All living things on Earth need information about the environment in which living organisms live, and man is no exception. The ability to obtain environmental information is provided by sensitive (sensory) systems. Any activity of the sensory system begins with the receptor perception of the stimulus energy and its transformation into nerve impulses, as well as the transmission of these impulses through the neural chain to the brain, which converts nerve impulses into specific sensations, for example, auditory, olfactory, visual, tactile and others.
What are human analyzers and sense organs? About it further.
About analyzers
During the study of the physiology of sensory systems, academician Pavlov I.P. created a work on analyzers. Each analyzer has three departments: central, peripheral and conductor.
The peripheral department is represented by receptors - nerve endings that have a sensitivity that is selective only to a certain type of stimulus. They are included in the sensory organs corresponding to them.
Analyzers and sense organs: their structure and functions
The analyzer has a typical structure. It consists of the receptor department, the conducting part and the central department. The receptor or peripheral part of the analyzer can be represented as a receptor. He perceives and performs the primary processing of certain information. For example, a sound wave is captured by an ear curl, light by the eye, pressure by skin receptors.
In the complex sensory organs (taste, vision, hearing), in addition to receptors, there are auxiliary structures that provide a good perception of the stimulus and perform supporting, protective and other functions. For example, the auxiliary structures of the visual analyzer are represented by the eyes, while the visual receptors are represented only by sensitive cells (cones and rods). We can distinguish external receptors that are located on the surface of the body and perceive irritations of the external environment, and internal receptors of the internal environment and organs of the body.
How are analyzers and sense organs arranged?
The conductor analyzer department is shown by nerve fibers that conduct nerve impulses to the central nervous system from the receptor (auditory, olfactory, optic nerve, and others).
The central section of the analyzer is a specific part of the cerebral cortex in which the synthesis and analysis of the provided sensory information and its transformation into specific sensations (olfactory, visual, and others) takes place.
A prerequisite for the normal operation of the analyzer can be called the integrity of all three of its departments. How do sense organs and analyzers work? About it below.
Visual analyzer
The receptor part of this structure is represented by the eyes. Chemical reactions here form an electrical impulse that passes through the optic nerve and projects into the occipital lobe of the cerebral cortex.
The work of the auditory analyzer. The receptor here is the ear. The external part is going to sound, the middle comes further. The signal moves along the auditory nerve to the brain, its temporal lobes.
The work of the olfactory analyzer. The olfactory epithelium covers the inner lining of the nose. Odor molecules are perceived by him, while nerve impulses are created.
The work of taste analyzers. They are represented by taste buds - sensitive chemical receptors that respond to chemicals.
There are also tactile, temperature, pain analyzers - also consist of receptors on the skin. Let us consider in more detail the concepts of “sensory organs” and “analyzers”.
Organ of vision
The largest amount of information about the outside world is transmitted to a person through the organ of vision, that is, the eye, which consists of an auxiliary device and the eyeball. The eyeball is located in the front of the skull in the orbit, and the upper and lower eyelids protect it from mechanical damage, as well as the eyelashes and protrusions of the frontal, nasal and zygomatic cranial bones.
Human analyzers and sense organs are unique.
In the upper outer eye corner is the lacrimal gland, which secretes tear fluid, a tear that facilitates the movement of the eyelids, and moistens the surface of the eyeball. In the inner corner, an excess of tears is collected, gets into the lacrimal canals, and then into the nasal cavity through the nasolacrimal duct. Six oculomotor muscles connect the eyeball and the bony walls of the orbit and allow movement down, up, to the sides.
Three membranes form the walls of the eyeball: fibrous (external), vascular (middle) and retina or reticular (internal). The outer membrane in the larger, posterior part forms the sclera (a dense white membrane), while in front it passes into a transparent membrane permeable to light, the cornea. The nucleus of the eye protects the sclera, and also retains its shape. The eye is fed by the blood vessels that the choroid is rich in. The iris, that is, its front, is pigmented, and this pigment determines the color that the eye possesses. This is how analyzers and sense organs are arranged.
Anterior chamber of the eye
The anterior chamber of the eye is the space between the iris and the cornea, filled with a viscous fluid. Behind the iris is a biconvex lens 10 mm in diameter - an elastic and transparent lens. It is attached to the ciliary muscle, which is located in the choroid. If the tension of the ligaments decreases, that is, the ciliary muscle relaxes, the lens becomes more convex due to its elasticity and elasticity, and vice versa, the lens thickens with increased tension of the ligaments.
The posterior chamber of the eye is filled with fluid and is located between the lens and the iris. Behind the lens, the cavity of the eyeball is filled with a transparent gelatinous mass, the so-called vitreous body, which is designed to maintain the shape of the eyeball, give it elasticity and, in addition, keep the retina in contact with the sclera and choroid. This is the basic principle of the sensory organs and analyzers.
Retina
The retina, or mesh inner shell, is the most complex in structure. She lines the wall of the eyeball from the inside. It is formed by the nerve endings of the optic nerve, receptor (photosensitive) cells (cones and rods) and pigment cells, which are located in the outer layer of the retina. A black spot is visible pigment layer through the opening of the pupil. This is how sensory organs and analyzers work.
The eye is considered an optical apparatus. Its light-refracting system includes: the vitreous, the crystalline lens, the aqueous fluid of the anterior and posterior chambers, and the cornea. Each element of the optical system transmits light rays through itself, refracting, reaching the retina and forming an inverted and reduced image of objects visible to the eye.
With what analyzers the sensory organs are connected, it has now become clear.
Light perception mechanism
The retina contains about 130 million rods and 7 million cones. In the cones, iodopsin pigment is present, which allows you to perceive colors in daylight. They can also be divided into three types with spectral sensitivity to blue, red and green.
In rods and cones (photosensitive receptors) when exposed to light rays, complex photochemical reactions occur, which are accompanied by the splitting of visual pigments into compounds. This photochemical reaction contributes to the occurrence of excitation, which is transmitted through the optic nerve in the form of an impulse to the intermediate and midbrain (subcortical centers), and then to the occipital lobe of the cerebral cortex and is modified into a visual sensation. Visual purple is restored in the dark.
What is the difference between the analyzer and the sense organ? About it below.
Visual hygiene
Factors contributing to the preservation of vision:
- the light source is located on the left;
- the workplace should be well lit;
- the distance from the eye to the subject should be approximately 30-35 centimeters.
Reading in vehicles (as the ever-changing distance between the lens and the book leads to a weakening of the elasticity of the ciliary muscle and lens) or lying down also leads to visual impairment. You should protect your eyes from getting into them very bright light, dust and other particles. There are no less important sensory organs and analyzers. Biology test everyone can pass.
Organ of hearing
The middle ear, outer ear and part of the inner ear belong to the auditory organ.
The auricle and the external auditory meatus, ending in the eardrum, enter the outer ear. The shape of the auricle resembles a funnel consisting of fibrous tissue, which is covered with skin, and cartilage. The length of the external canal of the auditory canal is 2-5 cm. Viscous sulfuric fluid, which traps microorganisms and dust, is secreted by special canal glands. Elastic and thin in 0.1 mm tympanic membrane helps to transmit sound vibrations into the middle ear.
The middle ear is located behind the eardrum in the temporal bone of the skull. Its tympanic cavity has a volume of approximately 1 cm 3 and contains three auditory ossicles: a stapes, an anvil and a malleus. Through the Eustachian (auditory) tube, the tympanic cavity is connected to the nasopharynx. The pressure on both sides of the tympanic membrane is evened out thanks to the auditory tube, it also maintains integrity.
The very small auditory ossicles form a movable chain with each other. The malleus (the outermost bone) is connected to the eardrum, and its head with the anvil - with the help of a joint. The anvil, in turn, is attached to the stepladder, and it is attached to the wall of the inner ear. The auditory ossicles perform the function of amplifying 20 times and transmitting the sound wave to the inner ear from the eardrum.
The inner wall of the tympanic cavity, which separates the middle from the inner ear, has two small windows (holes) - oval and round, which are tightened by a membrane membrane. The stapes rests against the membrane of the oval opening.
Many are interested in sense organs and analyzers. A biology test, for example, contains questions on this topic.
The inner ear is located in the temporal bone, is a system of channels and cavities, which is called the labyrinth. Together they form a bone labyrinth, and inside it is a membranous labyrinth. Between the membranous and the bony labyrinth, the space is filled with a fluid called perilymph.
The membranous labyrinth inside is filled with a fluid called endolymph. Three sections stand out in the inner ear: the cochlea, the semicircular canals and the vestibule. Only the cochlea can be attributed to the auditory organ - the bone canal twisted spirally in 2.5 turns. The cavity of this channel is divided into three parts by two membranes.
One membrane, the main membrane, consists of connective tissue, including approximately 24 thousand thin fibers of different lengths and located across the cochlea. The longest fibers are at the apex of the cochlea, and the shortest are at its base. On these fibers, there are 5 rows of sound-sensitive hair cells with a covering membrane growing above them. Together, these elements form a cortic organ, that is, the receptor apparatus of the auditory analyzer.
The difference between the analyzer and the sense organ is that the analyzer perceives information from the sense organ, which receives it from the outside world.
Sound perception mechanism
The fluids of the cochlear canals take vibrations of the stapes, which abuts against the oval window membrane. This leads to vibrations of the fibers of the main membrane resonant. Including a high tone of sounds causes vibrations of short fibrils, which are located at the base of the cochlea, and low tone causes vibrations of long fibrils located on top. At the same time, the hair cells touch the covering membrane, changing its shape.
Hair cells, touching the covering membrane, change shape. This leads to the appearance of excitement transmitted to the midbrain in the form of impulses along the fibers of the auditory nerve and then to the hearing zone of the cortex of the temporal lobe, where the excitation passes into the auditory sensation. The human ear can perceive the frequency range of sounds of 20-20000 Hertz.
Hearing hygiene
To preserve hearing, it is necessary to prevent mechanical damage to the eardrum. The ear canal and auricles must be kept clean. If excess sulfur accumulates in your ears, you should consult a specialist. Strong and prolonged noises have a detrimental effect on the organ of hearing. It is very important to treat colds in a timely manner, since pathogenic bacteria can penetrate the tympanic cavity through the Eustachian tube and provoke inflammation. We examined analyzers and human senses.
Other analyzers
There are also tactile, gustatory and olfactory analyzers. Touch is called irritation of several skin receptors. Taste buds make up the peripheral part of the taste analyzer (tongue, oral mucosa). Its higher centers are located in the departments of the brain. The olfactory analyzer receives information from receptors located in the nasal mucosa. The sense of smell in humans is most poorly developed, unlike animals.
The work of the vestibular apparatus is interesting, it regulates the position and orientation of the body in space. Age and gender affect the performance of analyzers. For example, women have a better developed sense of smell and perception of shades of color. In men, taste buds work better.
The meaning of sensory organs and analyzers
These organs are extremely important for humans. Without them, survival would be difficult. Who has a poorly developed sensory organ or analyzer, features in the development and perception of the world are observed. They are poorly oriented in space. Motor function impaired.