Chapter 17 Flashcards
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
taste threshold
varies for each primary tastes; lowest for bitter taste (highest sensitivity);
26
taste adaptation
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
eyelids/ palpebrae
shade the eye during sleep, protect eyes from excessive light and foreign objects and spread lubricating secretions over the eyeballs
28
palpebral fissure
the space between the upper and lower eyelids that exposes the eyeball
29
lacrimal caruncle
contains sebaceous (oil) glands and sudoriferous (sweat) glands
30
tarsal glands or Meibomian glands
secrete fluid that helps keep the eyelids from adhering to eachother
31
conjunctiva
thin, protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells that is supported by areolar connective tissue
32
eyelashes
project from the border of each eyelid
33
eyebrows
arch transversely above the upper eyelids; help protect the eyeballs from foreign objects, perspiration, and direct rays of the sun
34
lacrimal aparatus
group of structures that produces and drains lacrimal fluid/tears
35
lacrimal fluid
tears
36
lacrimal glands
secrete lacrimal fluid; drains into lacrimal ducts
37
excretory lacrimal ducts
empty tears onto the surface of the conjunctiva of the upper lid
38
lacrimal canals
two ducts that tears pass into with lead into the lacrimal sac and then into the nasolacrimal duct
39
nasolacrimal duct
duct that carries the lacrimal fluid into the nasal cavity just inferior to the inferior nasal concha
40
lysozyme
a protective batericidal enzyme
41
extrinsic eye muscles
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
wall of the eyeball (3 layers)
fibrous tunic, vascular tunic and retina
43
fibrous tunic
superficial layer of the eyeball; consists of anterior cornea and posterior sclera
44
cornea
transparent coat that covers the coloured iris; helps focus the light onto the retina (because it is curved)
45
sclera
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
scleral venous sinus or canal of Schlemm
opening at the junction of the sclera and cornea
47
vascular tunic/ uvea
middle layer of the eyeball; composed of 3 parts: choroid, ciliary body and iris
48
choroid
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
ciliary body
in the anterior portion of the vascular tunic, the choroid becomes the ciliary body
50
ciliary processes
protrusions or folds on the internal surface of the ciliary body; contain blood capillaries that secrete aqueous humour
51
zonular fibres (or suspensory ligaments)
extend from the ciliary process; attach to the lens; fibres consist of thin, hollow fibrils that resemble elastic connective tissue fibres
52
ciliary muscle
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
iris
coloured portion of the eyeball; suspended between the cornea and the lends and is attached at its outer margin to the ciliary processes
54
pupil
the hole in the centre of the iris
55
circular muscles or sphincter pupillae
muscles causing the iris muscles to contract (constrict the size of the pupil)
56
radial muscles or dilator pupillae
muscles causing the iris muscles to contract (dilate the pupils)
57
retina
the third (inner) layer of the eyeball; lines the posterior three-quarters of the eyeball and is the beginning of the visual pathway
58
optic disc
site where the optic (II) nerve exits the eyeball
59
pigmented layer
sheet of melanin- containing epithelial cells located between the choroid and the neural part of the retina
60
neural layer (3 major sublayers)
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
horizontal cells and amacrine cells
two of the types of cells present in the bipolar layer of the retina
62
rods
allow us to see in dim light; do not provide colour vision
63
cones
allow us to see brighter light; provide colour vision
64
blind spot
optic disc; contains no rods or cones (we cannot see images that strike the blindspot)
65
macula lutea
exact centre of the posterior portion of the retina, at the visual axis of the eye
66
central fovea
depression in the centre of the macula lutea; contains only cones; area of highest visual acuity
67
lens
within the cavity of the eyeball
68
anterior cavity
the space anterior to the lens; consists of two chambers
69
anterior chamber
lies between the cornea and the iris
70
posterior chamber
lies behind the iris and in front of the zonular fibres and lens
71
aqueous humour
transparent, watery fluid that nourishes the lens and cornea; fills both chambers of the anterior cavity
72
vitreous chamber
lies between the lends and the retina
73
vitreous body
transparent jellylike substance that holds the retina flush against the choroid, giving the retina an even surface for the reception of clear images
74
intraocular pressure
the pressure in the eye; produced mainly by the aqueous humour and partly by the vitreous body
75
refraction
bending of light
76
accommodation
increase in curvature of the lens for near vision
77
near point of vision
minimum distance from the eye that an object can be clearly focused with the maximum accommodation
78
presbyopia
with aging, the lens loses elasticity and thus its ability to curve to focus on objects that are close
79
emmetropic eye
the normal eye
80
myopia
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
hypermetropia or hyperopia
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
astigmatism
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
constriction of the pupil
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
convergence
refers to this medial movement of the two eyeballs so that both are directed toward the object being viewed
85
binocular vision
both eyes focus on only one set of objects
86
photopigment
a coloured protein that undergoes structural changes when it absorbs light, in the outer segment of a photoreceptor
87
rhodoposin
the single type of photopigment in rods
88
cone photopigments
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
opsin
a glycoprotein contained inside all photopigments associated with vision
90
retinal
a derivative of vitamin A contained inside all photopigments associated with vision
91
bleaching and regeneration of photopigment
bleaching: the final product of trans-retinal completely separates from opsin and it looks colourless
regeneration: resynthesis of a photopigment; page 654 diagram
92
light adaptation
when you emerge from dark surroundings into sunshine; your visual system adjusts in seconds to the brighter environment by decreasing its sensitivity
93
dark adaptation
when you enter a darkened room; visual system adjusts by increasing sensitivity
94
colour blindness
an inherited inability to distinguish between certain colours, result from the absence or deficiency of one of the three types of cones
95
night blindness or nyctalopia
a deficiency and the resulting below normal amount of rhodopsin can cause an inability to see well at low light levels
96
visual pathway
the axons of retinal ganglion cells provide output from the retina to the brain, exiting the eyeball as the optic (II) nerve.
97
optic chiasm
a crossing point of the optic nerves; the axons within the optic (II) nerve pass through the optic chiasm
98
optic tract
after passing through the optic chasm, the axons, now part of the optic tract, enter the brain
99
optic radiations
project tot he primary visual areas in the occipital lobes of the cerebral cortex
100
visual field
everything that can be seen by one eye
101
binocular visual field
large region where the visual fields of two eyes overlap
102
nasal (central) half and temporal (peripheral) half
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
hearing
the ability to perceive sounds
104
anatomy of the ear; 3 regions
external ear, middle ear and internal ear
105
external ear
collects sound waves and channels them inward; consists of the article, external auditory canal and eardrum
106
auricle/pinna
a flap of elastic cartilage shaped like the flared need of a trumpet and covered by skin
107
external auditory canal
a curved tube that lies in the temporal bone and lies to the eardrum
108
ceruminous glands
specialized sweat glands contained within the external canal; secrete cerumen
109
cerumen
earwax
110
eardrum/ tympanic membrane
thin, semitransparent partition between the external auditory canal and middle ear; covered by epidermis and lined by simple cuboidal epithelium
111
middle ear
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
auditory ossicles
3 smallest bones in the body; extends across the middle ear; connected by synovial joints; malleus, incus and stapes
113
malleus
the handle; attaches to the internal surface of the tympanic membrane
114
incus
middle bone ; articulates with the head of the stapes
115
stapes
base/ footplate of the stapes fits into the oval window
116
oval window
opening that the base/ footplate of the stapes fits into
117
round window
opening directly below the oval window; enclosed by a membrane called the secondary tympanic membrane
118
auditory tube or Eustachian tube
consists both bone and elastic cartilage, connects the middle ear the the nasopharynx (superior portion of the throat)
119
internal (inner) ear/ labyrinth
consists of two main divisions: an outer bony labyrinth that encloses an inner membranous labyrinth
120
bony labyrinth
series of cavities in the petrous portion of the temporal bone divided into 3 areas: semicircular canals, vestibule and cochlea
121
perilymph
fluid (similar to cerebrospinal fluid) that surrounds the membranous labyrinth
122
membranous labyrinth
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
endolymph
fluid within the membranous labyrinth with an unusually high level of potassium ions which plays a role in generation of auditory signals
124
vestibule
the oval central portion of the bony labyrinth
125
utricle and saccule
two sacs contained in the membranous labyrinth in the vestibule
126
semicircular canals
project superiorly and posteriorly from the vestibule;
127
ampulla
a swollen enlargement in the semicircular canals
128
semicircular ducts
the portions of the membranous labyrinth that lie inside the bony semicircular canals
129
cochlea
a bony spiral canal that resembles a snail's shell
130
cochlear duct or scala media
continuation of the membranous labyrinth into the cochlea; filled with endolymph
131
scala vestibuli
the channel above the cochlear duct; ends at the oval window
132
scala tympani
channel below the cochlear duct; ends at the round window
133
helicotrema
opening at the apex of the cochlea
134
vestibular membrane
separates the cochlear duct from the scala vestibuli
135
basilar membrane
separates the cochlear duct from the scala tympani
136
spiral organ or organ of Corti
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
hair cells
receptors for hearing
138
tectorial membrane
a flexible gelatinous membrane that covers the hair cells of the spiral organ
139
sound waves
alternating high and low pressure regions traveling int he same direction through some medium
140
frequency
is it's pitch; higher frequency = higher pitch
141
decibels (dB)
unit that measures sound intensity
142
static equilibrium
maintenance of the position of the body (mainly the head) relative to the force of gravity
143
dynamic equilibrium
maintenance of the position of the body (mainly the head) in response to sudden movements such s rotational acceleration or deceleration
144
vestibular apparatus
collectively, the receptor organs for equilibrium; the saccule, utricle and semicircular ducts
145
otholithic membrane
rest on hair cells; thick, gelatinous, glycoprotein layer
146
cupula
gelatinous material that covers the crista
147
cataracts
cause of blindness; loss of transparency of the lends; lends becomes cloudy due to changes in the structure of the lends proteins
148
glaucoma
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
deafness
significant or total hearing loss
150
conjunctivitis
pink eye; inflammation of the conjunctiva
151
keratitis
an inflammation or infection of the cornea
152
tinnitus
a ringing, roaring or clicking in the ears
153
vertigo
a sensation of spinning or movement in which the world seems to revolve or the person seems to revolve in space
