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Unformatted text preview: type of signal that they receive
• Heat, cold = thermoreception, which is carried out by specialized nerve endings in the skin.
• Hearing, touch = mechanoreception
• Outer ear is shaped to catch and channel sound waves into the ear canal.
• Middle ear (eardrum, ear bones) transmit and amplify signals.
• Inner ear contains a long membrane (basilar membrane) with sensitive hair cells that respond to
certain frequencies of sound. Loud or prolonged noise can damage these cells permanently.
• Touch receptors in the skin response to varying pressures, producing the sensation of touch.
• Sight = photoreception
• Light enters the eye through the cornea and pupil.
• Lens focuses the light on the retina on the back of the eye.
• Retina contains rod and cone cells, which contain light-sensitive pigments. Light causes the
pigments to break, releasing energy, which sparks a nerve signal to the brain.
• The image on the back of the eye is fuzzy and upside-down. The brain interprets the signal and
makes meaning of it. Because the brain is capable of “filling in” information, the brain’s interpretation
is not always faithful to reality.
• Rod cells detect light of all wavelengths, and can be active in dim light.
• Cone cells respond to certain colors of light, and give us color vision.
• Taste, smell, and pain = chemoreception
• Chemicals in our food stimulate taste receptors on the tongue.
• Five types of taste receptors: salty, sweet, sour, bitter, and “umami”
• “Flavor” is a combination of taste and smell.
• Chemicals in the air dissolve in the mucous in the nose, stimulating olfactory receptors located
in a small area inside the nose.
• There may be over 1000 different olfactory receptor proteins in in the receptors cells.
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- Winter '09