Nervous tissue: structure and function.

We often nervous, constantly filter the incoming information, respond to the world around us and try to listen to your body, and in all this we are helped by the amazing cells.They are the result of a long evolution, the result of the work of nature throughout the development of organisms on Earth.

We can not say that our system of perception, analysis and response is ideal.But we are very far removed from the animals.Understand how such a complex system, it is very important not only for specialists - biologists and physicians.This may be interested in, and people of other professions.

information in this article is available to everyone and can benefit not only as knowledge, because of its understanding of the body - the key to understanding yourself.

What it meets

human nervous tissue has a unique structural and functional diversity of neurons and their specific interactions.After all, our brains - very difficult arranged system.And to control our behavior, emotions and thinking, we need a very complex network.

nervous tissue structure and function that defines a set of neurons - cells with processes - and cause the normal functioning of the body, first of all, provides the coordinated activity of all organ systems.Secondly, it connects the body to the external environment and provides an adaptive response to its change.Third, control of metabolism under varying conditions.All kinds of nerve tissue is a material component of the psyche: signaling systems - speech and thinking, characteristics of behavior in society.Some scientists have hypothesized that people greatly developed his mind, for he had to "donate" many animals are capable of.For example, we do not have keen eyesight and hearing, what can boast animals.

nervous tissue structure and functions which are at the heart of the electrical and chemical transmission is clearly localized effects.In contrast, humoral, this system works instantly.

Many small transmitters

cells of the nervous tissue - the neurons - are structural and functional units of the nervous system.Neuron cell characterizes the difficult structure and increased functional specialization.The structure of the neuron consists of eukaryotic body (soma) with a diameter of 3-100 microns and processes.Soma neuron contains a nucleus and nucleolus with the apparatus of biosynthesis which forms enzymes and substance inherent in the specialized functions of neurons.This calf Nissl - tightly adjacent to each other flattened cisterns of rough endoplasmic reticulum and Golgi apparatus developed.

functions of nerve cells can be continuously carried out, thanks to the abundance in the body "power plants" that produce ATP - hondrasom.The cytoskeleton submitted neurofilaments and microtubules play a supporting role.While the loss of membrane structures lipofuscin pigment is synthesized, the number of which increases with age neuron.The stem neurons formed pigment melatonin.The nucleolus is composed of protein and RNA from the DNA core.The ontogeny of the nucleolus and basophils determine the primary behavioral reactions in humans, since they depend on the activity and frequency of contacts.Nervous tissue involves the basic structural unit - the neuron, but there are also other types of support tissue.

avilable nerve cells

Dvuhmembrannoe nucleus neurons has pores through which penetrate and output waste substances.Through genetic apparatus is a differentiation, a configuration causes and frequency of interactions.Another function of the nucleus is the regulation of protein synthesis.Mature nerve cells can not divide by mitosis, and genetically determined active products of synthesis of each neuron must ensure the functioning and homeostasis throughout the life cycle.Replace damaged or missing parts can occur only intracellularly.But there are exceptions.The epithelium of the olfactory analyzer ganglia some animals are able to divide.

cells of the nervous tissue is visually distinguished by a variety of sizes and shapes.Neurons are inherent in irregular shape because processes are often numerous and overgrown.This - live conductors of electrical signals, which are composed by reflex arc.Nervous tissue, structure and functions of which depend on highly differentiated cells, whose role is in the perception of sensory information, coding it by means of electrical impulses and transfer the rest of the differentiated cells, is able to provide a response.She almost immediately.However, certain substances including alcohol, it slows down.

About axons

All kinds of nervous tissue function with direct participation processes-dendrites and axons.Axon translated from Greek as "axis".This extended process of conducting the excitement of the body to other neurons spikes.The tips of axons are highly branched, everyone is able to interact with neurons and form 5000 to 10 thousand contacts.

Locus soma, from which branches off the axon, called the axon hillock.It integrates with the axon that they lack the rough endoplasmic reticulum, RNA and the enzyme complex.

little about dendrites

This cell name means "tree."Like the branches of catfish grow stubby and strongly branching processes.They receive signals and serve as loci where synapses occur.Dendrites via side branches - spines - increase the surface area and therefore contacts.Dendrites without covers, the axons are surrounded by a myelin sheath.Myelin is a lipid nature, and its action is similar to the insulating properties of the plastic or rubber coating electric wires.Point generating excitement - the axon hillock - occurs in the place of origin of the axon from the soma in the trigger zone.

white matter ascending and descending pathways in the brain and spinal cord axons form through which nerve impulses are conducted, performing the function of the introducer - transmission of nerve impulses.Electrical signals are transmitted to the various departments of the brain and spinal cord, carrying out communication between them.The executive bodies at the same time can be connected to the receptors.Grey matter is formed by the cerebral cortex.The spinal canal is the center of innate reflexes (sneezing, coughing) and autonomic centers reflex activity of the stomach, bladder, bowel movements.Intercalary neurons, body and dendrites of motor reflex functions performed by implementing motor reactions.

especially the nerves tissue caused by a number of processes.The neurons are unipolar, psevdounipolyarnymi, bipolar.Nervous human tissue does not contain a unipolar one outgrowth of neurons.In the multipolar - an abundance of dendritic trunks.This branching does not affect the speed of the signal.

different cells - a variety of tasks

functions of nerve cells carry different groups of neurons.Specialization in the reflex arc or distinguish afferent sensory neurons, conducting impulses from the organs and skin to the brain.

intercalary neurons, or association, - a group of switching or connecting neurons that analyze and make a decision, carrying out the function of nerve cells.

efferent neurons, or sensitive, hold information about feelings - impulses from the skin and internal organs to the brain.

efferent neurons, effector, or motor, conduct impulses - "command" from the brain and spinal cord to all working bodies.

Features nerve tissue that neurons perform complex and jewelry work in the body, so humdrum primitive work - provision of food, removal of decay products, the protective function gets support cells or glia supporting Schwann.

The formation of nerve cells

The cells of the neural tube and the plate is differentiated ganglion, which determines the characteristics of nerve tissue in two ways: large become neuroblasts and neurocytes.Smaller cells (spongioblasty) do not increase and become glial cells.Nervous tissue types of fabrics which are composed neurons consists of main and auxiliary.Supporting cells ("gliocytes") have a special structure and funktsii.Tsentralnaya nervous system is represented by the following types of glial cells: ependimotsitami, astrocytes, oligodendrocytes;peripheral - gliocytes ganglia end neyrolemmotsitami and glial cells - Schwann cells.Ependimotsity line the cavity of the ventricles of the brain and the spinal canal and secrete cerebrospinal fluid.Types of nerve tissue - astrocytes, star-shaped formed fabric gray and white matter.The properties of the nervous tissue - astrocytes and glial membrane contributes to the creation of blood-brain barrier: the connection between the liquid and nerve tissue takes structural and functional boundaries.

Evolution fabric

basic property of a living organism is irritability or sensitivity.Type of nervous tissue justified phylogenetic position of the animal and has a broad variability, complicating the process of evolution.All organisms require certain parameters internal coordination and regulation, good interaction between the incentive to homeostasis and physiological state.Nervous tissue of animals, especially multicellular structure and functions have undergone aromorphoses promotes survival in the struggle for existence.Primitive hydroid presented stellate, nerve cells scattered throughout the body and connected the finest processes, intertwined.This type of nerve tissue called diffuse.

nervous system of flat and round worms stem, ladder (orthog-) consists of a pair of cerebral ganglia - clusters of nerve cells and the waste from these longitudinal shafts (konnektivy) interconnected strands cross-commissures.In annelids from peripharyngeal ganglion connected strands off the ventral nerve cord, in each segment of which - two contiguous nerve node connected by nerve fibers.Some soft-bodied concentrated nerve ganglia to form the brain.Instincts and orientation in space arthropods determined cephalization paired ganglia of the brain, nervous peripharyngeal ring and ventral nerve cord.

have chordate neural tissue, tissue types which are severe, difficult to find, but such a structure evolutionarily justified.Different layers occur and are located on the dorsal side of the body in the form of neural tube cavity - nevrotsel.In vertebrates is differentiated in the brain and spinal cord.In the formation of the brain at the front end of the tube blistering.If the lower metazoans nervous system plays a purely bridging role, then the higher animals made information storage, removing, if necessary, and also provides processing and integration.

In mammals, the brain give rise to blisters major parts of the brain.And the rest of the tube forms the spinal cord.Nervous tissue structure and function in higher mammals which its has undergone major changes.This progressive development of the cerebral cortex, and all parts of the nervous system, causing a complex adaptation to environmental conditions and the regulation of homeostasis.

Centre and Periphery

of the nervous system are classified according to functional and anatomical structure.The anatomical structure is similar to the place names where the isolated central nervous system and peripheral.The central nervous system includes the brain and spinal cord, and peripheral nerves shows, assemblies and terminations.Nerves presents accumulations processes is the central nervous system, myelin sheath covered general, conduct electrical signals.The dendrites of sensory neurons form the sensory nerves, the axons - the motor nerves.

totality of the long and short forms sprouts mixed nerves.Accumulating and concentrating, the bodies of neurons constitute nodes beyond the central nervous system.Nerve endings are divided into receptor and effector.Dendrites by the terminal branches are converted into electrical signals irritation.And the end of the efferent axons - in the working bodies, fibers, muscles, glands.Classification functionality implies the division of the nervous system in the somatic and autonomic.

Something we control, but something beyond our control

properties of nerve tissue due to the fact that the somatic nervous system is subject to the will of man, innerviruya operation support system.Motor centers are located in the cerebral cortex.Autonomy, which is also called vegetative, does not depend on the will of man.On the basis of your own queries, you can not speed up or slow heartbeat, or intestinal motility.Since the location of the vegetative centers - the hypothalamus via the autonomic nervous system supervises the work of the heart and blood vessels, the endocrine system, abdominal organs.

nervous tissue, photos which you can see above, forms the sympathetic and parasympathetic divisions of the autonomic nervous system, which allows them to act as antagonists, providing mutually antithetical effect.Excitation in one body is inhibitory processes in the other.For example, the sympathetic neurons causes a strong and frequent contraction of the heart chambers, vasoconstriction, blood pressure jumps as norepinephrine is released.Parasimpatika releasing acetylcholine, helps to reduce heart rate, increase in the lumen of the arteries, lowering the pressure.Balancing these groups of mediators normalize heart rhythm.

sympathetic nervous system acts during intense stress when frightened or stressed.The signals occur in the area of ​​the thoracic and lumbar vertebrae.The parasympathetic system is activated at rest and digestion, during sleep.The bodies of the neurons - in the trunk and sacrum.

further explore characteristics of Purkinje cells, which are pear-shaped with many branching dendrites, you can see how the momentum transfer, and reveal the mechanism of the successive stages of the process.