The senses

   1. Sensing function

   Living beings receive information through the senses and according to it, they produced a response. Thus they relate with the outside.

   In the picture, we see that when we touch a tentacle of the snail, it responses shrinking.

   The man has five senses: sight, hearing, taste, smell and touch. Each sense receives the direct action of the external environment. This information is transmitted through a nerve to the brain, where the response originates.

    2. The sight
The sense of sight lets us know the color, shape, position and distance of the bodies. The main parts of the eye are:
   - The eyebrow that prevent sweat drop on the eyes.
   - The eyelash that prevents dust enters in the eye.
   - The eyelids that close quickly to any hit or brush in the eye.
   - The cornea is a transparent membrane in contact with the outside.
   - The iris is the colored part of the eye.
   - The pupil is in the center of the iris.
   - The lens is a biconvex structure that focuses images.
   - The retina is a light-sensitive membrane which is on the back of the eyeball. The optic nerve comes from it and gives information to the brain.
   When much light comes, the pupil becomes smaller. When little light comes, the pupil dilates or enlarges.
   According to the distance of the object, the lens can flatten or make convex in order to focus well and see the picture clear.
   See the picture and note the similarity between the eye and a camera.

   3. Answers with the appropriate part of the eye : eyebrows, eyelashes, eyelids, cornea, iris, pupil, lens or retina

They prevent the entry of dust

It prevents sweat drop

They close to any hit in the eye

It is in contact with the outside

It gives color to the eyes

It is located in the center of the iris

Light -sensitive membrane

Transparent membrane

It is a biconvex structure

    4. The hearing

   The ear has two missions: it collects the external sounds and maintains the equilibrium. Its parts are:

   In the outer ear are:

   - The pinna.

   - The external ear canal that accumulates earwax and there are little hairs that prevent the entry of insects and dust.

   - The eardrum, which is a membrane similar to that of a drum. It collects the vibration caused by sound waves.

   In the middle ear, we have:

   - Four smallest bones called the malleus, incus, lenticular and stapes. They transmit vibrations.

   In the inner ear:

   - The cochlea, with cells that perceive sound.

   - The eighth cranial nerve that transmits information to the brain.

   - The labyrinth consists of semicircular canals that control equilibrium.

   5. Answers with the following parts of the ear: pinna, external ear canal, eardrum, smallest bones, cochlea, eighth cranial nerve or labyrinth

It is the ear

They transmit vibrations

It perceives vibrations

It perceives sound

It transmits information to the brain

It controls the equilibrium

    6. The smell

    The organ of smell allows us to perceive odors. The nose is the organ of smell.

   We distinguish these parts:

   - The nasal cavities are on the inside part of the nose.

   - The olfactory epithelium or pituitary, which perceives odors.

   - The olfactory nerve that transmits information to the brain.

   7. Answer with the following parts of smell: nasal cavities, olfactory epithelium and olfactory nerve

Inside part of the nose

Called pituitary

It transmits the information to the brain

It perceives odors

    8. The taste

   The tongue is the organ of taste.

   The sensory cells of tasted buds perceive flavors and transmit this information to the brain via the gustatory nerve.

   Tasted buds detect four tastes: sweet and salty at the tip of the tongue; the acid in the sides; and the bitter at the bottom.

   The flavor that we perceive in the brain is a mixture of the above.

    9. The touch

   This sense allows us to appreciate the shape, roughness and temperature of the bodies. We distinguish:

   - The epidermis is the most superficial part of the skin.

   - The dermis is the inner part of the skin, where the nerve endings or tactile corpuscles are. They receive and transmit sensations to the brain.

    10. Hygiene of the senses

   We should follow these instructions:

   - Do not touch the eyes with dirty hands.

   - Go to the optician when we observe any vision problem.

   - Keep the external ear canal clean. If a wax of earwax appears, it should be cleaned with tepid water or we should go to the doctor.

   - Avoid prolonged and intense noise because they can cause hearing loss and even deafness.

   - Keep the nose clean and do not introduce strange bodies.

   - Avoid very cold or very hot foods and drinks.

   - Wash hands and take a shower frequently.

   11. Answer if these advices are correct or incorrect:

Never go to the optician

Do not touch the eyes with dirty hands

Listen music with high volume

Drink hot drinks

Take a shower frequently

Clean the ear

Keep the nose clean

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®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) No 141, of 29-IX-1999
Plaza Playa de Aro, 3, 1º DO 44002-TERUEL