SMELL

Nose: olfactory and respiratory organ, located between the eyes. The external nose, composed of bone and cartilage, is the most prominent feature of the face in humans. The internal nose is a hollow structure above the roof of the mouth, divided by the septum into two nasal cavities that extend from the nostrils to the pharynx.

TOUCH

Skin: the flexible tissue enclosing the body of vertebrate animals. The main job is to protect your internal (inside) organs from drying up and to prevent harmful bacteria from getting inside. The average person has a total of six pounds of skin. The main layers are the Epidermis: Outer layer of skin cells, hair, nails, and sweat glands and the Dermis: Inner layer of living tissue, containing nerves and blood vessels.

SIGHT

Eye: organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing. Other types of eye are the simple eye, found in many invertebrates and the compound eye, found in insects and many other arthropods. The eye perceives sunlight.

HEARING

Ear: organ of hearing and equilibrium. The human ear consists of outer, middle and inner parts. The outer ear is the visible portion; the middle ear, separated from the outer ear by the eardrum, contains three small bones or ossicles. Because of their shape, these bones are known as the hammer (malleus), anvil (incus) and stirrup (stapes). Air reaches the middle ear through the Eustachian tube, or auditory tube, which connects it to the throat. The inner ear or labyrinth, contains the cochlea, which houses the sound– analyzing cells of the ear, and the vestibule, which houses the organs of equilibrium.

TASTE

Tongue: muscular organ occupying the floor of the mouth in vertebrates. In some animals, such as lizards, anteaters and frogs, it serves a food-

gathering function. In humans, the tongue functions principally in chewing, swallowing and speaking. The human tongue is covered by a mucous membrane containing small projections called papillae, which give it a rough surface. The appearance of the tongue is often an indication of body health; a pinkish-red colour is normal. In certain feverish diseases, a yellowish coating forms.