Introduction to Psychology

Introduction to Psychology of 97 The Ear Structure and Function- The transduction system of the ear is made up of tiny bones, membranes, and liquid-filled tubes designed to translate pressure waves into nerve impulses. At a speed of about 75 mph, sound waves travel into an auditory canal leading to the eardrum, a membrane that vibrates in response to sound waves. Beyond the eardrum is the middle ear, a cavity housing three tiny bones. The vibrating activity of these bones - the hammer (malleus), anvil (incus), and the stirrup (stapes) - amplifies the sound waves more than 30 times. The oval window forms the boundary between the middle ear and the inner ear. The inner ear contains the cochlea, a coiled snail- shaped tube that is filled with fluid and contains the basilar membrane, a sheet of tissue that runs its length. Resting on the basilar membrane is the organ of Corti, which contains about 16,000 tiny hair cells that are the actual sound receptors. The tips of the hair cells are attached to another membrane, the tectorial membrane. When sound waves strike the eardrum, pressure created at the oval window by the hammer, anvil, and stirrup of the middle ear sets the fluid inside the cochlea into motion. The fluid waves that result vibrate the basilar membrane and the tectorial membrane, causing bending of the hair cells in the organ of Corti. This bending of the hair cells triggers the release of neurotransmitters into the synaptic space between the hair cells and the neurons of the auditory nerve, resulting in nerve impulses being sent to the brain. 3.5 Taste Gustation is the sense of taste which is a chemical sense. Our sense of taste responds to only four qualities: sweet, sour, salty, and bitter. Every other taste experiment combines these qualities and those of other senses, such as smell, temperature, and touch. Taste buds are chemical receptors concentrated along the tip, edges, and back surface of the tongue. An additional taste sensation, called umami, increases the intensity of other taste qualities. 3.6 Smell Olfaction is the sense of smell. The receptors for smell are long cells that project through the lining of the upper part of the nasal cavity and into the mucous membrane. Olfactory receptors fire, sending their input to the olfactory bulb, a forebrain structure immediately above the nasal cavity. Each odorous chemical excites only a limited portion of the olfactory bulb, and odors are apparently related perceptions, statements or coded in terms of the specific area of the olfactory bulb that is excited. © 2015 Achieve Page 29