Light goes into your eye through an opening called the pupil. The retina is a light-sensitive layer at the very back of the eye. It uses special cells called rods and cones to process light. Cells there turn light into electrical signals. Cones sense color and need more light than rods. Rods work better in dim light. Two eyes help you judge depth, how far away things are.

Sound waves go into your ears and make your eardrums vibrate. The cochlea is a snail-shaped part of the inner ear. It turns vibrations into nerve signals. You may have heard that you only have five senses. In fact, you also have a sense of balance. Your inner ear has semicircular canals. They tell your brain when your head turns.

Your nose lets you smell. Smell helps you taste. You use your tongue to taste. People are born with about 10,000 taste buds. The small bumps on your tongue, called papillae, hold your taste buds. Taste buds can detect sweet, sour, bitter, salty and umami (savory) flavors. Food has to dissolve in saliva before you can taste it.

Your skin has nerve endings. They let you feel hot, cold and touch. Fingers and lips have more touch receptors than your back, so they feel more. Braille is a way of reading with the fingers, using raised dots. American Sign Language is the primary language of many North Americans who are deaf or hard of hearing. It is expressed by movements of the hands and face.

Your senses send messages to your brain. Smell receptors in the nose send messages to the brain. The brain identifies the smell. The auditory nerve carries messages from the ear to the brain. You may think your eyes alone make the picture you see. In fact, the optic nerve carries messages from the eye to the brain.

Words to know

• retina: back of eye
• cochlea: snail-shaped ear part
• saliva: spit
• semicircular: half-round
• papillae: tongue bumps

The short version

Your senses send messages to your brain. Special cells in the retina turn light into electrical signals. The cochlea turns vibrations into nerve signals. Smell receptors in the nose send messages to the brain, which identifies the smell. The semicircular canals in your inner ear help you stay balanced.

Quick facts

• Cones sense color and need more light than rods, while rods work better in dim light.
• Food has to dissolve in saliva before you can taste it.
• Taste buds can detect sweet, sour, bitter, salty and umami (savory) flavors.
• Fingers and lips have more touch receptors than your back, so they feel more.