Special senses Flashcards
perception
conscious awareness of a sensation
general senses
temp
pain
touch
pressure
vibrations
proprioception
special senses
smell/olfaction
taste/gustation
vision
hearing
balance/equilibrium
where does olfaction occur
in nasal cavity either side of nasal septum
inferior to cribriform plate of ethmoid bone
what do olfaction organs consist of
olfactory epithelium and olfactory glands
process of smell
- air swirls in nasal cavity
- reaches olfactory organs diffusion into mucus
- cilia attached to receptor extends into mucus and chemicals interact
- binding of odorant’s changes permeability of membrane causing AP
- info relayed to cns
olfactory pathways
bundle of axons penetrate cribriform plate of ethmoid bone to reach olfactory bulb. axons leaving here go along olfactory tract to cortex of cerebrum, hypothalamus and limbic system
gustatory receptors
on superior surface of tongue, adjacent to larynx and pharynx
what are taste buds
taste receptors and specialised epithelial cells
why are taste buds on the side
to protect from mechanical damage
3 types of papillae
filiform (no buds)
fungiform (5)
circumvallate (100)
primary taste sensations
sweet
salt
bitter
sour
umami
water
what are gustatory cells
sensory receptor I taste buds extending microvilli into surrounding fluids through taste pore
taste mechanisms
- dissolved chemicals contact taste hairs
- stimulates changes in potential = AP
- monitored by 3 cranial nerves (facial, vagus, glossopharyngeal)
vision structure
extrinsic eye muscles
lacrimal gland
cranial nerves
blood vessels
fat
vision mechanism
- light enter and refracted at cornea and lens
- absorbed at retina by photoreceptors (rods and cones)
- interacts with photopigments
- photopigment splits altering flow of electrical current
photopigments
rhodopsin
opsin
retinal
cones and rods
central vision (colour)
periphery (intensity)
visual pathways
- 2 optic nerves reach into diencephalon at the optic chiasm
- half nerve fibres from each eye cross to reach thalamus on opposite sides of brain
- nuclei here relays info to reflex centres on brain stem and visual. cortex
hearing receptors
in temporal bone of skull
mechanoreceptors (pressure)
anatomy of middle ear
air filled cavity
separated from ear canal by tympanic membrane
contains auditory ossicles
what are the 3 auditory ossicles
malleus
incus
stapes
inner ear receptor location
in membranous labyrinth containing 2 fluids (endolymph and perilymph)
inner ear structure
boney cochlear contains cochlear duct (between 2 perilymph chambers)
dense boney labyrinth walls
round and oval window locations
round = base of tympanic duct
oval = base of vestibular duct
organ of corti
where hair cells of cochlear duct are
just above basilar membrane
stereoccllia of hair cells in contact with tectonal membrane
process of hearing
- sound waves arrive
- vibrations in tympanic membrane
- move 3 tiny bones
- move oval window
- move fluid
- presses against hair cells
- AP generated
what monitors cochlear hair cells
sensory neurones in spiral ganglion
auditory pathways
axons enter medulla and synapse at cochlear nucleus
info brought together
inferior colliculus synapsing
synapse in thalamus
auditory cortex of temporal lobe
reaches awareness
where are balance sensations provided
by hair cells of vestibular apparatus, semi circular canals and otoliths
balance mechanics
semicircular canals and otoliths pick up info on rotational body movements
(contain fluid filled chambers )
causes movement in canals
fluid presses on cupula
hair cells move
AP
where are hair cells for balance located
in ampulla
cupula
gelentin fluid
utricle and saccule
u = horizontal linear acceleration
s = vertical
equilibrium pathways
sensory neurones monitor hair cells of otoliths and canals
afferent fibres form vestibular branch of vestibulocochlear nerve
roles of vestibular nuclei
integrate sensory info from each side of head
relay info to cerebellum
relay info to cerebral cortex
send motor commands along efferent fibres to brain stem
