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Ch. 17 The Special Senses
Anatomy
74
Anatomy
Undergraduate 3
02/01/2014

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Cards

Term
What type of sense is olfaction and what are receptors associated with olfaction?
Definition
Chemical, "hairs" or cilia in which there are about 10-100 million in superior portion of nasal cavity.
Term
What are support cells associated with olfaction?
Definition
Columnar epithelium and bowman's glands.
Term
What is the threshold and adaptation of olfaction like?
Definition
Theshold is low, adaptation is rapid, some strong odors are completely ignored in 1 minute.
Term
What is the neural pathway for olfaction?
Definition
Cranial nerve I to olfactory bulb to olfactory tract to limbic system/hypothalamus to cerebral cortex, only sensory system that does not synapse in thalamus before sending signals to cerebrum.
Term
What type of sense and what receptors are associated with gustation?
Definition
Chemical (closely related to smell), gustatory cells with single long cilia projection (50 per taste bud and 10,000 buds total).
Term
What are the 5 primary tastes and the highest and lowest threshold of those tastes and quickness of adaptation?
Definition

1. Sour

2. Sweet

3. Bitter

4. Salt

5. Umami

Adaptation is within 1-5 mins, bitter has lowest threshold, salt and sweet have highest threshold.

Term
What is the neural pathway for gustation?
Definition
Cranial nerves VII/IX/X to the medulla to the limbic system/hypothalamus/thalamus, then thalamus to cerebral cortex.
Term
What is another name for eyelids and what are their functions?
Definition
Palpebrae, shade during sleep, protect from excessive light/foreign objects, spread lubricant over eyeball.
Term
What is the conjuctiva?
Definition
Mucous membrane that covers inner surface of eyelids and surface of eyeball up to cornea, conjuctivitis is when the cappilaries dilate due to infection or irritation.
Term
Describe functions of the eyelashes and eyebrows.
Definition
Eyelashes protect from foreign objects/perspiration/direct sunlight rays, eyebrows protect from foreign objects/perspiration/direct sunlight rays.
Term
What is the choroid of the eye?
Definition
Most posterior portion, most of inner surface of sclera, provides nutrients to posterior part of retina, highly vascular.
Term
What is the ciliary body of the eye?
Definition
Extends from anterior edge of retina to junction of cornea and sclera, contains: ciliary processes which secrete aqueous humor, suspensory ligaments which attach to lens, and ciliary muscles which are circular smooth muscle that alters shape of lens.
Term
What is the iris of the eye?
Definition
Colored portion of eyeball, consists of radial and circular smooth muscle, regulates pupil size.
Term
Talk about iris color.
Definition
Many different genes contribute to color, no discrete colors of human eyes, spectrum of colors between blue and brown, iris in a single person has many different colors in it, color results from combination of yellow and black.
Term
What are the pigment epithelium of the retina?
Definition
Lies between choroid and neural portion, melanin absors light and prevents reflection/scattering of light within eyeball.
Term
What is the lacrimal apparatus of the ye?
Definition
Produces and drains tears, duct which empties onto conjuctiva, collects in lacrimal puncta, drains into nasal cavity.
Term
What is the diamater of the eyeball and the 3 layers?
Definition

Diamater: 1 inch

Fibrous tunic: outer layer - avascular, includes cornea/sclera

Vascular tunic: middle layer, includes choroid/ciliary body/iris

Nervous tunic: inner layer, includes retina

Term
What is the cornea?
Definition
Transparent covering of iris, helps refract light.
Term
What is the sclera?
Definition
White of the eye, dense connective tissue, gives shape and rigidity to eyeball.
Term
What is the neural portion of the retina, including the 3 layers?
Definition

Outgrowth from brain, three layers:

1. Photoreceptor layer (inner)

2. Bipolar cell layer (middle)

3. Ganglion cell layer (outer)

Light passes through ganglion and bipolar layers to reach photoreceptors, blind spot is optic disc where optic nerve exits eyeball, macula lutea is central part of posterior retina, central fovea is in center of macula lutea.

Term
What is the lens?
Definition
Posterior to pupil, avascular, made of proteins called crystallins and enclosed by clear connective tissue, normally transparent, held in place by suspensory ligaments.
Term
What is the anterior cavity of the interior of the eyeball like?
Definition
Contains anterior chamber and posterior chamber, filled with aqueous humar, replaced every 90 mins, produces introcular pressure but if too much can lead to glaucoma.
Term
What is the posterior cavity of the interior of the eyeball like?
Definition
Between lens and retina, contains vitreous body which is jellylike and pushes retina against choroid/maintains eyeball shape, not continually replaced, contains phagocytic cells which remove debris to clear vision.
Term
What are the 3 components of image formation?
Definition
Refraction, accomodation, constriction.
Term
What is refraction?
Definition
Bending of light rays as they enter eye, 75% corneal refraction and 25% lens, image inverted on retina so left goes right and vice versa, bent rays focus on central fovea.
Term
What is accomodation including the near point?
Definition
Increased curve on back side of lens to focus on near objects, less tension on suspensory ligmanets, near point is minimum distance at which eye can focus.
Term
What is constriction?
Definition
Narrowing of the pupil eliminates peripheral rays for finer focus, occurs simultaneously with accommodation and also in brighter light.
Term
What is convergence?
Definition
Medial movement of both eyes to focus on same object, results in binocular vision for better depth perception.
Term
What are the 2 photoreceptors?
Definition
Rods and cones.
Term
Describe the structure of photoreceptors.
Definition

Outer segment: transduction of light energy into receptor potential occurs, photopigments, folded plasma membrane or discs

Inner segment: cell body, axon, mitochondria, golgi complex

Term
What are photopigments?
Definition
Colored pigments that absorb light, rhodopsin absorbed by rods, blue/green/red absorbed by cones, all photopigments contain opsin (glycoprotein) and retinal (a light-absorbing protein)
Term
What is the 4 step process of the photopigment response to light?
Definition

1. Cis (bent) goes to trans (straight) retinal when hit by light which produces unstable chemicals

2. 1 min later trans-retinal separates from opsin

3. Retinal isomerase converts trans-retinal to cis-retinal

4. Cis-retinal binds to opsin

Term
Describe th two adaptations from light to dark and from dark to light.
Definition

Dark to light: fastĀ 

Light to dark: slow

Term
What are a couple photoreceptor abnormalities?
Definition

Color blindness: cone defects

Nyctalopia: poor night vision

Term
What are the functions of the rods in retinal processing?
Definition
Low light threshold, very sensitive, black/white, slow regeneration process, contribute little to daytime vision, affects night vision.
Term
What are the functions of cones in retinal processing?
Definition
High light threshold, less sensitive, color, main source of vision, cones regenerate faster than rods.
Term
What are the functions of neurotransmitters in retinal processing?
Definition
Glutamic acid, inhibitory neurotransmitter, triggers IPSPs, hyperpolarization of bipolar cells, inhibit sending signal to ganglion cells.
Term
What are the functions of horizontal cells in retinal processing?
Definition
Transmit lateral inhibitory siganls from photoreceptors to bipolar cells located laterally to rods/cones, enhances contrast and color discrimination, located in bipolar cell layer.
Term
What are the functions of excited bipolar cells in retinal processing?
Definition
Light causes Na+ channels to close, decrease glutamic acid release from rods/cones to bipolar cells, lose IPSP which means an AP is generated which induces graded potentials in bipolar and horizontal cells, thus light excites bipolar cells by turning off the release of inhibitory neurotransmitter.
Term
What are the functions of amacrine cells in retinal processing?
Definition
Excited by bipolar cells then synapse with ganglion cells, signal change in light intensity, modify ganglion cell responses to bipolar cell stimuli, located in bipolar cell layer.
Term
What are the functions of ganglion cells in retinal processing?
Definition
Become excited by signals from bipolar or amacrine cells, initiate nerve impulse in optic nerve.
Term
What is the neural pathway for vision and what types of neurons are involved?
Definition

Sensory axons involved, optic nerve goes to optic chiasm then goes to thalamus then goes to visual cortex, incomplete decussation, 3 areas in cortex analyze vision:

1. Shape

2. Color

3. Movement/location/spatial arrangement

Term
How much faster does transduction occur in sound than light?
Definition
1000x
Term
Describe the parts and structure of the external ear.
Definition
Auricle is a helix/lobule, external auditory canal is 1" long/curved/has some hairs/ceruminous glands which secrete earwax, eardrum here.
Term
Describe the parts and structure of the middle ear.
Definition

Air-filled cavity, bound by eardrum and oval round windows 3 auditory ossicles with synovial joints:

1. Malleus (hammer)

2. Incus (anvil)

3. Stapes (stirrup)

Eustachian tube helps with pressure equilibrium and is route for pathogens to travel from nose/throat to middle ear.

Term
Describe the parts and structure of the inner ear.
Definition

Semicircular canals: equilibrium, 3 oriented at 90 degree angles

Vestibule: equilibrium, contains utricule and saccule

Cochlea: hearing

Perilymph: surrounds membranous labyrinth

Term
Describe the physiology of hearing in relation to the physics of sound.
Definition
Audible spectrum of 20 - 20,000 Hz, membranes closest to oval window respond to high frequencies, those closer to round window respond to low frequencies, 90 dB or higher is dangerous for hearing, 140 dB is painful.
Term
What is the order in which sound goes through the ear?
Definition
External auditory canal to the tympanic membrane to the middle ear ossicles to the oval window to the round window to the vestibular membrane to the basilar membrane to the tectorial membrane which bends hair cells which activates cochlear nerve impulses.
Term
What is the neural pathway for hearing?
Definition
First order neurons in cranial nerve VIII go to medulla then go to pons then go to midbrain then go to thalamus then go to cortex.
Term
What are the two kinds of equilibrium in hearing and what parts are involved?
Definition
Static and dynamic, vestibular apparatus is involved, vestibular apparatus components include otolithic organs and semicircular ducts.
Term
What are the functions, components, physiology, and nerve of the otolithic organs?
Definition
Functions include primary static equilibrium/dynamic equilibrium/position of head/maintain posture and balance, components include saccule and utricle, physiology includes otoliths in otolithic membrane interacting with hair cells, nerve is cranial nerve VIII
Term
What are the functions, components, physiology, and nerve of the semicircular ducts?
Definition
Functions include dynamic equilibrium, components include ampullae with elevations/cupula/hair cells, physiology includes endolymph flow moving from cupula which bends hairs and creates potential, nerve is cranial nerve VIII.
Term
What is glaucoma?
Definition
High intraocular pressure due to buildup of aqueous humor, most common U.S. cause of blindness, destruction of retina, painless so much damage happens before detected, risk factors include age/ethnicity/genetics/previouse eye injuries and disease.
Term
Describe the 2 main ways deafness occurs.
Definition

Sensorineural: damage to cochlear hair cells or damage to cranial nerve VIII, cause include atherosclerosis/aspirin/streptomycin/loud noise, treated with cochlear implants

Conduction: impairment of external or middle ear mechanisms for transmitting sounds to inner ear, otosclerosis, impacted cerumen, eardrum injury, aging.

Term
What is meniere's disease?
Definition
Too much endolumph, enlarged membranous labyrinth, intermittent hearing loss, roaring tinnitis, vertigo, complete hearing loss over period of years.
Term
What is senile macular degeneration?
Definition
Leading cause of blindness for people over 75 years of age, destruction of macular region of retina, lose acute vision but reatin peripheral vision, some not treatable but others can with laser destruction of blood vessels, smoking is a risk.
Term
What is otitis media?
Definition
Acute middle ear infeciton, bacteria from nose and throat, pain/malaise/fever/red swollen eardrum, may rupture, buildup of pus in middle ear, more in children.
Term
What is motion sickness?
Definition
Accelerations in different directions or loss of visual contact with horizon, confilcts of visual clues and equilibrium, fear makes it worse, dizziness/fatigue/nausea/vomiting.
Term
What is achromotopsia?
Definition
Total color blindness.
Term
What is ageusia?
Definition
Loss of sense of taste.
Term
What is amblyopia?
Definition
Loss of vision in otherwise normal eye.
Term
What is anosmia?
Definition
Loss or impairment of sense of smell.
Term
What is blepharitis?
Definition
Inflamed eyelids.
Term
What is conjunctivitis?
Definition
Pinkeye, redness of conjuctiva.
Term
What is keratitis?
Definition
Corneal inflammation or infection.
Term
What is nystagmus?
Definition
Rapid jerky eye movements.
Term
What is otalgia?
Definition
Earache.
Term
What is ptosis?
Definition
Drooping of upper eyelid.
Term
What is retinoblastoma?
Definition
Most common childhood intraocular cancer.
Term
What is scotoma?
Definition
Area of diminished vision within the field of vision.
Term
What is strabismus?
Definition
Visual disorder where eyes are misaligned and point in different directions.
Term
What is tinnitis?
Definition
Ringing ears.
Term
What is trachoma?
Definition
Caused by chlamydia, leading cause of blindness worldwide.
Term
What is vertigo?
Definition
Disordered state in which the individual or the individual's surroundings seem to whirl dizzily.
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