AAP Special Senses Flashcards
1
Q
What is hearing?
A
- process that converts vibrations of air molecules into nerve impulses
- these are interpreted by the brain
2
Q
What are the three parts of the ears?
A
- external ear
- middle ear
- inner ears
3
Q
Describe the external ear.
A
- The outer portion, called the Pinna, contains mainly elastic cartilage and skin
- the external auditory canal, carry the sound wave to the tympanic membrane (ear drum)
- the ear drum is a paper-thin membrane; vibrates when the sound wave strikes it
4
Q
Describe the middle ear.
A
- the cavity behind the ear drum
- Filled with 3 small tiny bones known as ossicles (malleus, incus, stapes)
- The ossicles link the ear drum to the cochlea of the inner ear (snail-shell structure)
- the end of stapes is attached to the membrane of oval window of the cochlea
- the auditory tube (Eustachian tube) connects the middle ear cavity to the pharynx, which balances air pressure on the two sides of the eardrum
5
Q
Describe the inner ear.
A
- the structure for hearing is a shell-shaped structure known as the cochlea
- there are 2 membrane-covered openings on the cochlea known as the oval windows and round windows
- the receptor organ of hearing is called the organ of Corti (cluster of hearing cells and supporting cells) which connect to the cochlear nerve
- organ of corti runs along the whole length of cochlear
- The mbn covering the organ of corti is called the tectorial mbn
- there are hair cells sitting on the basilar membrane
- the cochlear duct is filled with fluid called endolymph
- the U-shaped outer tube (lies on either side of the cochlear duct) contains fluid called perilymph
- sound waves cause the vibration of the oval windows membrane, endo and perilymph and finally the hair cell to activate the cochlea nerves, which carry signals to the auditory cortex
6
Q
How are sounds detected in the body?
A
- sound waves are picked up by the pinna and transmitted down the ear canal to the tympanic mbn and auditory ossicles
- the vibrations of stapes push and pull the mbn on the oval window, which causes the vibrations of perilymph
- vibration of perilymph causes the movement of endolymph in cochlear duct
- this leads to the movement of hair cells and bending of hairs
- nerve impulses generated by movement of hair cells travel along the vestibulocochlear nerve to the auditory cortex, where they are interpreted as sound
- different frequencies of sound wave stimulate different areas along the length of the organ of Corti
7
Q
What is the organ that controls the balance of the body?
A
vestibule
8
Q
What is the vestibule?
A
- consists of 3 tiny, fluid-filled tubes (semicircular canals) in the inner ear
- when the head moves around, the liquid inside the semicircular canals moves the tiny hairs that line the canal
- this allows the hair cells to predict a loss of balance and sends signal to the brain via the vestibulocochlear nerve to adjust movement
9
Q
Describe taste buds.
A
- responsible for taste
- chemoreceptors consisting of sensory (gustatory) cells surrounded by supporting cells
- mainly found at the roof of the tongue
- chemicals enter the taste buds and come into contact with the hair-like structure of the sensory cell to activate the sensory cells
- activated sensory cells send the signals to the brain to create sense of taste
- the nerves carrying the information to the brain are cranial nerves IX (9) and VII (12)
10
Q
Describe the sense of smell.
A
- sense of smell known as olfaction and is achieved by the olfactory epithelium covering the nasal cavities
- the axon leaving each olfactory cell combine with other axons to form the olfactory nerve
- chemicals responsible for smell dissolves in the mucus of the nasal cavity and stimulate the epithelial mbn for the production of nerve impulses
- these are transmitted along the cranial nerve 1 to olfactory bulbs of the forebrain, where they are interpreted as smell
