chapter 17 Flashcards
what are the special senses?
olfaction
gustation
equilibrium
hearing
vision
when you taste or smell what are you actually interpreting?
chemicals
where are olfactory organs found
they provide smell and are found in the nasal cavity of both sides of the septum
how many receptors in the nose?
10 to 100 million
what is olfactory transduction?
binding of an odor molecule to an olfactory receptor protein
for olfaction, the action potential travels to the
primary olfaction area, after the AP is depolarized by cyclic AMP
gustation
taste; provides information about foods and liquids consumed
gustatory epithelial cells/taste receptors
found in taste buds which are found on papillae & distributed on the tongue & in pharynx/larynx
5 types of taste
sweet sour salty bitter umami
4 types of papillae
filliform, fungiform, vallate and foliate
taste buds are made of three types of epithelial cells
supporting cells, basal stem cells and gustatory receptor cells
which cranial nerves are involved with taste?
- facial nerve (VII) info from anterior of tongue
- glossopharyngeal nerve (ix) info from posterior of tongue
- vagus nerve (X) info from taste buds of epiglottis and throat
how long do gustatory epithelial cells survive before replacement?
about 10 days
salty and sour receptors are
chemically gated ion channels that stimulation produces cell depolarization
sweet bitter and umami receptors are
g coupled proteins
vision
enables us to use visible light (400 to 700 nm) to detect visual images
wavelength
distance between two consecutive peaks of an electromagnetic wave
what are accessory structures of the eye
eyelids, eyelashes, eyebrows, lacrimal apparatus, extrinsic eye muscles
palpaebrae
aka eyelids, keep the eyes lubricated and remove dust and debris from the eye
palpebral muscles
control eyelid movement
what separates the upper and lower eyelids?
palpebral fissure
tarsal glands
small sebaceous glands that are lipid rich and keep the eye from sticking together
tarsal plate
fold of CT that gives the eyelids form and house the tarsal glands
conjuctiva
thin, protective mucous that lines the eyelids and covers the sclera
conjunctivitis
inflammation of the conjunctiva due to dilation of blood vessels in conjunctival epithelium
lacrimal apparatus
produces distributes and drains tears
pathway of tears
lacrimal glands
lacrimal ducts
lacrimal puncta
lacrimal canaliculi
lacrimal sac
nasolacrimal ducts
each lacrimal gland produce about
one mL of tears per day
eye wall layers
- outer fibrous layer
- intermediate vascular layer
- deep inner layer (house photoreceptors)
anterior chamber of the eye houses
aqueous humor between cornea and iris
posterior chamber of the eye houses
aqueous humor between iris and lens
the large posterior cavity of the eye is filled with
a gel like susbtance called the vitreous humor
fibrous layer
- outermost layer of the eye
contains sclera, cornea and corneal limbus - supports and protect the eye
- attachment sight for extrinsic eye muscles
- focus structures
corneal limbus
border between cornea and sclera
vascular layer is made up of the … and its functions are
iris, ciliary body, choroid
- route for blood vessels and lymphatic supply to eye tissue
- regulates light that enters the eye
- secretes and reabsorbs aqueous humor
- controls lens shape
iris
pigmented, flat ring structure
contains papillary muscles that change the diameter of the pupil
ciliary body
thickened region where the iris attaches
extends to the ora serrata
contains ciliary processes and ciliary muscle that attach the lens to the ciliary process
ora serrata
serrated anterior edge of the neural layer of the retina
choroid
vascular layer that separates fibrous and inner layers posterior to ora serrata
deliver oxygen and nutrients to retina
inner layer
made of the pigmented layer and neural layer
pigmented layer
contain pigment cells that support the function of photoreceptors in the neural layer
what kind of signal or chemical stimulates vision?
photons in 400 to 700 nm
where are photoreceptors found in the eye?
in the retina/neural layer
what are two types of photoreceptors?
cones and rods
what are the major functions of the eye?
what are the accessory structures of the eye and its functions?
rods
high sensitivity to light, help us to see in dim light room
cones
give us color vision, require more intense light
found in fovea at the center of macula
rod and cone information pathway
outer synaptic layer- bipolar cells - inner synaptic layer - ganglion cells - optic nerve
light pathway
cornea- anterior chamber- pupil- posterior chamber- lens- vitreous humor- retina
light refraction
occurs at the junction when light passes through a transparent substance that has one density, into another transparent substance with another density
where are images projected onto?
central fovea, where vision is the sharpest
astigmatism
the cornea/lens has an irregular curve causing distorted vision
myopia
nearsightedness, need a concave lens
image converges in front of retina (small eyeball)
hyperopia
farsightedness, need a convex lens
image converges behind retina (long eyeball)
rods and cones convert photoreceptors into
neural impulses
photopigments necessary for absorption of light initiate
production of a receptor potential
In the dark rods release what NT
Glutamate (inhibitory)
