Sense Organs Flashcards
Which parts of the ear make up the outer ear
Pinna and auditory canal
What is the function of the pinna
Directs sound waves to the auditory canal
What is the function of the auditory canal
Transmits sound from pinna to the tympanic membrane
What are the parts of the middle ear
Tympanic membrane
Ear ossicles
Oval window
Round window
Eustachian tube
What is the tympanic membrane and what is its function
Tympanic membrane: a thin membrane that covers the opening between the auditory canal and the middle ear
Function:convert sound waves to vibrations that are transmitted to ear ossicles
What do the ear ossicles consist of and what are their function
Consists of anvil, hammer and stirrup
Function: transmit vibration in middle ear to oval window
Magnify the vibration (to accommodate for the fluid in the inner ear because sound in fluid becomes muffled/less clear)
What is the oval window and what is its function
Oval window: a thin membrane connecting middle ear to inner ear
Function: transmits vibration to inner ear
What is the Eustachian tube and what is its function
Eustachian tube: tube connecting the middle ear to the throat
Function: allows pressure in the middle ear to be equal to the atmospheric pressure so that pressure is the same on both sides of the tympanic membrane
What is the structure of the inner ear
Consists of bony labyrinth and membranous labyrinth
Bony labyrinth is system of canals and cavities in the skull
Bony labyrinth filled with perilymph
Membranous labyrinth is a system of membranous tubes and sacs found floating in the perilymph
Membranous labyrinth has the same shape as the bony labyrinth
Membranous labyrinth filled with endolymph
Bony labyrinth and membranous labyrinth filled divided in two sections: 1. Vestibular apparatus - for balance
2. Cochlea - for hearing
What is the vestibular apparatus comprised of and what is each part responsible for
Three semi-circular canals - direction and speed
Utriculus - have maculae which detect gravity
Sacculus - have maculae which detect gravity
What is the role of the utriculus and sacculus
Utriculus and sacculus contain maculae
Each macula has sensory cells with fine hairs embedded in a layer of jelly
Small crystals of calcium carbonate on the jelly called otoliths
Depending on position of head the weight of the otoliths will pull on different hairs
Interpreted by brain to tell us if we’re upright or not
What is the structure of the semi-circular canals
Three semi-circular canals positions at right angles to each other
Ampulla at base of each semi-circular canal
Ampullae contain sensory crista
What the function of the semi-circular canals
Responsible for detecting movement in head (direction and speed)
Endolymph fluid fills semi-circular canals and stimulates sensory crista as head moves
Fluid will flow in one of the semi-circular canals more than the others depending on the direction of movement of the head
This information is fed to the cerebellum help maintain balance
What is the cochlea
A Long, coiled, structure which is divided along its length into three compartments
What is the structure of the cochlea
3 compartments
Upper compartment: has perilymph and connects to oval window
Middle compartment: has endolymph and organ of corti
Lower compartment: has perilymph and connected to round window
Organ of corti has many sensory hairs which connected to the auditory nerve
How does the cochlea work
Vibration is transmitted from the stapes to the oval window then into the endolymph
Vibrations tug at the hair cells of the organ of corti
Sensory hair cells send impulse to the auditory nerve to the cerebrum (temporal lobe) which interprets the sound
Vibrations continue through perilymph of the lower chamber to the round window where they are lost to the air of the middle ear
What’s the function of the round window
Releases inner ear pressure and basilar membrane vibration
What is the difference between conductive deafness and neural deafness
When one of the mechanisms conducting the sound waves/vibrations fails e.g: tympanic membrane damaged
Neural deafness: problems of the inner ear (organ of corti) or the auditory nerve or temporal lobe of brain
What are the possible causes of deafness
Accumulation of wax against tympanic membrane
Long term exposure to loud noise
Hereditary
Infections e.g: meningitis
What are possible treatments of deafness
Hearing aids
Cochlear transplants