Five Sense Organs - Definition Of Five Sense Organs

By Author: Peter
Total Articles: 11
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The Eye
The eyes are the two organs of sight. They are located in the front upper part of the skull and consist of structures that focus an image onto the retina at the back of the eye which is a network of nerves that convert this image into electrical impulses to be recorded in a region of the brain. The eyeball lies in pads of fat within the orbit, a bony socket that provides protection from injury. Each eyeball is moved by six delicate muscles which are activated and coordinated by nerves in the brain stem. The eyeball has a tough, outer coat called the "sclera," or white part of the eye. The front, circular part is the "cornea" and is transparent. The cornea is the main lens of the eye and performs most of the focusing. Behind the cornea is a shallow chamber full of watery fluid, at the back of which is the "iris" (colored part) with the "pupil" (center). The pupil is black and its diameter is changed by light intensity to control the amount of light which enters the eye. Immediately behind the iris, and in contact with it is the crystalline lens, which contracts to alter its shape and allow focusing power.

The ...
... Ear
The ear is an organ for hearing and balance. It consists of three parts: the outer ear, the middle ear, and the inner ear. The outer and middle ear mostly collect and transmit sound. The inner ear analyzes sound waves and contains an apparatus that maintains the body's balance. The outer ear is the part which is visible and is made of folds of skin and cartilage. It leads into the ear canal, which is about one inch long in adults and is closed at the inner end by the eardrum. The eardrum is a thin, fibrous, circular membrane covered with a thin layer of skin. It vibrates in response to changes in the air pressure that constitute sound. The eardrum separates the outer ear from the middle ear. The middle ear is a small cavity which conducts sound to the inner ear by means of three tiny, linked, movable bones called "ossicles." These are the smallest bones in the human body and are named for their shape. The hammer (malleus) joins the inside of the eardrum. The anvil (incus) has a broad joint with the hammer and a very delicate joint to the stirrup (stapes). The base of the stirrup fills the oval window which leads to the inner ear. The inner ear is a very delicate series of structures deep within the bones of the skull. It consists of a maze of winding passages, called the "labyrinth". The front (see cochlea) is a tube resembling a snail's shell and is concerned with hearing. The rear part is concerned with balance.

Nose
Smell is often considered to be the least important of all the senses, but it may be one of the oldest, and probably acts on the subconscious more than the other senses. A further sign of the importance of the sense of smell is the way it becomes a major source of information when other senses are not working, especially sight. Only a small part of the nose and nasal cavity is taken up by the organs of smell; the rest of it is mainly concerned with processing the airflow on its way through to the lungs. The walls of the nasal cavity, and particularly the flaplike middle and inferior conchae, are coated with respiratory mucous membranes which incorporate a vast number of tiny hairlike cells which act to move waves of mucus toward the throat

Tongue
Anchored to the floor of the mouth and slung at the rear from muscles attached to a spiky outgrowth at the base of the skull, the tongue is a strong muscle that is covered by the lingual membrane, which has special areas which detect the flavor of food. The tongue is made up of muscles covered by mucous membranes. These muscles are attached to the lower jaw and to the hyoid bone (a small, U-shaped bone, which lies deep in the muscles at the back of the tongue) above the larynx. There are very small nodules, called papillae, from the top surface of the tongue, which give it its rough texture. Between the papillae at the sides and base of the tongue are small, bulblike structures that are sensory organs, called "taste buds," which enable us to enjoy the sensations of flavor and warn us when food is unfit to eat.

Skin
Skin is the outside covering of body tissue, which protects inner cells and organs from the outside environment. The skin is the largest organ of the body, and its cells are continuously replaced as they are lost to normal wear and tear. The skin totals between twelve and twenty square feet in area and accounts for 12% of body weight.

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