The Senses

Vision Photoreceptors perceive different wavelengths of light as different colors.

Parts of the eye Pupil- small opening that allows light into the eye Iris – colored portion of the eye that adjusts the size of the pupil Lens- transparent disc behind the iris that focuses light on the retina

Parts of the Eye Retina – inner surface of the eye that contains photoreceptors Rods – photoreceptors that are good at differentiating light and dark Cones- photoreceptors that respond to different colors- don’t work well in low light levels.

Parts of the Eye Optic Nerve – carries signals from the photoreceptors to the brain. Each eye has a blind spot that is caused by the lack of photoreceptors where the nerve leaves the eye. Cornea – Clear protective layer at the front of the eye.

Hearing Sensory receptors that respond to vibrations in the air around us.

Parts of the Ear Auditory canal – tube that leads to the eardrum. Eardrum- membrane that causes bones to vibrate in the ear when hit by sound waves.

Parts of the Ear Auditory Ossicles – Bones in the ear that conduct sound waves from the eardrum to the cochlea. Cochlea – portion of the ear that transfers mechanical waves into electrical nerve impulses.

Parts of Ear Semi-circular canals- section of the inner ear that senses the position of the head compared to gravity Helps keep balance. Eustachian Tube – tube that connects inner ear to throat. Keeps fluid from building up in the ear.

Taste and Smell Sensory receptors capable of differentiating between chemicals Smell – humans can differentiate between thousands of smells. Taste – without smell, humans can only taste four sensations – sweet, sour, bitter and salty.