Senses of Vision, Smell, Taste Flashcards
1
Q
conjunctiva
A
prevents foreign obj from entering post portion of eye
- layer over sclera, 2 parts
2
Q
palpebral portion of conjunctiva
A
mucous membrane that forms inner lining of eyelid
3
Q
bulbar portion of the conjunctiva
A
lines the white of the eye
4
Q
lacrimal caruncle
A
pink mound
contains modified oil and sweat glands
5
Q
flow of tears
A
lacrimal gland > lacrimal ducts > surface of eyeball > puncta > superior/inferior lacrimal canaliculi > lacrimal sac > nasolacrimal duct > nasal cavity
6
Q
extrinsic muscles of the eye
A
4 rectus (sup, inf, lat, medial) 2 oblique (sup and inf)
7
Q
rectus muscles
A
- attach to anterior portion of sclera and extend to post portion of the eye orbit where they attach to bone
- responsible for up, down, L, R movements of eye
8
Q
superior oblique muscle
A
- rotates eye medially and inferiorly
- runs through trochlea which acts as a pulley
9
Q
inferior oblique muscle
A
- rotates eye laterally and superiorly
10
Q
3 coats/tunics of the eye
A
- fibrous tunic
- vascular tunic
- retina
11
Q
fibrous tunic
A
outermost layer
white of the eye
made up of sclera (post) and cornea (ant.)
12
Q
sclera
A
- posterior part of the eye
- fibrous CT layer
- provides shape, protection, attachment to muscles
13
Q
cornea
A
- continuous w the sclera
- anterior portion of eye
- helps focus light
- avascular, gets some O2 from the air
14
Q
vascular tunic
A
contains melanin
composed of choroid (post) ciliary body and iris (ant)
15
Q
choroid
A
blood supply
black bc of melanin
16
Q
ciliary body
A
smooth muscles that change the shape of the lens
17
Q
iris
A
contains muscles that change the diameter of the pupil
18
Q
melanin
A
a pigment that makes the inner surface of the eye appear black and reduces light from reflecting around the inner surface of the eye
- also increases sharpness of vision
19
Q
pathway of light
A
enters through cornea > aqueous humor (ant cavity) > lens > vitreous body > retina (region of macula lutea and fovea centralis)
20
Q
lens
A
only solid tissue in the body that is transparent:
this is bc it begins a self destruct program that starts the breakdown of cells and stops it right before the cell dies
– lens cells exist w/o organelles or internal structures, allowing it to be completely clear
21
Q
anterior cavity
A
contains aqueous humor
22
Q
aqueous humor
A
- helps maintain interocular pressure & shape of eye
- provides nutrients & O2 for cornea and lens bc they are avascular
- helps w refraction of light
- once produced, it circulates through 2 chambers and is then reabsorbed into sinuses at the edge of the cornea
23
Q
zonular fibres
A
pull on lens, controlled by ciliary muscles
24
Q
vitreous humor
A
jelly like
- helps keep shape of eye
- holds retina layer flat against cornea and allows clear vision
25
ciliary body
how about the outer and inner muscles?
made up of ciliary muscles & attached to zonular fibres by ciliary processes
outer muscles: oriented in radial direction, stretch lens outward
inner muscles: oriented in circular manner, squish lens inward and out sort of
26
iris
controls size of pupil based on autonomic reflexes
27
sphincter pupillae
cause pupil to constrict as the circular muscles contract
28
dilator pupillae
causes pupil to dilate as radial muscles of iris contract
29
components of the retina
fovea centralis
macular lutea
optic disc
30
fovea centralis
contains only cones
| - is a small depression in the macular region
31
macula
contains more codes than rods
32
optic disc
where nerve and blood supply enter the eye
therefore we have a blind spot here
brain just fills in the blank though w visual info around it
33
light enters retinal layer in what direction
| action potential propagates in what direction
light: towards the retinal layer
AP: propagates back out, i guess
34
3 parts of neural layer that signals travel through before creating AP
- photoreceptor cell layer
- bipolar cell layer
- ganglion cell layer
35
3 events to bring an image to focus
1. Accommodation
2. Pupil constriction
3. Convergence
36
accommodation
ciliary muscles contract, lens becomes mores spherical, greater light refraction, focused obj
37
pupil constriction
depth of focus:
| pupil diameter small means a greater depth of focus
38
convergence
as an obj moves closer, eyes rotate medially to pick up light rays (this is made possible by our binocular vision)
39
what happens in the eye, how are light rays focused w regards to DISTANT vision
- receive nearly parallel rays from the object
- ciliary muscles are relaxed, tension in suspensory ligaments are high
thus, the lens is flattened, diameter is wide
40
what happens in the eye and how are light rays focused w regards to NEAR vision
- receive divergent rays from object
- ciliary muscles contract and suspensory ligaments relax
lens is thickened when ciliary ring gets smaller
41
what type of neurons are present in photoreceptors?
bipolar neurons
42
rods
- non colour vision
- low light
Rhodopsin: retinal and opsin, a photosensitive pigment
43
cones
colour vision
requires high light
cone photopigments : photopsin
- specialized as retinal and red, blue or green opsin
44
at rest, is a photoreceptor cell hyperpolarized or depolarized?
depolarized
45
generation of AP in the eye
yeah thats a good question lol
46
proprioception
body gathers info about muscles, joints to coordinate muscle movements
47
types of sensory receptors
```
mechanoreceptors
chemoreceptors
thermoreceptors
photoreceptors
nocioreceptors
```
48
mechanoreceptors
- compression, bending, stretching of cells
- touch, pressure, proprioception, hearing, balance
ex. mechanically gated ion channels
49
chemoreceptors
- chemicals bind to receptors on cell membrane
| - used for smell and taste
50
how are chemoreceptors differ from ligand gated ion channels?
in the chemoreceptors, when a chemical binds to the protein on the membrane, it triggers a signalling cascade inside the cell and then the channel opens
-- more steps than ligand gated
51
thermoreceptors
respond to changes in temp
| - not used in special senses
52
photoreceptors
respond to light
| vision: unique to retinal layer of eye
53
nocioreceptors
- extreme mechanical, chemical or thermal stimuli
| pain sensation: threshold is much higher, triggers when presented w extreme stimulus
54
concha
ridges that makes air turbulent as it enters naris
| - this causes the air to come in contact w mucus membranes of the nose, removes any debris, dissolves odorants too
55
structure of olfactory receptor cells
bipolar neuron
| dendrite end is highly specialized, and have cilia (called olfactory hairs)
56
odorants
- chemicals that cause smell
- not specific to receptors
- bind to odorant receptors on olfactory hairs
57
olfactory gland
- produces mucus that covers olfactory hairs
| - mucus dissolves odorants so that they can bind onto receptors on the olfactory hairs and cause a depolarization
58
basal cells
stem cells that can boils other cells of their layer such as supporting cells
- important for regeneration (every 2 months)
59
supporting cells
hold receptor cells in place
60
receptor cells tend to bind to molecules of __
similar size, shape and chemical composition
| - each odorant triggers a similar pathway of receptors
61
(olfactory) action potentials terminate where
- olfactory tract goes to temporal lobe
1. primary olfactory area: conscious perception of smell
2. medial olfactory area: visceral and emotional response to smell
62
adaptation to smell can occur 2 ways:
- so many odorant molecules are there that the chemoreceptors are saturated
OR
- once brain gets a signal it sends a signal back out to the olfactory bulb to block the synapse from sending the same signal again
63
primary classes of odors
```
camphoraceous
floral
musky
pepperminty
etheral (fruit)
pungent
putrid
```
64
papillae
epithelial project8ions on the tongue
65
vallate papillae
- V shaped kind of ridges (8-10)
- large in size
- ant 2/3 and post 1/3 of tongue
- have taste buds
66
filiform papillae
- look like fire
- most abundant
- NO tastebuds, main purpose is to create rough surface on superior portion of tongue
67
foliate papillae
- leaf shaped - nasty looking things on sides of tongue
| - taste buds start to degenerate after childhood
68
fungiform papillae
- mushroom shaped
- irregularly scattered on superior surface of the tongue
- have taste buds
69
taste bud
- specialized epithelial cell
- surrounded by stratified squamous epithelium
- sort of sandwiched in portions of papillae
70
receptor types for taste buds
```
5 types for 5 tastes:
sweet
salty
umami (savoury)
bitter
sour
```
71
gustatory receptor cells
- contain gustatory hairs where depolarization occurs
- the whole cell depolarizes (no axon, no AP)
- if graded potential gets large enough then it triggers Ca2+ channels to open
72
specialized dendrite region on taste buds
microvilli where chemoreceptors are located in the taste pore
73
tastants
chemicals dissolved in saliva
| - cause gustatory receptor cells to depolarize
74
adaptation to tastes
occurs when taste receptors are saturated
75
neuronal pathways for taste
```
gustatory receptor cells send NT to
cranial nerves VII, IX, X
medulla oblongata
thalamus
primary gustatory cortex
```
