What Is a Nervus?

Nerves are composed of bundled nerve fibers, and the structure of the nerve fibers itself is covered by a myelin sheath formed by glial cells outside the axons of neurons.

[shén jng]

Nerves are gathered into bundles

Tissues composed of nerve fibers pass the excitement of the brain and spinal cord to various organs, or the excitement of each organ to the brain and spinal cord.

Walking into the village, the nerves were not as tense as at night, and the body was followed by fatigue.

1. It is a mysterious book. "The Preface to the Book of Later Han Dynasty · Fujitsu Biography": "Ran nerve strange, jade strategy golden rope, closed in the Ming Ling Mansion, sealed in the Yao altar, and peeked out." Tang Jing broadcast "Preface": " Quite a note, rather than the best of the earth and the earth;

2. Pass the excitement of the central nervous system to various organs, or the excitement of each organ to the tissues of the central nervous system. Made up of many nerve fibers. Chapter 7 of Ba Jin's "Destruction": "The sedation on the surface cannot hide the nervous tension and the inner fighting."

3. Refer to thoughts and ideas. Lu Xun's Collection of Letters to Zhou Zuoren: "The day before yesterday, Shen Yin Mo Shao introduced Zhang Huang, that is," Ukiyo-e ", this person is very good and clear-cut." ^[1]

According to the definition of physiological psychology, nerves are made up of neurons, and the whole system of neurons is called the nervous system. Neurons are the structural and functional units of the nervous system.

Neurons are substances at the physiological level, that is, special cells, may be called nerve cells. Aside from the specific differences between brain neurons, spinal neurons, and plant neurons, neurons are composed of cell bodies and processes. Nerve cell processes are divided into axons and dendrites. The longer processes of neurons are wrapped by myelin sheaths and nerve membranes to form nerve fibers. (If it is wrapped by myelin sheath and nerve membrane together, it is called myelinated nerve fiber. If it is only wrapped by nerve membrane, it is myelinated nerve fiber.) Nerve fibers are criss-crossed, and it is (neurons) that form a network of neurons (ie Neural), which has the function of information collection and transmission, which is manifested as psychological stimulation and response; the nerve cell body is the basic information storage and processing unit in the neuron; the information after preliminary processing is transmitted through the nerve fibers in layers, Until the brain nerve is reached, the final total processing is performed, and then the result of the processing is returned to the neuron, which is finally executed by the effector or gland to produce a physiological response.

Neuronal structures include cell bodies, dendrites, axons, myelin sheaths, Schwann cells, Langfie knots, and the like.

Schwann's cells appear in the peripheral nervous system, forming a myelin sheath to insulate the axons extended by neurons in the peripheral nervous system. The myelin sheath does not cover the entire axon. Leaving a gap, called the Lang's knot, speeds up the conduction of nerve signals in a jump-conduction manner.

Schwann cells have the ability to phagocytose, which can remove cell debris and provide space for neuron regeneration.

The material that surrounds the axons of neurons has interrupted sections at regular intervals, forming a section-by-section shape. The interrupted part is called "Ranvier's node". Myelin is formed by Schwann's cells or other types of neural support cells.

Myelin usually occurs only in axons of vertebrates.

Myelin has three functions: 1. Provides electrical insulation between axons and surrounding tissues, such as adjacent axons, to avoid interference; 2. Speeds up action potentials through a mechanism called "jumping conduction" Pass; 3. Guide regeneration of axons in the event of some axons being damaged.

The Nodes of Ranvier are part of a neuron, named after the first French scientist Louis-Antoine Ranvier to describe the structure [1].

The axon of the neuron is covered with myelin sheath, and the Lange nodule is the part without neuromyelin that appears every few millimeters on the neuron.

The theory of jump conduction holds that, because the resistance between the junctions between the Lang's junctions is extremely high and the resistance in the junctions is extremely low, and the axon membrane can only contact the extracellular fluid in the junctions, the local current must Lang Fei's nodule penetrates the membrane to form a loop at the myelin sheath and conducts jump conduction [2].

The reason why a neuron is a necessary condition for a nerve is that: within the nerve fibers, most of the information is transmitted by means of bioelectric pulses, but the nerve fibers of each neuron are not directly connected but separated by other substances On, such as acetylcholine and so on. This is actually a new structural level or link and will not be described in detail. When bioelectricity reaches between adjacent nerve fibers, it will be converted into a chemical signal, which will be transformed by a material carrier and then converted into an electrical signal. Therefore, a complete nerve includes not only different nerves such as the brain nerve, spinal nerve, and autonomic nerve, but also the intermediate chemical media.

Based on the above, we can draw the following conclusions:

From the perspective of material dependence of psychological phenomena, nerves can be defined as material (physical) realization of psychology, and psychology is the functional performance of nerves;

From the perspective of the relationship between nerves and neurons, nerves are a system composed of neurons and mediators;

From the perspective of physiology and psychology, the nerve is more precise than the concept of the nervous system;

Psychology is the function of nerves , not (only) the function of the brain ;

According to the above four points, relevant concepts in psychology need to be adjusted appropriately.