neurosensory Mr. Schmidt
Summit Career College

The ear is divided into 3 parts: the outer ear, the middle ear, and the inner ear. Each section performs its own separate function in a process that converts sound waves into nerve impulses, which are then transmitted to the brain. The outer ear has two parts; the pinna and the external auditory canal. The outer ear collects and channels sound. The middle ear, or tympanaic cavity, is a small cavity hollowed out of the temporal bone. It is an intermediary in the processing of sound energy. It is responsible for increasing the intensity of incoming sound waves and transforming them into mechanical vibrations that can easily travel through the inner ear. The inner ear has 2 parts: one is made of bone, and the other of a membrane that lies inside the bone. Both have complicated shapes, and for this reason they are called labyrinths. Each labyrinth has 3 parts: vestibule, semicircular canals, and cochlea. The inner ear contains the receptor cells, which receive the mechanical vibrations and transmit them to the brain.

The eyeball lies nestled in fat within two bony sockets called the orbital cavities of the skull where it is situated above and lateral to the center. Of all the senses, eye sight is often considered the most important. According to one estimate, four-fifths of everything we know reaches the brain by electrical signals. The eyes receive information from light rays. The light rays are either absorbed or reflected. Objects that absorb all of the light rays appear black, whereas those that reflect all of the light rays appear white. Colored objects absorb certain parts of the light spectrum and reflect others. When you look at something the light rays reflected from the object enter the eye. The light is refracted by the cornea and passes through the watery aqueous humor and pupil to the lens. The iris controls the amount of light entering the eye. Then the lens focuses the light through the vitreous humor onto the retina, forming an image in reverse and up side down. Light sensitive cells in the retina transmit the image to the brain by electrical signals. The brain sees the image right side up.

Smell is the most basic and most primitive of the senses. It is some 10,000 times more acute than our sense of taste. In fact, most food flavors are smelled, not tasted, as anyone with a heavy cold will verify. Nasal congestion prevents the little eddies of air, stirred up by the action of chewing and swallowing from reaching the receptors in the roof of the nasal cavity. Human smell receptors distinguish several thousand different types of smell. Some people have a better sense of smell than others. The nose also plays an important role in conditioning the inspired air for the lower respiratory tract. This conditioning includes: the control of temperature, humidity and the elimination of dust and infectious organisms.
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