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1
Q

olfaction

A

sense of smell

2
Q

olfactory receptors

A

first order neurons of the olfactory pathway; each receptor is a bipolar neuron

3
Q

olfactory hairs

A

the parts of the olfactory receptors that respond to inhaled chemicals

4
Q

odorants

A

chemicals that have an odour and can therefore stimulate olfactory hairs

5
Q

supporting cells of olfactory system

A

column epithelial cells of the mucous membrane lining the nose; provide physical support, nourishment, electrical insulation for olfactory receptors and help detoxify chemicals that come in contact with the olfactory epithelium

6
Q

basal cells

A

stem cells located between the bases of the supporting cells; continually undergo cell division to produce new olfactory receptors (live for only a month before being replaced)

7
Q

olfactory glands or Bowman’s glands

A

produce mucous that is carried to the surface of the epithelium by ducts; moistens the surface of the olfactory epithelium and dissolves adroitness so that transduction can occur

8
Q

physiology of olfaction

A

A gen- erator potential (depolarization) develops and triggers one or more nerve impulses. In some cases, an odorant binds to an olfactory receptor protein in the plasma membrane of an olfactory hair (Figure 17.2). The olfactory receptor protein is coupled to a membrane protein called a G protein, which in turn activates the enzyme adenylate cyclase (see Section 18.4). The result is the following chain of events: production of cyclic adenosine monophosphate (cAMP) n opening of sodium ion (Na

9
Q

odour threshold

A

low threshold; only a few molecules of certain substances need to be present in air to be perceived as an odour

10
Q

adaptation to odours

A

decreasing sensitivity; occurs rapidly

11
Q

olfactory (I) nerves

A

40 bundles of axons collectively for left and right olfactory nerves; terminate in the brain in olfactory bulbs

12
Q

olfactory bulbs

A

paired masses of gray matter; ending of olfactory nerves

13
Q

olfactory tract

A

axons of olfactory bulb neurons extend posteriorly and form the olfactory tract

14
Q

gustation/ taste

A

a chemical sense; only 5 primary tastes can be distinguished : sour, sweet, bitter, salty and unami (meaty or savoury); less sensitive than olfaction; food can stimulate the olfactory system way more strongly than the gustatory system

15
Q

taste buds

A

oval body consisting of 3 kinds of epithelial cells: supporting cells, gustatory receptor cells and basal cells; amount declines with age;

16
Q

supporting cells of gustatory system

A

surround gustatory receptor cells in each taste bud

17
Q

taste pore

A

an opening in the taste bud where a long microvillus, a gustatory hair, projects from each gustatory receptor

18
Q

basal cell of gustatory system

A

stem cells found at the periphery of the taste bud near the connective tissue layer, produce supporting cells, which the develop into gustatory receptor cells

19
Q

papilla

A

elevations on the tongue where taste buds are found

20
Q

vallate (circumvallate) papillae

A

form an inverted V-shaped row at the back of the tongue; 12 large circular things

21
Q

fungiform papillae

A

mushroom shaped elevations scattered over the entire surface of the tongue that contain about 5 taste buds each

22
Q

foliate papillae

A

located in small trenches on the lateral margins of the tongue, but most of their taste buds degenerate in early childhood

23
Q

filiform papillae

A

pointed, threadlike structures contain tactile receptors but no taste buds; cover the entire surface of the tongue; increase friction between the tongue and food (makes it easier for the tongue to move food in the oral cavity)

24
Q

tastants

A

chemicals that stimulate gustatory receptor cells

25
Q

taste threshold

A

varies for each primary tastes; lowest for bitter taste (highest sensitivity);

26
Q

taste adaptation

A

Complete adaptation to a specific taste can occur in 1–5 minutes of continuous stimulation. Taste adaptation is due to changes that occur in the taste receptors, in olfactory receptors, and in neurons of the gustatory pathway in the CNS.

27
Q

eyelids/ palpebrae

A

shade the eye during sleep, protect eyes from excessive light and foreign objects and spread lubricating secretions over the eyeballs

28
Q

palpebral fissure

A

the space between the upper and lower eyelids that exposes the eyeball

29
Q

lacrimal caruncle

A

contains sebaceous (oil) glands and sudoriferous (sweat) glands

30
Q

tarsal glands or Meibomian glands

A

secrete fluid that helps keep the eyelids from adhering to eachother

31
Q

conjunctiva

A

thin, protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells that is supported by areolar connective tissue

32
Q

eyelashes

A

project from the border of each eyelid

33
Q

eyebrows

A

arch transversely above the upper eyelids; help protect the eyeballs from foreign objects, perspiration, and direct rays of the sun

34
Q

lacrimal aparatus

A

group of structures that produces and drains lacrimal fluid/tears

35
Q

lacrimal fluid

A

tears

36
Q

lacrimal glands

A

secrete lacrimal fluid; drains into lacrimal ducts

37
Q

excretory lacrimal ducts

A

empty tears onto the surface of the conjunctiva of the upper lid

38
Q

lacrimal canals

A

two ducts that tears pass into with lead into the lacrimal sac and then into the nasolacrimal duct

39
Q

nasolacrimal duct

A

duct that carries the lacrimal fluid into the nasal cavity just inferior to the inferior nasal concha

40
Q

lysozyme

A

a protective batericidal enzyme

41
Q

extrinsic eye muscles

A

extend from the walls of the bony orbit to the sclera (white) of the eye and are surrounded in the orbit by a significant quantity of periorbital fat; 6 extrinsic eye muscles: uperior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique

42
Q

wall of the eyeball (3 layers)

A

fibrous tunic, vascular tunic and retina

43
Q

fibrous tunic

A

superficial layer of the eyeball; consists of anterior cornea and posterior sclera

44
Q

cornea

A

transparent coat that covers the coloured iris; helps focus the light onto the retina (because it is curved)

45
Q

sclera

A

the “white” of the eye; layer of dense connective tissue made up mostly of collagen fibres and fibroblasts; covers the entire eyeball except the cornea; gives shape to the eyeball, makes it more rigid, protects its inner parts and serves as a site of attachment for the extrinsic eye muscles

46
Q

scleral venous sinus or canal of Schlemm

A

opening at the junction of the sclera and cornea

47
Q

vascular tunic/ uvea

A

middle layer of the eyeball; composed of 3 parts: choroid, ciliary body and iris

48
Q

choroid

A

highly vascularized; posterior portion of the vascular tunic, lines most of the internal surface of the sclera; blood vessels provide nutrients to the posterior surface of the retina; contains melanocytes that produce melanin (absorbs stray light rays, which prevents reflection and scattering of light within the eyeball)

49
Q

ciliary body

A

in the anterior portion of the vascular tunic, the choroid becomes the ciliary body

50
Q

ciliary processes

A

protrusions or folds on the internal surface of the ciliary body; contain blood capillaries that secrete aqueous humour

51
Q

zonular fibres (or suspensory ligaments)

A

extend from the ciliary process; attach to the lens; fibres consist of thin, hollow fibrils that resemble elastic connective tissue fibres

52
Q

ciliary muscle

A

circular band of smooth muscle; contraction or relaxation changes the tightness of the zonular fibres which alters the shape of the lens, (adapting it for near or far vision)

53
Q

iris

A

coloured portion of the eyeball; suspended between the cornea and the lends and is attached at its outer margin to the ciliary processes

54
Q

pupil

A

the hole in the centre of the iris

55
Q

circular muscles or sphincter pupillae

A

muscles causing the iris muscles to contract (constrict the size of the pupil)

56
Q

radial muscles or dilator pupillae

A

muscles causing the iris muscles to contract (dilate the pupils)

57
Q

retina

A

the third (inner) layer of the eyeball; lines the posterior three-quarters of the eyeball and is the beginning of the visual pathway

58
Q

optic disc

A

site where the optic (II) nerve exits the eyeball

59
Q

pigmented layer

A

sheet of melanin- containing epithelial cells located between the choroid and the neural part of the retina

60
Q

neural layer (3 major sublayers)

A

part of retina; multilayered outgrowth of the brain that processes visual data extensively before sending nerve impulses into axons that form the optic nerve; 3 layers: photoreceptor layer, bipolar cell layer, ganglion cell layer

61
Q

horizontal cells and amacrine cells

A

two of the types of cells present in the bipolar layer of the retina

62
Q

rods

A

allow us to see in dim light; do not provide colour vision

63
Q

cones

A

allow us to see brighter light; provide colour vision

64
Q

blind spot

A

optic disc; contains no rods or cones (we cannot see images that strike the blindspot)

65
Q

macula lutea

A

exact centre of the posterior portion of the retina, at the visual axis of the eye

66
Q

central fovea

A

depression in the centre of the macula lutea; contains only cones; area of highest visual acuity

67
Q

lens

A

within the cavity of the eyeball

68
Q

anterior cavity

A

the space anterior to the lens; consists of two chambers

69
Q

anterior chamber

A

lies between the cornea and the iris

70
Q

posterior chamber

A

lies behind the iris and in front of the zonular fibres and lens

71
Q

aqueous humour

A

transparent, watery fluid that nourishes the lens and cornea; fills both chambers of the anterior cavity

72
Q

vitreous chamber

A

lies between the lends and the retina

73
Q

vitreous body

A

transparent jellylike substance that holds the retina flush against the choroid, giving the retina an even surface for the reception of clear images

74
Q

intraocular pressure

A

the pressure in the eye; produced mainly by the aqueous humour and partly by the vitreous body

75
Q

refraction

A

bending of light

76
Q

accommodation

A

increase in curvature of the lens for near vision

77
Q

near point of vision

A

minimum distance from the eye that an object can be clearly focused with the maximum accommodation

78
Q

presbyopia

A

with aging, the lens loses elasticity and thus its ability to curve to focus on objects that are close

79
Q

emmetropic eye

A

the normal eye

80
Q

myopia

A

nearsightedness; when the eyeball is too long relative to the focusing power of the cornea and lens, or when the lens is thicker than normal, so an image converges in from of the retina

81
Q

hypermetropia or hyperopia

A

farsightedness; when the eyeball is too short relative to focusing power of the cornea and lens; or the lens is thinner than normal, so an image converges behind the retina; can see distant objects clearly but not close ones

82
Q

astigmatism

A

either the cornea or the lens has an irregular curvature; means hat parts of the image are out of focus and so vision is blurred or distorted

83
Q

constriction of the pupil

A

narrowing of the diameter of the hole through which light enters the eye due to the contraction of the circular muscles of the iris

84
Q

convergence

A

refers to this medial movement of the two eyeballs so that both are directed toward the object being viewed

85
Q

binocular vision

A

both eyes focus on only one set of objects

86
Q

photopigment

A

a coloured protein that undergoes structural changes when it absorbs light, in the outer segment of a photoreceptor

87
Q

rhodoposin

A

the single type of photopigment in rods

88
Q

cone photopigments

A

present in the retina, one in each of three three types of cones; colour vision comes from different colours of light selectively activating the different cone photopigments

89
Q

opsin

A

a glycoprotein contained inside all photopigments associated with vision

90
Q

retinal

A

a derivative of vitamin A contained inside all photopigments associated with vision

91
Q

bleaching and regeneration of photopigment

A

bleaching: the final product of trans-retinal completely separates from opsin and it looks colourless
regeneration: resynthesis of a photopigment; page 654 diagram

92
Q

light adaptation

A

when you emerge from dark surroundings into sunshine; your visual system adjusts in seconds to the brighter environment by decreasing its sensitivity

93
Q

dark adaptation

A

when you enter a darkened room; visual system adjusts by increasing sensitivity

94
Q

colour blindness

A

an inherited inability to distinguish between certain colours, result from the absence or deficiency of one of the three types of cones

95
Q

night blindness or nyctalopia

A

a deficiency and the resulting below normal amount of rhodopsin can cause an inability to see well at low light levels

96
Q

visual pathway

A

the axons of retinal ganglion cells provide output from the retina to the brain, exiting the eyeball as the optic (II) nerve.

97
Q

optic chiasm

A

a crossing point of the optic nerves; the axons within the optic (II) nerve pass through the optic chiasm

98
Q

optic tract

A

after passing through the optic chasm, the axons, now part of the optic tract, enter the brain

99
Q

optic radiations

A

project tot he primary visual areas in the occipital lobes of the cerebral cortex

100
Q

visual field

A

everything that can be seen by one eye

101
Q

binocular visual field

A

large region where the visual fields of two eyes overlap

102
Q

nasal (central) half and temporal (peripheral) half

A

visual field of each eye is divided into two regions: central half and temporal half; For each eye, light rays from an object in the nasal half of the visual field fall on the temporal half of the retina, and light rays from an object in the temporal half of the visual field fall on the nasal half of the retina. (page 656)

103
Q

hearing

A

the ability to perceive sounds

104
Q

anatomy of the ear; 3 regions

A

external ear, middle ear and internal ear

105
Q

external ear

A

collects sound waves and channels them inward; consists of the article, external auditory canal and eardrum

106
Q

auricle/pinna

A

a flap of elastic cartilage shaped like the flared need of a trumpet and covered by skin

107
Q

external auditory canal

A

a curved tube that lies in the temporal bone and lies to the eardrum

108
Q

ceruminous glands

A

specialized sweat glands contained within the external canal; secrete cerumen

109
Q

cerumen

A

earwax

110
Q

eardrum/ tympanic membrane

A

thin, semitransparent partition between the external auditory canal and middle ear; covered by epidermis and lined by simple cuboidal epithelium

111
Q

middle ear

A

small, air filled cavity in the petrous portion of the temporal bone that is lined by epithelium; separated from the external ear by the tympanic membrane and from the internal ear by a thin bony partition that contains two small membrane covered openings (oval window and the round window)

112
Q

auditory ossicles

A

3 smallest bones in the body; extends across the middle ear; connected by synovial joints; malleus, incus and stapes

113
Q

malleus

A

the handle; attaches to the internal surface of the tympanic membrane

114
Q

incus

A

middle bone ; articulates with the head of the stapes

115
Q

stapes

A

base/ footplate of the stapes fits into the oval window

116
Q

oval window

A

opening that the base/ footplate of the stapes fits into

117
Q

round window

A

opening directly below the oval window; enclosed by a membrane called the secondary tympanic membrane

118
Q

auditory tube or Eustachian tube

A

consists both bone and elastic cartilage, connects the middle ear the the nasopharynx (superior portion of the throat)

119
Q

internal (inner) ear/ labyrinth

A

consists of two main divisions: an outer bony labyrinth that encloses an inner membranous labyrinth

120
Q

bony labyrinth

A

series of cavities in the petrous portion of the temporal bone divided into 3 areas: semicircular canals, vestibule and cochlea

121
Q

perilymph

A

fluid (similar to cerebrospinal fluid) that surrounds the membranous labyrinth

122
Q

membranous labyrinth

A

a series of epithelial sacs and tubes inside the bony labyrinth that have the same general form as the bony labyrinth and house the receptors for hearing and equilibrium

123
Q

endolymph

A

fluid within the membranous labyrinth with an unusually high level of potassium ions which plays a role in generation of auditory signals

124
Q

vestibule

A

the oval central portion of the bony labyrinth

125
Q

utricle and saccule

A

two sacs contained in the membranous labyrinth in the vestibule

126
Q

semicircular canals

A

project superiorly and posteriorly from the vestibule;

127
Q

ampulla

A

a swollen enlargement in the semicircular canals

128
Q

semicircular ducts

A

the portions of the membranous labyrinth that lie inside the bony semicircular canals

129
Q

cochlea

A

a bony spiral canal that resembles a snail’s shell

130
Q

cochlear duct or scala media

A

continuation of the membranous labyrinth into the cochlea; filled with endolymph

131
Q

scala vestibuli

A

the channel above the cochlear duct; ends at the oval window

132
Q

scala tympani

A

channel below the cochlear duct; ends at the round window

133
Q

helicotrema

A

opening at the apex of the cochlea

134
Q

vestibular membrane

A

separates the cochlear duct from the scala vestibuli

135
Q

basilar membrane

A

separates the cochlear duct from the scala tympani

136
Q

spiral organ or organ of Corti

A

rests on the basilar membrane; coiled sheet of epithelial cells, including supporting cells and about 16,000 hair cells which are receptors for hearing

137
Q

hair cells

A

receptors for hearing

138
Q

tectorial membrane

A

a flexible gelatinous membrane that covers the hair cells of the spiral organ

139
Q

sound waves

A

alternating high and low pressure regions traveling int he same direction through some medium

140
Q

frequency

A

is it’s pitch; higher frequency = higher pitch

141
Q

decibels (dB)

A

unit that measures sound intensity

142
Q

static equilibrium

A

maintenance of the position of the body (mainly the head) relative to the force of gravity

143
Q

dynamic equilibrium

A

maintenance of the position of the body (mainly the head) in response to sudden movements such s rotational acceleration or deceleration

144
Q

vestibular apparatus

A

collectively, the receptor organs for equilibrium; the saccule, utricle and semicircular ducts

145
Q

otholithic membrane

A

rest on hair cells; thick, gelatinous, glycoprotein layer

146
Q

cupula

A

gelatinous material that covers the crista

147
Q

cataracts

A

cause of blindness; loss of transparency of the lends; lends becomes cloudy due to changes in the structure of the lends proteins

148
Q

glaucoma

A

most common cause of blindness in the USA; due to an abnormally high intraocular pressure as a result of a buildup of aqueous humour within the anterior cavity

149
Q

deafness

A

significant or total hearing loss

150
Q

conjunctivitis

A

pink eye; inflammation of the conjunctiva

151
Q

keratitis

A

an inflammation or infection of the cornea

152
Q

tinnitus

A

a ringing, roaring or clicking in the ears

153
Q

vertigo

A

a sensation of spinning or movement in which the world seems to revolve or the person seems to revolve in space