The nervous system of birds, its features
The surrounding world is difficult to imagine harmonious without contemplating the flight of birds and the sound of their chirping. As noted by experts, the impact of birds on human life is more significant than one can imagine. Their role is not limited to aesthetics, for example, agriculture cannot do without these pest control aids. And do not forget that at one time they were also the instigators of bright engineering thought for the creation of aircraft. But that's not all. Today, medicine effectively uses the singing of birds for the treatment of the human nervous system. Ornitherapy was officially recognized as an effective method to cure nervous diseases, disorders and depressions.
Birds are amazing animals presented by nature. But what about their nervous system, how is it built, and what happens in their head?
General characteristics of the class
The class of birds is one of the largest groups among the vertebrates. Their existence on earth is estimated in millions of years.They are highly organized warm-blooded animals and are descended from primitive reptiles. The main feature of the birds, which appeared in the process of evolution, is the ability to fly when the front limbs transformed into wings. The surface of the body is covered with horn formations - feathers, which provide gliding through the air during the flight and provide thermal insulation.
The feathery group consists of more than 10,600 animal species and is distinguished by a great variety. Their general characteristics include: a lightweight skeleton, developed muscles, a four-chamber heart, air sacs (involved in breathing), a bladder, reproduction through the laying of eggs and an intense metabolism. A complex form of behavior and a high level of development of the nervous system of birds distinguishes them from reptiles. In addition, they have significantly better developed organs of vision and hearing.
Features of the nervous system of birds
In the nervous system of birds, the same sections are defined as in all vertebrates. It is less developed than in mammals, but there are features of a developed organization.Morphologically, this is explained by the fact that the bird's brain has a greater mass than the dorsal. In most units, only the forebrain constitutes 52-62% of the total mass of the brain, and in some it reaches 70%, for example, in parrots.
The nervous system in the class of birds is divided into central and peripheral. And it is worth noting that the peripheral is not much different from reptiles. The whole essence is in the organization of the central nervous system, which is represented by the brain and spinal cord, and the spinal nodes.
In terms of its functionality, the nervous system of birds is no different from fish, amphibians, reptiles and mammals. It faces the same tasks: uniting all body systems into a single whole, adjusting the work of the organs and ensuring communication with the external environment.
The proper level of brain development gives the birds the opportunity to develop certain forms of behavior and adapt to different situations. It is represented by the following organs: the big brain (two hemispheres), the midbrain, the cerebellum, and the medulla. At the same time, the great brain of birds, in contrast to reptiles, has much more developed hemispheres, which is a consequence of the growth and enlargement of striped bodies.It is highly developed and virtually covers all departments, with the exception of the cerebellum. For this reason, the midbrain is not visible from above; it is pushed aside more and more to the sides and downwards. In the cortex of the cerebral hemispheres, the furrow and gyrus are absent, in addition to the sylvian groove.
The cerebellum is quite large and well formed in all birds. Its top layer is completely composed of gray matter. It has a folded structure and contains a developed worm with longitudinal grooves and small lateral hemispheres. In front it closely borders the edges of the hemispheres of the large brain, and behind it covers a significant part of the medulla oblongata. Being connected to the entire central nervous system, the cerebellum is the center of control of movements and balance.
The function of the medulla oblongata is the role of a mediator of the passing impulses that emanate from the higher parts of the brain to the spinal cord and in the feedback. The medulla oblongata is somewhat thickened and has a relative curvature from the underside. This part of the brain differs from others in that its gray matter is spread out among white in the form of peculiar clusters - nuclei.Nervous centers that are most important for the life of birds are concentrated in specific nuclei: secretion of the digestive glands, cardiac activity and respiration, centers of regulation of metabolic processes and protective reactions. Their destruction leads the animal to instant death.
Also in the function of the medulla oblongata is involved in maintaining muscle tone. Regular impulses come from the inner ear to the medulla oblongata, and it, not without the participation of the midbrain, helps to maintain the required body position of the bird in space. The medulla oblongata, without any clear boundaries, flows in its upper part into the legs of the large brain, in the lower part into the dorsal.
The structure of the spinal cord of the nervous system of birds is in many ways similar to mammals. By sight, it resembles the shape of a white cord and runs along the entire length of the back ridge, breaking from the first cervical vertebra and ending with an elegant string in the sacral canal. There are two small seals - cervical and lumbosacral, providing the beginning of the nerves of the thoracic and pelvic limbs, respectively.
The spinal cord fulfills the duty of the main regulatoris a conductor of nerve signals to the upper branches of the central nervous system, and, accordingly, provides feedback. Virtually all motor nerves make their way out of the spinal cord. With his mediation, the muscles of the body and limbs are activated, vascular smooth muscles, muscle groups involved in defecation, and others are also stimulated.
Bird cranial nerves
The cranial nerve originates from the brain and passes through the opening of the skull. Birds, like reptiles and mammals, have 12 pairs of cranial nerves, but some of them are poorly developed. All nerves are specialized and mainly provide the organs of the head, with the exception of the vagus nerve.
- Olfactory nerve (1 pair) - determines the sensitivity to odors.
- Optic nerve (2 pairs).
- The oculomotor nerve (3 pairs) - motor.
- Block nerve (4 pairs) - motor.
- The trigeminal nerve (5 pair) - sensory and motor functions.
- The abducent nerve (6 pair) - motor.
- The facial nerve (7 pairs) - motor and sensory functions, in birds is poorly developed.
- The auditory nerve (8 pair) - the function of hearing and orientation in the external environment.
- Tongue and pharyngeal nerve (9 pairs).
- The vagus nerve (10 pairs) is sensory-motor, it belongs to one of the segments of the autonomic nervous system, one of the largest cranial nerves.
- The accessory nerve (11 pairs) - motor function, supplies nerves to the muscles of the neck and back.
- The hypoglossal nerve (12 pair) - control of the muscles of the tongue.
Vegetative nervous system
The entire nervous system of a bird is subdivided according to its functional characteristic into somatic (serving apparatus of movement) and vegetative, the nerve fibers of which carry impulses to the executive organs. And if the somatic nerves protrude only from parts of the spinal cord, the autonomic nerves come from different parts of the central nervous system. They move to all internal organs, but, having not reached the goal, they join in reaction with neurons, whose neurites approach a certain innervated organ. The resulting neuronal compound is a vegetative node - the ganglion.
The vegetative nervous system of birds regulates and adapts the state of the organs of the whole organism, adapting them to a single common activity and external environmental conditions.
Sensory organs and the nervous system of birds
The dominant role of the vital processes of each organism is assigned to the nervous system. It helps to connect the body with the external environment, when incoming stimuli are recorded by the senses. In birds, they represent a rather complex mechanism, comprising receptor, conductor and central divisions. The central division is located in the cerebral cortex, where incoming stimuli are perceived and carefully analyzed.
Receptors (nerve endings) represent the peripheral part of the sense organs and are located in all parts of the bird's body. The leading organs of perception include receptors of the retina and the inner part of the ear. They respond only to certain stimuli, light and sound, respectively. In terms of functionality, all receptors have divisions: tactile, phonoreceptors, photoreceptors, baroreceptors, and others. Also, the receptors differ in their external form and structure: rollers, cones, corks, spirals, plates and others. The most complex structure has the receptor parts of the eye and the auditory canal.
Manifestation of intelligence
The brain of birds is significantly inferior to the higher mammals in the development of the cerebral cortex. But studies have shown that its functional properties deserve attention. In solving various kinds of problems, the birds demonstrated such forms of behavior that were sometimes superior to mammals with more developed cerebral cortex. This allows us to draw conclusions: in birds, developed intelligence is determined.
When communicating with each other, birds use various sound signals in which they put meaning: danger, aggression, help, sympathy. They showed their clear mental abilities in comprehending the account, using methods of foraging, teaching the song to singing and human parrots. In short, the nervous system of birds, with a more complex organization of the brain, determines their behavior and the development of numerous instincts. And as a result of recent psychological studies of the brain of birds, it became known that some species of birds are inferior only to humans by intelligence.