after birth. Neurons also differ in whether they are excitatory, inhibitory, or modulatory, and in whether they have motor, sensory, or secretory roles. [0,1]
[1] Characteristics of the Neuron - Basic Neurochemistry - NCBI ... [2] Characteristics of the Neuron - Basic Neurochemistry
SEE THE IDEA
How a neuron handles information
Receive input from other cells
Integrates incoming information and contains organelles
Carries the impulse away from the cell body
Transfers information to a next cell across a tiny gap
Input is received by dendrites, passes through the cell body, travels down the axon, and reaches a synapse to influence another cell.
A neuron is organized for directed information flow from receiving branches to sending terminals.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
Drag a label onto its description, or select a label and then select a description. This also works with a keyboard.
4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.