Dendrites are conductors of an electrical impulse.
consists of neurons (specific cells with processes) and neuroglia (it fills the space between nerve cells in the central nervous system). The main difference between the two is the direction of transmission of the nerve impulse. Dendrites arereceiving branches, for them the signal goes to the body of the neuron. Transmitting cells - axons - conduct a signal from the catfish to the receiver. It can be not only the processes of a neuron, but also muscles.
Types of neurons
Neurons can be of three types: sensitive - those that receive a signal from the body or the external environment, motor - transmitting impulse to organs, and intercalary, which interconnect two other types.
Nerve cells can differ in size, shape, branching and number of processes, axon length. Research results have shown that dendritic branching is larger and more complex in organisms that are higher on the steps of evolution.
Differences between axons and dendrites
What is the difference between them? Consider.
- The dendrite of the neuron is shorter than the transmitting process.
- There is only one axon; there may be many branches.
- The dendrites branch strongly, and the transmitting processes begin to divide closer to the end, forming a synapse.
- The dendrites become thinner as they move away from the neuron body, the thickness of the axons is almost unchanged along the entire length.
- The axons are covered with a myelin sheath consisting of lipid and protein cells. It acts as an isolator and protects the process.
Since the nerve signal is transmitted in the form of an electrical impulse, the cells need isolation. Its function is performed by the myelin sheath. It has the smallest breaks, contributing to faster signal transmission. Dendrites are shellless processes.
The place where the contact between the branches of the neurons or between the axon and the host cell (for example, muscle) occurs is called a synapse. Only one branch from each cell can participate in it, but most often contact occurs between several processes. Each outgrowth of an axon can come into contact with a separate dendrite.
The signal in the synapse can be transmitted in two ways:
- Electric. This happens only in the case when the width of the synaptic cleft does not exceed 2 nm. Due to such a small discontinuity, the impulse passes through it without stopping.
- Chemical.Axons and dendrites come into contact due to the potential difference in the membrane of the transmitting process. On one side of the particle has a positive charge, on the other - negative. This is due to the different concentrations of potassium and sodium ions. The first are inside the membrane, the second - outside.
With the passage of the charge, the permeability of the membrane increases, and sodium enters the axon, and potassium leaves it, restoring potential.
Immediately after the contact, the process becomes immune to signals, after 1 ms it is capable of transmitting strong pulses, after 10 ms it returns to its original state.
Dendrites arethe recipient transmitting impulse from the axon to the body of the nerve cell.
The functioning of the nervous system
The normal functioning of the nervous system depends on the transmission of impulses and chemical processes in the synapse. The creation of neural connections is equally important. The ability to learn is present in humans precisely because of the ability of the organism to form new connections between neurons.
Any new action at the study stage requires constant monitoring by the brain. As it is developed, new neural connections are formed, with time the action starts to be performed automatically (for example, the ability to walk).