Hearing touch mechanoreception outer ear is shaped to

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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 • Taste • 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. • 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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