Chapter 16: The Special Senses

Front 1

special sensory receptors

Back 1

localized in head region; receptor cells

Front 2

receptor cells

Back 2

neuron like epithelial cells or small peripheral neurons that transmit sensory info to other neurons in afferent pathways to the brain

Front 3

chemoreceptors

Back 3

receptors that respond to chemical substances (receptors for taste and smell)

Front 4

taste buds

Back 4

in mucosa of mouth and pharynx; contain taste receptors; globular collection of epithelial cells; contains two cell types: gustatory and basal epithelial cells

Front 5

fungiform papillae

Back 5

projections of the tongue mucosa; have taste buds on apical surface

Front 6

vallate papillae

Back 6

near back of tongue; have taste buds on side walls

Front 7

gustatory hairs

Back 7

long microvilli extending from the gustatory epithelial cells through a taste pore; molecules bind to its plasma membrane

Front 8

gustatory epithelial cells

Back 8

cells in taste bud; generate impulses to sensory nerve fibers that innervate them

Front 9

gustatory pathway

Back 9

the pathway that taste info takes to reach the brain stem and cerebral cortex; follows two cranial nerves (facial and glossopharyngeal)

Front 10

olfactory epithelium

Back 10

covers superior nasal concha and part of nasal septum; contain receptors for smell; pseudostratified columnar epithelium

Front 11

olfactory sensory neurons

Back 11

bipolar neurons in the olfactory epithelium; replaced continuously; receptor cells that have an apical dendrite that projects to the epithelial surface with an olfactory cilia radiating from it; axons enter ct of lamina propria and gather into nerve bundles

Front 12

olfactory cilia

Back 12

receptive structures of smell; odor molecules bind to their plasma membrane

Front 13

filaments of the olfactory nerve

Back 13

nerve bundles formed by axons of olfactory sensory neurons; penetrate cribiform plate of ethmoid bone and enter olfactory bulb

Front 14

olfactory bulb

Back 14

in forebrain; olfactory nerve axons branch and synapse with neurons (mitral cells)

Front 15

mitral cells

Back 15

relay olfactory info to other parts of brain; transmit impulses along olfactory tract to limbic region and piriform lobe of cerebral cortex

Front 16

glomeruli

Back 16

complex synaptic clusters in the olfactory bulb

Front 17

lacrimal caruncle

Back 17

reddish elevation in medial angle of eye; contain glands

Front 18

tarsal plates

Back 18

ct structures that support the eyelids

Front 19

levator palpebrae superior

Back 19

voluntary skeletal muscle that opens the eye; in upper eyelid

Front 20

tarsal glands

Back 20

modified sebaceous glands in the tarsal plates; release oil that lubricates eye

Front 21

conjunctiva

Back 21

transparent mucous membrane covering the inner surfaces of the eyelids (palpebral conjuctiva) and anterior surface of eye (bulbar conjunctiva)

Front 22

conjunctival sac

Back 22

slitlike space that is formed between eye surface and eyelids when eyes are closed

Front 23

lacrimal apparatus

Back 23

keeps surface of eye moist with lacrimal fluid; gland and ducts that drain lacrimal fluid into nasal cavity

Front 24

lacrimal gland

Back 24

in orbit superolateral to the eye; produces lacrimal fluid

Front 25

lacrimal punctum

Back 25

small opening in medial angle of eye

Front 26

lacrimal canaliculus

Back 26

small tube in lacrimal punctum;

Front 27

conjunctival sac

Back 27

slitlike space that is formed between eye surface and eyelids when eyes are closed

Front 28

lacrimal apparatus

Back 28

keeps surface of eye moist with lacrimal fluid; gland and ducts that drain lacrimal fluid into nasal cavity

Front 29

lacrimal gland

Back 29

in orbit superolateral to the eye; produces lacrimal fluid

Front 30

lacrimal punctum

Back 30

small opening in medial angle of eye

Front 31

lacrimal canaliculus

Back 31

small tube in lacrimal punctum;

Front 32

lacrimal sac

Back 32

in medial orbital wall; lacrimal fluid drains here

Front 33

nasolacrimal duct

Back 33

carries lacrimal fluid from lacrimal sac to nasal cavity

Front 34

6 extrinsic eye muscles

Back 34

lateral rectus
medial rectus
superior rectus
inferior rectus
superior oblique
inferior oblique

Front 35

trochlea

Back 35

ligamentous sling that is suspended from the frontal bone in orbit roof; superior oblique muscle runs through this

Front 36

3 layers of the eye

Back 36

fibrous
vascular
inner

Front 37

sclera

Back 37

in fibrous layer of eye; opaque white part of eye; protects eyeball and provides shape

Front 38

cornea

Back 38

anterior part of fibrous layer; transparent and allows light to enter eye; forms part of light bending apparatus of the eye; has nerve endings that are pain receptors

Front 39

choroid

Back 39

pigmented membrane in vascular layer; blood vessels nourish other layers of eye; contains melanocytes; melanin absorbs light and prevents scattering of light

Front 40

ciliary body

Back 40

continuous with choroid in vascular layer; thickened ring of tissue encircling lens

Front 41

ciliary muscle

Back 41

smooth muscle that focuses the lens

Front 42

ciliary processes

Back 42

posterior surface of ciliary body near the lens;

Front 43

ciliary zonule

Back 43

fine fibrils extending from ciliary processes and attaching to the lens

Front 44

iris

Back 44

visible, colored part of eye; between cornea and lens; consists of smooth muscle fibers (sphincter and dilator pupillae) that vary size of pupil

Front 45

pupil

Back 45

round, central opening of iris; allows light to enter eye

Front 46

retina

Back 46

in inner layer of eye; made of 4 layers: pigmented, photoreceptor, bipolar cell and ganglion cell

Front 47

pigmented layer of retina

Back 47

outer layer, next to choroid; contains melanocytes; absorbs light and keeps it from scattering in the eye

Front 48

photoreceptor cells

Back 48

rod cells and cone cells; considered neurons, but actually epithelial cells

Front 49

rod cells

Back 49

sensitive to light and permit vision in dim light; do not provide sharp images or color

Front 50

cone cells

Back 50

functions best in bright light and permit high acuity color vision

Front 51

ora serrata

Back 51

junction where neural layer joins with ciliary body

Front 52

macula lutea

Back 52

lies on eye's posterior pole on retina; contains mostly cones

Front 53

fovea centralis

Back 53

small spot on macula lutea; only cones; provides maximal visual acuity

Front 54

optic disc

Back 54

circular elevation where axons of ganglion cells converge to exit the eye as the optic disc; blind spot

Front 55

vitreous humor

Back 55

jellylike substance in posterior segment of eye; transmits light, supports posterior surface of lens , helps maintain intraocular pressure

Front 56

anterior segment of eye

Back 56

in front of lens and ciliary zonule; filled with aqueous humor

Front 57

anterior chamber of eye

Back 57

between cornea and iris

Front 58

posterior chamber of eye

Back 58

between iris and lens

Front 59

aqueous humor

Back 59

clear fluid; like blood plasma; renewed continuously; filtrate of blood; supples nutrients and oxygen to lens and cornea

Front 60

scleral venous sinus

Back 60

large vessel a the corneoscleral junction

Front 61

lens

Back 61

thick, transparent, biconvex disc; changes shape to allow focusing of light on retina

Front 62

lens epithelium

Back 62

on anterior surface of lens

Front 63

lens fibers

Back 63

form most of the lens; contain folded proteins that make them transparent; new fibers are added continuously

Front 64

accommodation

Back 64

adjustability of lens that allows it to focus on nearby objects; lens is made rounder so it can focus on nearby objects; ciliary muscle contracts, releasing tension on ciliary zonule and lens is no longer stretched and becomes rounder

Front 65

auricle

Back 65

shell-shaped projection that surrounds opening of external acoustic meatus; elastic cartilage covered by skin

Front 66

external acoustic meatus

Back 66

short tube running medially from auricle to eardrum

Front 67

tympanic membrane

Back 67

thin translucent eardrum

Front 68

middle ear

Back 68

small air-filled space inside petrous part of temporal bone

Front 69

round window

Back 69

small hole in inferior medial wall of middle ear

Front 70

oval window

Back 70

small hole in superior medial wall of middle ear

Front 71

pharyngotympanic tube

Back 71

links middle ear to the pharynx; allows air pressure in middle ear to equalize with outside air pressure

Front 72

auditory ossicles

Back 72

three bones in tympanic cavity in middle ear; transmit vibrations of eardrum to fluid in inner ear

Front 73

malleus

Back 73

bone in middle ear shaped like a club with knob on top

Front 74

incus

Back 74

bone in middle ear shaped like a tooth

Front 75

stapes

Back 75

small bone in middle ear shaped like a stirrup

Front 76

tensor tympani and stapedius

Back 76

small skeletal muscles in middle ear; limit vibrations of ossicles and prevent damage to hearing receptos

Front 77

internal ear

Back 77

within the petrous part of the temporal bone; two divisions: bony labyrinth and membranous labyrinth

Front 78

bony labyrinth

Back 78

cavity in petrous bone that is made of system of twisting channels; three parts: semicircular canals, vestibule and cochlea

Front 79

membranous labyrinth

Back 79

series of membrane-walled sacs and ducts that fit within bony labyrinth; main parts: semicircular ducts, utricle and succule, cochlear duct; thin layer of ct lined by simple squamous epithelium

Front 80

endolymph

Back 80

clear fluid in membranous labyrinth

Front 81

perilymph

Back 81

clear fluid in bony labyrinth

Front 82

cochlea

Back 82

spiraling chamber in bony labyrinth; functions in hearing

Front 83

modiolus

Back 83

pillar of bone that cochlea spirals around

Front 84

cochlear nerve

Back 84

runs through core of modiolus; cochlear division of vestibulocochlear nerve

Front 85

cochlear duct

Back 85

part of the membranous labyrinth within cochlea; contains receptors for hearin

Front 86

vestibular membrane

Back 86

roof of cochlear duct, separating it from scala vestibuli

Front 87

basilar membrane

Back 87

floor of the cochlear duct

Front 88

spiral organ (of Corti)

Back 88

receptor epithelium for hearing; contain hair cells

Front 89

inner and outer hair cells

Back 89

receptor cells for hearing; stereocilia are tips of hairs at cell's apex; base of hair cells synapse with sensory fibers of the cochlear nerve

Front 90

spiral ganglion

Back 90

contain cell bodies of bipolar neurons that are sensory fibers of the cochlear nerve

Front 91

How do sound waves stimulate hair cells in spiral organ?

Back 91

1. Sound waves vibrate tympanic membrane
2. Auditory ossicles vibrate; pressure is amplified
3. pressure waves created by stapes pushing on oval window move through fluid in the scala vestibuli
4a. Sounds with frequencies below hearing travel through the helicotrema and do not excite hair cells
4b. sounds in the haring range to through the cochlear duct, vibrating the basilar membrane, but not tectorial membrane, so hair cells bend and release neurotransmitter that excites cochlear nerve fibers

Front 92

vestibule

Back 92

central cavity of bony labyrinth

Front 93

utricle

Back 93

egg shaped part of membranous labyrinth continuous with semicircular ducts

Front 94

sacule

Back 94

egg shaped part of membranous labyrinth continuous with cochlear duct

Front 95

macula of utricle and saccule

Back 95

spot of sensory epithelium; contain receptor cells that monitor position of head when head is still (static equillibrium); also monitor straight line changes in speed and direction of head movements (linear acceleration)

Front 96

vestibular nerve

Back 96

vestibular division of vestibulocochlear nerve; synapse with hair cells in macula

Front 97

otolithic membrane

Back 97

jellylike disc that contains heavy crystals of calcium carbonate (otoliths); in vestibule

Front 98

How does the maculae and otoliths contribute to sense of static equillibrium?

Back 98

macula of utricle has horizontal orientation in the ear
when one tilts the head, otolithic membrane pulls downward bending receptor hairs and stimulating vestibular nerve
macula of saccule has vertical orientation
otolithic membrane pulls downward on hair cells when the head is upright

Front 99

semicircular canals

Back 99

have receptors for rotational acceleration of head; 3 canals

Front 100

anterior and posterior semicircular canal

Back 100

lie in vertical plane at right angles

Front 101

lateral semicircular canal

Back 101

lies almost horizontally

Front 102

ampulla

Back 102

an expansion at one end of each semicircular canal

Front 103

semicircular duct

Back 103

part of membranous labyrinth in semicircular canal

Front 104

membranous ampulla

Back 104

swelling in semicircular duct that corresponds with ampulla in canal

Front 105

crista ampullaris

Back 105

small crest in each membranous ampulla; contain receptor cells that measure rotational acceleration; epithelium on apex containing receptor hair cells

Front 106

cupula

Back 106

tall jellylike mass that hair cells project through in crista ampullaris

Front 107

How does crista ampullaris respond to head rotation?

Back 107

head begins to rotate and endolymph in semicircular duct lags behind at first, pushing on cupula and bending the hairs; hairs bend and hair cells depolarize and change pattern of impulses carried by vestibular nerve fibers to brain