special senses Flashcards
how does Olfaction occur?
Nose house cillia which bind to the ordorant ( generate a summative receptor potential) GPCR ( NA+/k+ channels open, they connect w mitra cells in the glomerulus region to for CN1.
- olfaction directly involves the limbic system and the amygdala
Rods:
densely populated in the outer areas of the retina, they are sensitive to light levels & give use good vision in dim lighting.
Cones
most concentrated in the fovea a, best for colour and highest visual acuity.
phobia:
very small part of the retina w some cones w/ more rods surrounding.
how do photoreceptors work
light enter the eye( lens/cornea)–>image=flipped at the back of the eyeball–> depolarization occurs—-> rods & cones synapes (glomerulus) making CN2—> they change shape–>Cis retinal transitions–> transretinal (activates G protein–> cascade reduces glutamate–> less Na+ channels close ( hyperpolarization)—> less glutamates released off bipolar cells
left side of visonary feild can pick up info from____ in addition to the left side( vice/versa)
right side, info crosses over at the optic chiasm
what CN control seeing and eye movement?
CN 2,3,6
outer ear anatomy
pinna/auricle ( lobe), External acoustic meatus (ear canal), temporal bone
middle ear structures:
tympanic membrane, Maleus, Incus, & scapes
Inner ear structures:
cochlea, utricle, & saccule, semicircular canals, vestibular apparatus–> CN8–> primary acoustic cortex
sclera:
whites of the eyes
a tough fibrous coat…
the outer layer of the eye
cornea….
a transparent bulg that allows light to pass through it
uvea…
middle layer of the eye, dark and vascular layer near the sclera
cilliary body….
made up of ciliary muscles that control the shape of the lens to help it focus on near/distant objects
iris
circular structures surrounding the pupils
lens
transparent biconvex surrounded by an elastic capsule
retina
inner walls of the eyes and is pigmeneted ( several layers of neurons)
Fovea:
has many cones & provides most acute/colour vision
virtuous humor:
stored in the posterior cavity, holds the retina against the choroid & keeps the shape and size
aqueous humour
from the anterior cavity continuously secreted by the ciliary process, supplies the eye w nutrients ( lens, cornea; b/c they lack bf)
Visual pathway:
Light rays pass through the cornea + are refracted→ aqueous humour & pupil.( curvature of lens = adjusted to refract light)
Light converges on retina( sharper image), rods& cones= stimulated here
Light energy→ electrical stimulus—-> optic nerve—> occipital lobe int he brain
Image is identified and analyzed
what are the 6 muscles that control the movement of the eyes?
4 straight ( rectus) muscles
2 angled oblique muscles
myopia
nearsightedness, close objects=blurry ( corrected w concave glasses that lenses change when in dim lightning
Hyperopia
objects far away are blurry, lens=convex to focus rays o the retina
astigmatism
irregular curvature of the lens or cornea
presbyopia
inability of the lens to accommodate view while moving closer tot he eyes
(most common in elderly)
diplopia
double vision
eye movement= controlled by what nerves?
CN3,4,6
strabismus:
caused by neuro defects or hypertonic muscles/muscle lengths that do not allow the eyes to focus images on the retina, blurred vision
- if not fixed brain becomes blined to image produced by that eye
Tx: surgery/exercises
Nystagmus
involuntary jerky movements of the eyes
conjunctivitis
pink eye bacterial/viral/fungal infection, inflammation of the conjunctivia–> can have serous/purulent exudate, itchiness
glaucoma
increased Intraoccular pressure
1) trabecular network= unable to drain and pushes against the retinal cells
- insidious onset, tunnerl vision, clolourvision= not affected until later
narrow angle glaucoma (acute)
cannal of schlemm becomes more narrow stopping th eback flow of fluid
- rapid onset, +IOP, discomfort, pupillary response,
tx: miotics
cataracts
due to a protein build up on the optic lens
- blurred vision, easier to see at night time, cuased by diabetes, no eye protection
tc: surgery/replacement
retinal dettachment
exudative: fluid moves through the capillaries ( separates the retina from the cornea)–> permentant vision loss
tanctional: fibrosis occurs between the layers of the retina & cornea
spontaneous: when the biterous fluid decreases
- spots, blurred vision, painless
diabetic retinopathy
blood cells change shapes and clot in the retina–> leaky mature BV–> retinal dettahcment
age related macular degeneration
scarring fibriotic tissues int he fovea centralis ( colour vision/acuity)
atrophic dry :protiens deposit and damage
atrophic wet: large number of leaking blood cells between cornea & retinal layer–> blindness
macular degeneration
-acute, painless, occurs when the retina tears away from the underlying choroid due to marked myopia, viterous humor leaks behind loos retina, retinal cells stop working bc they loose nutrient supply
conductive hearing loss
impact of cermen on the tympanic membrane
ex: qutips
sensorineural hearing loss
Cn8 problems, due to toxic meds, loud noises, metanolic disorders
Otitis media
infection of the middle ear
- makes exudate narrowing ofthe stuachin tube—> scarring permenat damage
- pain, hearing loss
mineres disease
autoimmune, excess endolymph in the cochlea & vestibular organs & change the function of the hairs in the ears
-vertigo, tinnitus, nystagmus
utricle and saccule functions….
static equilibrium—> position of head relative to gravity, involved in deccleration
dynamic equillibrium organs…
semicircular ducts, balance gead & body= rotated suddenly
vestibule apparatus
measures linear acceleration in the verticle ( saccule) and horizontal (utricle) planes
