The Special Senses

Front 1

Identify and describe the function of the three distinct cell types of the olfactory epithelium.

Back 1

Olfactory receptor cells - receptors, nerve cell, amnioric
Supporting cells - columnar epithelium: make up bulk of epithelial membrane, support, nourish, eletrically insulate nerve
Basal cells - stem cell; to regenerate olfactory receptor cells at base of epithelial membrane

Front 2

Olfactory receptor cells are an example of what type of neuron.

Back 2

Bipolar neurons - has thin apical dendrite which terminates in a knob covered w/numerous olfactory cilia (nonmotile/don't beat, lie flat on epithelium covered by thin layer of mucus)

Front 3

Identify the specific site of olfactory transduction.

Back 3

Odorant binding proteins - in olfactory receptor cells - each cell has only one type of OBP; odorants can bind to more than one OBP

Front 4

Are olfactory receptors considered to be rapid or slow adapting?

Back 4

Rapid adapting - complete w/in a minute

Front 5

Describe the process of transduction in an olfactory receptor cell.

Back 5

Odorant binds to Odorant Binding Protein
G-protein activation, cAMP formation, opening of cation channels
Ca (involved in adaptation) and Na (depolarizes membrane and creates receptor potential) enter,

Front 6

Trace the path of an olfactory impulse from the upper nasal cavity to the olfactory cortex and subcortical areas.

Back 6

Unmyelinated axons of olfactory receptor cells gathered in fascicles - form R+L olfactory nerves (CN I)
CN I projects through cribriform plate; synapse in olfactory bulbs
1st order axons converge on 2nd order
2nd order runs through olfactory tracts to:
- olfactory cortex in temporal lobe (conscious)
- subcortical route to hypothalamus, amygdala and lymbic system

Front 7

Identify and describe the 4 types of papillae found on the surface of the tongue.

Back 7

Fungiform - mushroom shaped, scattered over entire tongue, taste buds on top
Vallate papillae - largest and least common; form an inverted v @ back of tongue
Folliate papillae
Filiform - tactile receptors but no taste buds

Front 8

Which of the papillae on the tongue contain taste buds?

Back 8

Fungiform, vallate, foliate

NOT papillae

Front 9

Identify and describe the function of the three distinct cell types of a taste bud (all epithelial cells).

Back 9

Supporting cells - sensory dendrites coil around gustatory cells
Gustatory receptor cells - taste hairs and taste pores
basal cells - stem cells that make new gustatory receptor cells

Front 10

What part of the gustatory receptor cell is the stimulus transducer?

Back 10

- taste (or gustatory) hair - projects from each gustatory cell; receptor surface and synapse directly

Front 11

What are the five primary taste sensations?

Back 11

sweet
salt
sour
bitter
umami

Front 12

Which of the primary tastes is associated with a transduction process involving ion flow across the membrane of the gustatory hair? which apparently utilize a G protein-mediated mechanism?

Back 12

Ion flow - Salty due to Na influx; sour mediated by H influx and blockade of K
Bitter, sweet and umami mediated by G (gustducin) pritein dependent mechanism for depolarization

Front 13

Rank the activation thresholds for the primary tastes.

Back 13

Bitter detects in minute amounts, others are less sensitive - that's all there is in the book
thresholds vary for the different tastes

Front 14

Which cranial nerves are involved with gustation?

Back 14

CN VII - serves anterior 2/3 of tongue
CN IX - serves posterior 1/3 of tongue and pharynx
CN X - afferents from taste buds in epiglottis and lower pharynx

Front 15

Trace the gustatory pathway from taste buds to the gustatory cortex and subcortical areas.

Back 15

Taste buds - through the first order afferent fibers carrying taste info. (CN VII, IX, and X)
Synapse with second order neurons in solitary nucleus of medulla oblongata
From here, 2 routes: Thalamus - 2nd order synapses with 3rd order, 3rd order carry info to gustatory cortex in R+L insula (conscious); OR 2nd order pass to hypothalamus and limbic system (appreciation and satiety)

Front 16

Identify the general fuction of the following accessory structures of the eye: eyelids, eyebrows and eyelashes; conjunctiva; lacrimal apparatus (lacrimal glands, lacrimal canals and ducts); extrinsic eye muscles.

Back 16

Brows, lids and lashes: protection, keeps sweat etc out
Conjuntiva: covers sclera, lines upper and lower eyelids - protection from scratching
Lacrimal apparatus: glands - mucus, antibodies, lysosomore; ducts - drains excess lacrimal secretions into nasal cavity
Extrinsic eye muscles: tracking movements/motions of the eye; moving the eye back and forth

Front 17

Name the extrinsic eye muscles, describe their innervation, and tell what movements each produces.

Back 17

Rectus muscles - superior, inferior, medial lateral; (all oculomotor CN III, except lateral rectus which is abducens VI)
Superior oblique - rotates eye down and laterally (trochlea IV)
Inferior oblique - rotates eye up and laterally (also oculomotor III)

Front 18

Name the three layers of the wall of the eye from outermost to innermost.

Back 18

Fibrous tunic - sclera and cornea
Vascular tunic - choroid, ciliary body, iris
Sensory tunic - outer pigmented layer, inner neural layer

Front 19

Describe the general structure and function of each of the three layers of the wall of the eye.

Back 19

Fibrous tunic - dense avascular tissue. Sclera protects and shapes, anchor for extrinsic eye muscles, cornea = transparent anterior portion
Vascular tunic: pigmened to prevent scattering, has blood vessels, lymphatics, intrinsic eye muscles; choroid (blood and melanin), ciliary body (ciliary muscles to control lens shape, and ciliary processes that secrete anterior cavity fluid), iris (2 layers of smooth muscle to change size of pupil)
Sensory tunic: - outer pigmented layer (supports rods and cones, phagocytes and vit A stored, prevents light scattering), inner neural layer (rods and cones)

Front 20

What are the primary functions of the choroid?

Back 20

- part of the vascular tunic; blood vessel rich for nutrition
Melanin absorbs light and prevents scattering

Front 21

Describe the structural relationship b/w the ciliary body, ciliary processes, suspensory ligaments, and lens of the eye. How do these structures work together in accommodation.

Back 21

Ciliary body - thickened ring around the lens with ciliary muscles to contol the lens shape; ciliary processes come off it and contain capilaries that secrete fluid that fills anterior cavity
Suspensory ligament - goes from ciliary processes to lens
they all work to change the shape of the lens, and the amount that the light rays are distorted/affected
Ciliary body pulls on suspensory ligaments, ciliary processes put fluid in, which also changes the shape

Front 22

Describe the structure of the iris. How does the iris modify the amount of light that enters the posterior chamber of the eye?

Back 22

- 2 layers of smooth muscle fibers that change size of pupil:
Circular layer, causes constriction of pupil (close vision)
Racial layer causes dilation of pupil (distant vision)
Both controlled by ANS, constriction thru parasympathetic, dilation by sympathetic

Front 23

What muscle layer of the iris is under parasympathetic control? Sympathetic control?

Back 23

Parasympathetic - circular layer
Sympathetic - radial layer (dilation)

Front 24

Identify and locate (with respect to each other and to the eyeball as a whole) the two layers of the retina.

Back 24

Part of sensory, innermost tunic
Outer - pigmented layer; 1 cell thick abutting choroid and going anterior all the way to cover the ciliary body and posterior surface of iris
Inner - Neural layer - extends anteriorly to posterior margin of ciliary body; has rods and cones; very innermost layer

Front 25

What are the primary functions of the pigmented layer with respect to clear vision?

Back 25

Prevents light from scattering, stores Vit A, and act as phagocytes

Front 26

name the three distinct layers of retinal neurons from outermost to innermost.

Back 26

Photoreceptors - transducers:rods and cones
Bipolar cells - synapse with rods and cones
Ganglion cells, synapse with bipolar cells and generate ATP; exit via optic nerve

Front 27

Name and describe the specific functions of the two types of photoreceptors.

Back 27

Rods - sensative, dim-light and perifery visual
Cones - less numerous, higher threshold; provide color and sharper vision

Front 28

What region of teh retina produces the sharpest vision? why is acuity so high in this region?

Back 28

Macula lutea and fovea centralis
Only densly packed cones, becomes fewer, and more rods as you move further out
Retinal layers displaced here, so that light can fall directly on cones

Front 29

Why is the optic disk referred to as the "blind spot"?

Back 29

no photoreceptors, because that's where the optic nerve (CN II) exits the eye

Front 30

Where is aqueous humor located and what is its function?

Back 30

in front of the lens
composition similar to blood plasma; constant circulation for nutrient and waste transport
Filters from capilaries in ciliary processes into posterior chamber

Front 31

Where is vitreous humor located and what is its function?

Back 31

Posterior segment
transmits light, creates intraocular pressure to counteract extrinsic muscle forces, supports posterior surface of lens and hold neural retina firmly against pigmented layer

Front 32

What two eye structures account for virtually all of the eye's refractive ability?

Back 32

light goes from air into cornea
From aqueous humor to lens

So.. cornea and lens

Front 33

What is the functional significance of the far point of vision?

Back 33

- distance beyond which no change in lens shape is required for focusing
6m for a normal (emmetropic eye)

Front 34

Describe how the lens shape changes during accomodation for near vision.

Back 34

- Ciliary muscles contract, and processes release tension in suspensory ligaments, allowing lense to bulge; brings point forwards so it falls on the retina

Front 35

What is the functional significance of the near point of vision? Describe the typical age-related changes in the near point of vision.

Back 35

- closest point where we can focus clearly
- decrease in elasticity of lens as we age, so the near point of vision gets further and further away as we age, b/c it can't bulge as much when the suspensory ligaments let go

Front 36

Describe the abnormality in refraction which characterizes each of the following conditions: myopia; hyperopia; astigmasism.

Back 36

Hyperopia - farsightedness; distant objects focused behind retina b/c eyeball is too short; need convex lenses; can't see close
Mypopia - nearsightedness; can't see far; distant objects focused in front of retina; eyeball too long; concave lenses 4 treatment
Astigmatism - unequal curvatures in cornea of lens,

Front 37

Describe how the accommodation pupillary reflex and eyeball convergence contribute to clear and focused near vision.

Back 37

Pupil constriction - sphincter pupillae muscles of iris make pupil smaller to prevent most divergent light rays from entering eye and blurring vision
Convergence - cross eyed to keep object focused on retinal fovea

Front 38

Compare and contrast (structure and function) rods and cones.

Back 38

Rods - sensitive, single kind of visual pigment, so they see in gray; converging pathways (100 rods feed into 1 ganglion cell); summation, collectively fuzzy/indistinct
Cone - low sensitivity; 1 of 3 difft. pigments to see in color; each cone has own personal bipolar cell; detailed/high rex, more in fovea

Front 39

Name and describe the two parts of all photopigments.

Back 39

Retinal - photopigment, light absorber, made from vitamin A
Opsins - glycoprotein that combines with retinal to form photopigment, specialized for each cone and rod; allows for difft. absorption maxes; deep purple color (pigment called rhodopsin)

Front 40

Which of the two photopigments is the light absorbing part of the photopigment? which differs from one type of photopigment to another?

Back 40

light absorbing - retinal; made from Vit A
opsins - make rhodopsin when combined wit glycoprotein; 2 configurations; cis retinal in dark and transretinal in light

Front 41

Describe the cyclical pathway of photopigment bleaching and regeneration.

Back 41

cis to trans conversion of retinal; cis in dark and can form rhodopsin with opsin, trans in light and rhodopsin degenerated into the 2 parts
Trans retinal separates from opsin and pigment is bleached
Retinal isomerase converts trans back to cis; retinal shuttled into pigmented epithelium and ATP used to regenerate rhodopsin (when it binds with opsin)

Front 42

How does the release of activated opsin during the cyclical pathway of photopigment bleaching and regeneration alter the rate of NT release by photoreceptor cells?

Back 42

Dark - cyclic GMP binds to Na channels in outer segments, holding them open; depolarized
light triggers pigment breakdown, which activates several enzymes which break down cGMP so that the channels close = hyperpolarization and no NT release
Hyperpolarization is a positive signal, in this case

Front 43

What is the "dark current"? In darkness, what is the membrane potential of photoreceptor cells? What happens to its membrane potential when a photoreceptor cell s exposed to light?

Back 43

cGMP binds to Na channels so they are open and produces dark current; depolarized membrane
Membrane becomes hyperpolarized when light occurs, because cGMP is broken down, so the channels close

Front 44

Describe the path of light from teh point where it enters the eye until the photoreceptors are stimulated, noting each structure through which the light passes.

Back 44

cornea, aqueous humor, through pupil to lens, into vitreous humor and onto the Inner neural layer, where the photoreceptor cell is exposed to the light, after that, the path of the info is opposite that of the light

Front 45

What structures constitute the outer ear? the middle ear? the inner ear?

Back 45

Outer - auricle/pinna, external accoustic meatus, tympanic membrane is border
Middle - ossicles: maleus, incus, stapes; tensor tympani, stapedius
Inner - vestibule, cochlea, semicircular canals

Front 46

Name the auditory ossicles and describe their position within the middle ear

Back 46

Maleus, incus, stapes
Transmit and amplify vibrations from tympanic membrane to oval window
In middle ear

Front 47

Describe the process through which the tympanic membrane and ossicles work together to trasmit and amplify sound waves?

Back 47

Tympanic membrane - all sound waves are concentrated on it from outside
17-20 times smaller - the oval window that the ossicles transmit it to.

Front 48

Identify the two muscles of the middle ear and describe their function.

Back 48

Tensor tympani - pulls eardrum tight
Stapedius - limits movement of stapes in oval window
Contract when loud noises occur to limit damage to hearing receptors

Front 49

What two regions are connected by the auditory tube? How does the auditory tube contribute to hearing?

Back 49

links middle ear with nasopharynx/superior part of throat
equalizes air pressure, so that the tympanic membrane can vibrate freely

Front 50

Identify and locate with respect to each other the three unique regions of the bony labyrinth.

Back 50

Vestibule - central cavity of bony labyrinth; lateral wall is oval window; 2 membranous sacs suspended in fluid + connected by small duct (saccule and utricle)
Cochlea - extends from vestibule and coilds around bony core; a spiral
Semicircular canals - swelling/ampulla attatched at base to vestibule

btw. filled with perilymph, a fluid

Front 51

Identify and locate (with respect to each other and to the bony labyrinth) the various parts of the membranous labyrinth.

Back 51

Continuous series of membranous sacs and ducts within bony labyrinth; filled with endolymph
Scala media - the cochlear duct, inferior to the scala vestibuli and superior to the scala tympani
Saccule and utricle - 2 sacs in vestibule
semicircular duct - one within each of the canals; duct has a swelling called an ampulla which contains the equ. receptor - the crista ampularis

Front 52

Where is perilymph located? endolymph?

Back 52

Perilymph - in scala vestibuli and scala tympani
Endolymph - in scala media (the cochlear duct)

Front 53

Describe the internal structure of the cochlea. Note the location of cochlear structures with respect to the oval and round windows. Where in the cochlea is endolymph locatee

Back 53

Scala media - the cochlear duct, inferior to the scala vestibuli and superior to the scala tympani
hick at it's base near the oval window, and thinner/wider near apex of cochlea
Basillar membrane separates scala media from scala tympani - supports organ of corti - t
4 rows of hair cells (1 inner, 3 outer), with stereoclia protruding from apical tip of hair cell, into K righ endolymph, longest ones are enmeshed in tectorial membrane
Afferent nerve fibers coil around bases of hair cells

Front 54

Describe the organ of Corti, noting its relationship to the basilar and tectorial membrane

Back 54

Sits on top of the basilar membrane, which separates the scala media from the scala tympani
made of supporting cells and hair cells, hairs have 1 stereocilia potruding from apex into perilymph, and longest ones into tectorial membrane, which is gel-like

Front 55

Describe the hair cells of the organ of corti. How does a hair cell transduce a stimulus?

Back 55

the stereocilia come out of apical tip of hair cell into endolymph and tetctorial membrane Basillar membrane vibrates, and causes vibration of hair cells agains tectorial membrane; creates receptor potential:
High K conc. in endolymph, so K flows into hair cell, depolarizing and increasing rate of NT release by hair cell

Front 56

Describe the events involved in transducing sound vibrations, beginning with a sound wave passing through the external auditory canal.

Back 56

Auricle directs waves into external auditory canal
Tympanic membrane vibrates and auditory ossicles (malleus, incus, stapes) amplify it
Oval window creates press. waves in perilymph of vestibular duct and perilymph of cochlea
Pressure waves go from scala vestibuli to scala tympani - their vibration makes vestibular membrane vibrate
Pressure waves in endolymph in cochlear duct cause basilar membrane to vibrate in certain region
Causes hairs to vibrate against tectorial membrane, letting flow of K into cell; depolarizes and increases rate of NT release
CN VIII (which is coiled at the base of hair cells) sends info on intensity and region of stimulation to CNS

Front 57

How are frequency and intensity of sound vibrations encoded by the organ of Corti?

Back 57

Intensity - the degree of hair cell distortion
Frequency - a certain region (at the location of maximum displacement) the basillar membrane vibrates;high frequency displace it close to the base, low frequency displace it further away.

Front 58

Follow the auditory pathway from the sensory afferents at the base of the hair cells to the auditory cortex and subcortical areas.

Back 58

CN VIII (vestibulocochlear) is coiled around base of hair cells, and sends it to CNS:
cell bodies of tehses bipolar sensory neurons are found in modiolus in spiral ganglia
Axons synapse in cochlear nuclei in medulla
impulses sent to superior olivary nucleus (pons-medulla jct), then via lateral lamniscal tract, to inferior colliculus (midbrain)
Then via thalamus to auditory cortex
Reflexes to sound: inferior colliculus also sends input to superior colliculus to act together

Front 59

Identify and define the two types of equilibrium.

Back 59

Dynamic - rotational movements of head; provided by semicircular ducts
Static - position of head with respect to gravity; provided by saccule and utricle

Front 60

Which vestibular structure(s) are associated with dynamic equilibrium? with static equilibrium?

Back 60

Dynamic - semicircular canals
Static - saccule and utricle

Front 61

Identify and describe the function of the two types of cells in the maculae of the utricle and saccule.

Back 61

Hair cells - numerous sterocilia andone kinocilium from apical surface, embeded in otolithic membrane; utricle - hairs vertical; saccule - hairs horizontal
Otholiths/statconia - calcium carbonate crystals in otolithic membrane to increase membraine's weight and inertia; a supporting cell

Front 62

How does the otolithic membrane contribute to stimulation of the hair cells of the macula?

Back 62

- It's weighted down by otoliths, so it has more inertia
- the kinocilium potruding from the apical surfaces of the hair cells are embedded in the otolithic membrane

Front 63

Describe the process through which head movement creates a receptor potential or repolarization of the macular hair cells.

Back 63

Hair cells release NT continually; movement of hairs modifies the secretion rate
Otolithic membrane moves and bends hair cells
Endolymph with high K, so K flows into cells and depolarizes
hair cell is depolarized, and increases the rate of NT

Front 64

Describe the relationship of the semicircular canals with respect to each other.

Back 64

all are continuous with the utricle
- in ampulla of each duct, there is crista ampullaris (with supporting cells and hair cells)
Kinocilia and steriocilia embedded in gel called cupula
B/c of orientation, rotation in any direction causes depolarization in one ampulla and hyperpolarization in another

Front 65

Where are the cristae located?

Back 65

- small elevation at the ampulla of each duct
- semicircular canals continuous with utricle
- dendrites encircle base of hair cells

Front 66

Identify and describe the function of the hair cells and cupula of the cristae.

Back 66

Hair cells have kinocilia and stereocilia ; embedded in cupula
endolymph pushes cupula so that it moves in opposite direction of body's rotation at first
Cupula movement one way depolarizes the hairs, movement the other way hyperpolarizes them

Front 67

How is a rotational movement stimulus transduced?

Back 67

Head rotates, endolymph moves opposite direction for a moment
Endolymph pushes cupula which bends hairs of hair cells in crista
Depending on the direction pushed, hairs are either depolarized or hyperpolarized
always de- in one ampulla and hyper in another - no matter what direction you rotate

Front 68

Which cranial nerve conducts sensory nerve impulses regarding static and dynamic equilibrium?

Back 68

CN VIII - vestibulocochlear nerve
The vestibular branch

Front 69

Olfactory cilia

Back 69

lie flat on nasal epithelium, covered by thin layer of mucus
Contain OBP
the thin apical dendrite of an olfactory receptor cell (a bipolar neuron)

Front 70

Olfactory tract

Back 70

formed by the axons of olfactory bulb neurons
the path it takes, all the way up

Front 71

Olfactory Nerves

Back 71

synapse with mitral cells in glomeruli
the primary afferant nerve

Front 72

presbyopia

Back 72

old people's eyes
when the lens is less resilant

Front 73

modiolus

Back 73

the spongy bone that the cochlea turns 2.75 times around

Front 74

emmetropic

Back 74

when the eye is relaxed and the object is in focus - the object is over 6 m away

Front 75

amacrine cells

Back 75

helps modify impulse tramsmission by ganglion cells (M cells for rods and P cells for cones)
- excited by bipolar cells via gap jct.
local integrator neurons
modify and direct impulses

Front 76

Horizontal cells

Back 76

helps modify impulse tramsmission by ganglion cells (M cells for rods and P cells for cones)
- lateral inhibition
- gets info via gap jct.
- allows retina to convert points of light into perceptualy more meaningful contour by accentuating bright/dark or color contrasts

Front 77

Where are the photopigments located?

Back 77

- in membrane discs (rods) or folds (cones) of outer segment, which is embedded in the pigmented layer of the retina
These discs/folds at the tip of the photoreceptor continually fragment off
Cones - discs are continuous w/plasma membrane
Rods - disks are discontinuous
Disks = membrane enclosed structures where photopigments are located

Front 78

Describe the structure of photoreceptor cells.

Back 78

see p 561 for image
Photoreceptor= rods and cones
- have outer segment and inner segment
- Outer: embedded in pigmented layer; receptor with photopigments embedded in membrane discs (rods) or discontinuous folds (cones); increase SA
Inner segment in neural layer of retina connected to outer by thin stalk w/cillium; has cell body: nucleus, mitochon, organelles, ATP product. photopigment synthesis, etc; Has process that ends in synaptic terminal to synapse with bipolar cell

Front 79

Explain the basic processing of visual input that occurs in the retina.

Back 79

Light passes through vitreous humor and passes through neural layer; in the pigmented layer, excess light is absorbed, and some light is "taken up" by the outer segment of the photoreceptor cells (modified neurons),
This segment contains discs with photopigments embedded in the membrane discs that change shape as they absorb light.

Front 80

Continue to follow the path of the visual stimulus as it is transduced to an electrical impulse by the photoreceptors of the retina, and carried from the eye to the brain.

Back 80

Light hits photopigments and is absorbed by retinal; it changes teh shape of opsin, so that it is trans instead of cis
Rhodopsin falls apart, bleaches its purple pigment and triggers chain that eventually breaks down cGMP
No cGMP = Na channels close, ending dark current and causing hyperpolarization and stop to NT output
Synapse from photoreceptor to bipolar cell, then from bipolar cell to ganglion cell; retinal ganglion cells converge on optic disc and are carried rom the eye in CN II (optic n)
Medial fibers cross over at optic chiasma
optic tracts to lateral geniculate nuclei of thalamus (ballanced and combined)
thalamic neurons through internal capsule, form optic radiation to primary visual cortex of occipital lobes
Also, collaterals to superior colliculi of midbrain (reflex centers) and suprachiasmatic nucleus of hypothalamus (biorhythms)
Finally - association areas