Nerve impulses appear in neurons. They quickly move along the axon and act on other cells. Nerves are bundles of fibers (axons) of sensory and motor neurons. The fibers are surrounded by a dense connective tissue. The speed of the impulses along the nerve fiber is 2 meters per second, and even 120. Everything depends on the properties of the fiber. Nervous centers. Nerve cells are not scattered in the skin of the brain, but form clusters. These clusters are called the “gray matter” of the brain. Different clusters of nerve cells solve different problems: some process visual information, others – control movements, and others – are associated with the ability to read and write.
Cerebral cortex is a layer of gray matter up to 5 mm thick. It covers the surface of the cerebral hemispheres with their convolutions. It is there the mechanisms responsible for higher mental properties are located: thought, memory, speech.
Information processing in the brain
Impulses from receptors along the long processes of sensitive neurons come to the central nervous system. There, impulses act on intermediate neurons, those act on others, others act on others, and so on. Eventually, impulses come to the motor neurons. They are innervated: the motor neurons send impulses to the muscles along the nerves, the muscles contract; neurons, which control the glands, induce them to produce a secretion (substance), for example, saliva. Billions of neurons in the central nervous system affect each other so that the actions of the organism proceed correctly “by themselves.” We do not think how to take a breath, how to step.
for free
Reflex is a response action (reaction) of the body to signals from the surrounding world (including signals from your own muscles, heart, stomach).
Each reflex is performed with the involvement of the nervous system. For example, when the hand touches the fire and pulls back – this is a reflex. But the blister from a burn is not a reflex, although it is also a reaction of the body.
Neurovegetative system
In the spinal cord and the brain there are centers whose neurons control the work of the internal organs: accelerate or slow down the heartbeats, dilate or narrow the pupil of the eye, and so on. These are the centers of the autonomic nervous system. “Commands” that give such neurons are not subject to the will of man: it is impossible to order the heart: “Slow down!” Man’s behavior, his actions – is much more complicated than pulling his hand away from the hot objects. But the consciousness of man, his will, memory – are determined by the work of neurons.
Researchers of the nervous system
Ivan Mikhailovich Sechenov (1829-1905) discovered the phenomenon of inhibition in the central nervous system: it turned out that some neurons can stop the work of others.
Ivan Petrovich Pavlov (1849-1936) studied how the nervous system “operates” digestion. He investigated the mechanisms of behavior of animals and proved that, in addition to congenital reflexes, there are also those that are formed during life. He called them “conditioned” reflexes.
