12 03 07 - Sense Organs III

12 03 07 - Sense Organs III - Chapter 12: The sense organs...

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Chapter 12: The sense organs Hearing Mammals: Incus quadrate Malleus articular Stapes/columella from the second arch In mammals the point of articulation of the jaw moves forward, freeing up the quadrate and articular in the posterior jaw (from the 1 st arch) Need pressure of equal side for tympanic membrane to vibrate Tympanic membrane forms between inpocketing and pharynx Have a well developed external ear (pinna) that funnels sound to the tympanic membrane The middle ear transmits vibrations from tympanic membrane to the oval window - the middle ear is an air filled chamber, lined with mucous membranes. It is an extension of the pharynx, connected by the Eustachian (auditory) tube . The oval window vibrates the perilymph on the other side. - the perilymphatic duct surrounds the choclear duct (lagena) allowing vibrations to pass to the main organ of hearing, the organ of Corti. - Frequency will vibrate a particular part of Choclea, making a distinguished sound Two ears, one on either head to determine where sound is coming from In owls one ear is much lower than the other This allows the owl to determine whether the sound is directly beneath them Its because they live in more than one plane Photoreception: Vision Prior to evolution of craniates the eye evolved
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12 03 07 - Sense Organs III - Chapter 12: The sense organs...

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