12.3 mechanoreceptors and chemoreceptors

mechanoreceptors

in inner ear. convert sound waves into nerve impulses that the brain will eventually perceive as sound

outer ear 2 parts

pinna- outside flap captures sound waves and directs them into inner ear.

auditory canal

amplifies and directs sound waves to tympanic membrane. contains hairs and earwax for protection

middle ear (air filled) 5 parts

tympanum- vibrates when hit by sound waves.

ossicles

contains 3 bones malleus, incus, stapes that transmit vibrations from tympanum to the oval window.

Eustachian tube

connects middle ear to pharynx to control air pressure. keeps air pressure equal on both sides of tympanic membrane

round window

flexible membrane to relieve pressure in inner ear from tapping oval window

oval window

flexible membrane that picks up vibration for stapes and transmits fluid in cochlea

inner ear (fluid filled) 8 parts

cochlea- coil fluid filled tube transforms vibrations to nerve impulses.

organ of corti

has hair cells that pick up vibrations between tectorial and basilar membranes.

basilar membrane

hair cells attached to it. picks up vibrations in cochlear fluid causing hair cells to vibrate

tectorial membrane

stereo cilia attached to hair cells bend against membrane when basilar membrane flexes

auditory nerve

carries nerve impulse from ear to brain

semicircular canals

fluid filled loops contains mechanoreceptors to sense head and body rotation

utricle and saccule

gravitational equilibrium

sense of hearing part 1

sounds waves vibrate tympanic membrane. waves are amplified and passed from the tympanic membrane to ossicles. the stapes taps the oval window and creates fluid waves within the cochlea. fluid waves cause vibration of basilar membrane. movement of basilar membrane causes sterueicilia of the hair cells to bend against the tectorial membrane.

sense of hearing part 2

hair cells sense being of stereo cilia and generate action potential that will be carried along the auditory nerve to the brain. nerve impulse is sent to the thalamus and the temporal lobe. the brain can perceive frequency and the direction the sound came from

high frequencies

stimulate hair cells close to oval window

low frequencies

stimulate hair cells far from oval window

hearing loss

caused by damage to hair cells or outer or middle ear. results in birth defects ear infections. greater amplitude of sound waves= louder noise

balance 3 structures semicircular canal

ampulla- at base of each canal contains hair cells and stereocilia. when head moves fluid moves and stimulates hair cells. impulse is sent to brain through vestibular nerve

utricles and saccules

movement along vertical and horizontal planes. CaCO3 stones called otoliths rest on top of membrane. when the body is still the otoliths res on the otolithic memrbrane above hair cells. when the body tilts gravity pulls on otoliths and the membrane sags stimulating some hair cells to send an impulse to vestibular nerve

proprioreceptors

mechanoreceptors info;ved in coordination found in muscles, joints and tendons