The ear is a very important organ that is of great importance in the life of any animal and person. The structure of the ear is closely related to its functions. This is not only a hearing aid, but also an organ of balance, which helps to navigate in space. In humans, the normal functioning of the organ of hearing is also responsible for the development of speech.
The evolution and structure of the organ of hearing in animals . Before considering the structural features of the human ear, it makes sense to get acquainted with the various forms of this organ in animals. The hearing aid is designed to perceive sound waves, which is important both in communication between individuals and for survival.
In arthropods, hearing organs are represented by specialized sensilla, which are located on the setae, antennae, or body.
The structure of the fish ear is still quite simple, since the hearing organ has only the inside. It is a complex of three semicircular canals, each of which is located in a mutually perpendicular area. Special chambers contain otoliths, which begin to oscillate when a sound wave passes. It is this oscillation that creates an impulse that is transmitted through the nerve to a certain area of the brain, where this information is processed.
In amphibians, the middle part of the ear appears, which is covered with a tympanic membrane. There is also one auditory ossicle - stapes. The inner ear is separated from the middle by an oval window. The cavity of the organ of hearing connects with the oropharynx - this helps to equalize the pressure.
Of course, the structure of the ear in mammals is considered the most complex. Representatives of this class, as a rule, have already formed all three departments of the organ of hearing, have an auricle, auditory ossicles, an otolith apparatus and a fully formed vestibular system.
The structure of the human ear . The human ear consists of three parts - external, middle and internal.
The outer ear is represented by the auricle and the external auditory canal. The auricle is a large, elastic cartilage covered in skin. Its main function is to capture sounds. The auricle passes into the ear canal, which is lined with skin from the inside. It ends blindly on the eardrum.
The middle ear begins with the eardrum, which transmits sound vibrations to the auditory ossicles - the malleus, the anvil and the stapes (by the way, these are the smallest bones of the human body). The sound wave causes vibration of the bones, which is transmitted through the oval window into the cavity of the inner ear. The drum cavity is connected by the nasopharynx with the help of Eustachian tubes - thus, the pressure is equalized. It is interesting that if the sound is too intense or the pressure of the environment is too high, the ears are “laying”. In this case, yawning is reflexively caused - an open oral cavity reduces the likelihood of damage to the eardrum.
The structure of the inner ear is perhaps the most complex. It consists of a bone labyrinth in which a vestibule, a cochlea and three semicircular canals are distinguished. The cochlea is the most important part of the organ of hearing, since it is she who perceives sound vibrations and turns them into a nerve impulse.
A webbed labyrinth filled with a special liquid is located inside the cochlea. On its walls are specific receptors, which are represented by hair cells. Each such cell perceives lymph oscillations inside the labyrinth and transforms it into an electrical signal, which is then transmitted through the auditory nerve to the centers of the brain.
The three semicircular canals of the inner ear are the vestibular analyzer, which is responsible for spatial orientation, movement, and perception of body position.
You can notice that the structure of the human ear is quite complex, since this organ is responsible for the many functions of the human body. It is also interesting that children with congenital pathologies of the hearing aid cannot communicate normally, despite the fact that the entire speech system (language, pharynx, vocal cords) is functioning normally.