A & P - Special Senses Flashcards
what are the purpose of the special senses?
to bring information about external environment to CNS
what is the main function of the eye?
to detect visible light in the form of colour
what is the conjunctiva of the eye?
lines inner surface of eyelid and covers outer surface of the eye
what keeps the conjunctiva moist and clean?
lacrimal glands continually produce tears
name the two filled cavities of the eyeball, what are they separated by?
anterior
posterior
separated by lens
name the three layers of the eyeball wall, inner to outer
neural
vascular
fibrous
in what layer of the eye are the sclera and cornea?
fibrous tunic
what are the sclera and the cornea and where in the eye are they located?
sclera - white of eye, around the side of eye
cornea - transparent layer that covers iris and pupil
what is the function of the sclera and cornea?
protection of eye and attachment for muscles
what does the vascular tunic of the eye consist of?
iris
cilliary body
choriod
what is the function of the iris?
pigmented area containing smooth muscle fibres that contracted to change diameter of pupil
what is the function of the cilliary body?
thickened area containing suspensory ligaments that hold lens
what is the function of the choroid?
contains capillary network
what is contained in the neural tunic or retina?
photoreceptors - rods & cones
what is the function of the rods and cones?
rods - work in dim light, many
cones - require more light, provide colour vision, fewer
what is used to view the retina?
opthalmoscope
what is the fovea centralis?
only cones
focused light
used for looking directly at an object
what is the optic disc?
where optic nerve leaves the eye and blood vessels enter/leave.
no photoreceptors
blind spot
what is diabetic retinopathy?
over accumulation of glucose leads to damage of retinal vessels. leads to oedema and swelling of the macula - blurred vision
what is the posterior cavity filled with and why?
vitreous humour (jelly-like) maintains pressure within eye keeps space for eyeball
what does the anterior cavity consist of?
anterior and posterior chambers - separated by iris
what does the anterior cavity contain?
aqueous humour - replaced every 90 mins
what is glaucoma?
form of blindness - due to increased intraocular pressure caused by build up of aqueous humour - in turn putting pressure on retina and optic nerve
where in the eye is light focused?
retina
cornea
lens
humours
how are action potentials transmitted from the eye to the brain?
light strikes retina
action potential transmitted along optic nerve to occipital cortex in brain
where do the two optic nerves connect?
optic chiasma
where do axons from the optic chiasm pass to?
visual cortex in occipital lobe
what is another function of the ear besides hearing?
balance
name the three parts of the ear
external
middle
inner
name the three areas of the external ear
auricle
tympanic membrane
external acoustic (auditory) meatus
what is the function of the auricle?
supported by cartilage
collects sound waves
what is the function of the tympanic membrane?
separates external and middle ear
sound waves cause eardrum to vibrate
what is the function of the external acoustic (auditory) meatus?
passageway extending through temporal bone to eardrum
glands produce cerumen (wax)
hairs in canal and wax trap foreign objects, protecting tympanic membrane
what separates the middle and inner ear?
oval and round windows
name the 3 auditory ossicles in the middle ear
malleus
incus
stapes
what is the function of the auditory ossicles?
to transmit vibrations from tympanic membrane to oval window
how many times larger is the tympanic membrane than the oval window, what effect does this have?
20 times
force of vibration is increased by x20
what connects the middle ear to the nasopharynx?
Eustachian tube (auditory tube)
what is otitis media?
middle ear infection
infection spreads from nasopharynx up the auditory tube, if sever pus build up can rupture tympanic membrane
what does the inner ear consist of?
series of interconnecting bony, fluid filled channels in temporal bone
what is the cochlear concerned with?
hearing
what are the vestibular and semi-circular canals concerned with?
balance
what transmits impulses from the inner ear to the brain?
vestibulocochlear nerve (CN VIII)
how is sound transmited through the ear?
sound waves collect in auricle
sound waves hit tympanic membrane
vibration transmitted and amplified through ossicles
vibration of stapes on oval window causes fluid in cochlea to vibrate
vibrations stimulate spiral organ triggering AP
where does the information from the cochlea go?
primary auditory cortex in temporal lobe
name two types of hearing impairment
conductive
sensorineural
what is a conductive hearing impairment?
deficiency in transmitting sound waves form outer to inner ear
what is a sensorineural hearing impairment?
involves spinal organ, neural pathway or primary auditory pathway
which parts of the ear are concerned with balance?
vestibule - static equilibrium
semi-circular canals - kinetic equilibrium
what does the vestibule consist of?
utricle
saccule
how are action potential transmitted from the vestibule and the semi-circular canals?
via vestibulocochlar nerve to brainstem
what causes motion sickness?
continual stimulation of semi circular canals
what is the sense of smell?
response to airbourne molecules (odorants)
what does the olfactory system consist of?
olfactory epithelium
olfactory nerve (CNI)
olfactory bulb and tract
describe the process of smelling
- odorant enter nasal cavity
- presented to receptor protein on olfactory epithelium
- olfactory nerve stimulated
- info transmitted to olfactory cortex
what is anosmia?
inability to smell - can be congenital or acquired
where are taste buds located?
tongue
soft palette
pharynx
epiglottis
how many taste cells does each bud contain?
40
describe a taste cell
each has ting hair-like projections.
sensory receptors of taste hair
list the 5 tastes
sweet sour salty bitter umani
name the areas of the tongue which are most sensitive to certain tastes.
front - sweet
sides - sour
back - bitter
describe the process of tasting
- tastants bind to receptors on taste hairs
- action potential initiated in sensory neuron
- sensory axons (facial, glossopharyngeal, vagus nerves)transmit AP
- info transmitted to taste cortex in partial lobe
name three types of taste loss
ageusia - total loss
hypogeusia - partial loss
dysgeusia - distortion or alteration of taste
what can cause taste loss?
neurological damage
side effects of drugs
endocrine disorder
radiation therapy
