Special Senses (Intro and Vision) Flashcards
(111 cards)
1
Q
Type of receptors in sight
A
Photoreceptors
2
Q
Type of receptors in hearing
A
Mechanoreceptors
3
Q
Type of receptors in equilibrium
A
Mechanoreceptors
4
Q
Type of receptors in olfaction
A
Chemoreceptors
5
Q
Type of receptors in olfaction
A
Chemoreceptors
6
Q
Is touch a special sense?
A
No - it is a general sense
7
Q
Location of special senses?
A
Localised to the head - within specialised organs/structures
8
Q
What is dominant sense? What percentage?
A
Vision. 70% of all sensory input
9
Q
How is the eye protected
A
Cushion of fat
and Bony orbit
10
Q
What are 5 accessory eye structures?
A
Eyelids (palpebrae) Eyebrows Conjunctiva Lacrimal apparatus Extrinsic eye muscles
11
Q
What is the function of the palpebral?
A
Protect the eye anteriorly
12
Q
What is the opening which separates the eyelids?
A
Palperbae fissure
13
Q
Where do the eyelids meet?
A
At canthi:
Medial commissure
Lateral commissure
14
Q
What is the role of the lacrimal caruncle?
A
Contains sebaceous and sweat glands
Function: secretes oily secretion (for lubrication)
15
Q
What is within the upper eyelid? What is it’s role?
A
Tarsal plates
Tough connective tissue
Function: support the eyelids internally
16
Q
What is responsible for elevating the upper eyelids?
A
Levator palpebrae superioris
17
Q
What is the function of eyelashes?
A
Protect the eyelid via reflex response
18
Q
What are the glands between the eyelashes called, and what do they do?
A
Meibomian (tarsal) glands - produce lipid layer
Sebaceous glands
Sweat glands
Function: lubricate the eye
19
Q
What is the importance of lubrication to the eye?
A
Prevents abrasion
20
Q
What is the function of the eyebrows?
A
Shade the eye
Prevent perspiration running into eye
Facial expression
21
Q
What does the orbicularis occuli do to the eyebrows?
A
Depresses the eyebrows
22
Q
What does the corrugated muscle do to the eyebrows?
A
Moves eyebrows medially
23
Q
What muscles degrees the eyebrows, and move the eyebrows medially
A
Orbicularis oculi
Corrugator muscles
24
Q
What does the lacrimal apparatus consist of?
A
Lacrimal glands and ducts
25
What do lacrimal glands secrete? What do they contain?
```
Tears
Contains:
-mucus
-antibodies
-lysosomes
```
26
Explain the pathway of tears?
Enter the eye via the superolateral excretory ducts (from the lacrimal gland)
Exit the eye via the lacrimal puncture
Drain into the nasolacrimal duct
27
What are the three types of tears?
Basal tears
Tears from irritation
Tears from emotion
28
What is the conjunctiva? Function? Components?
Delicate transparent membrane
Function: lubricates and protects eye
Bulbar conjunctiva - covers white of eye
Palpebral conjunctiva - lines eyelid
29
Discuss the vascularity and nerves of the conjunctiva
Highly vascular - only see blood vessels when inflamed
| Lots of nerve endings - pain receptors (protect eye)
30
What holds contact lenses in place?
The conjunctival sac
31
What is conjunctivitis?
Inflammation of the conjunctiva
32
What does the lateral rectus do? Nerve?
```
Moves eye laterally
Abducens nerve (VI)
```
33
What does the medial rectus do? Nerve?
```
Move eye medially
Oculomotor nerve (III)
```
34
What does the superior rectus do? Nerve?
```
Move eye medially and superiorly
Oculomotor nerve (III)
```
35
What does the inferior rectus do? Nerve?
```
Move eye medially and inferiorly
Oculomotor nerve (III)
```
36
What does the inferior oblique do? Nerve?
```
Move eye laterally and superiorly
Oculomotor nerve (III)
```
37
What does the superior oblique do? Nerve?
```
Move eye laterally and inferiorly
Trochlea nerve (IV)
```
38
What muscles are used when looking at the left superior field of view?
Left eye: inferior oblique
| Right eye: superior rectus
39
What are the three layers of the eyeball, from inside to outside?
Sensory, vascular, fibrous
40
The lens separates the eyeball into ______ and _______ ______.
anterior and posterior segments
41
The _____ separates the eyeball into anterior and posterior segments.
lens
42
What makes up the fibrous layer? Clear/transparent/translucent/opaque etc
Sclera (posterior = opaque) and cornea (anterior = clear)
43
What is the role of the sclera?
Protects the eye
Anchors extrinsic eye muscles
Continuous with dura mater
44
What is the role of the cornea?
Major light bending apparatus
45
What is the structure of the cornea? Layers, pump, nerves.
Epithelium outside
Endothelium inside
Sodium pump --> maintains low water concentration --> no bacteria
Many pain receptors --> pain
46
What makes up the vascular layer?
Choroid (posterior) + ciliary body (more anterior) + iris (most anterior)
47
What is a feature of the choroid? What does it do?
Many blood vessels - nourish all layers
48
What are the features of the ciliary body?
Ciliary muscle and ciliary zonules
49
What changes the lens shape?
Ciliary muscles and ciliary zonules
50
What does contraction of ciliary muscle do to the lens?
```
Zonules become loose.
Lens rounds (close-up)
```
51
What does relaxation of ciliary muscle do to the lens?
```
Zonules become tight
Lens widens (distant)
```
52
What is the coloured part of the eye?
Iris
53
What is the function of the iris?
Regulates the amount of light which enters the eye?
54
What is the pupil?
Opening in the centre of the iris
55
What happens during pupil constriction?
Sphincter pupillae contracts (inner muscle)
Parasympathetic control
In bright light / close vision
56
What happens during pupil dilation?
Dilator pupillae
Sympathetic control - fight or flight
In dim light / distant vision
57
What is the sensory layer made up of?
Retina
58
What are the layers of the retina? What are their functions?
Pigmented epithelial layer (posterior)
Pigmented
Function: absorbs light (prevents scattering, stores Vit A, engulf dead photoreceptors)
Neural layer (anterior)
Clear
Has three layers: - photoreceptors, bipolar cells, ganglion cells (posterior to anterior)
59
What is the pathway of light in the eye?
Anterior to posterior
60
What is the pathway of signals in the eye?
Posterior to anterior
61
What is the optic disk?
Where the optic nerve leaves the eye - not photoreceptors - blind spot (brain fills it in with light)
62
What is the blood supply for the retina?
Outer 1/3 = from choroid
| Inner 2/3 = from central artery and vein
63
What does the central artery and vein supply?
Inner 2/3 of the retina
64
Are there more rods or cones?
More rods.
65
Are rods sensitive or not? Dim or bight light? Peripheral/close up vision? Colour/not
Very sensitive
Dim light
Peripheral vision
Not colour.
66
Are cones sensitive or not? Dim or bight light?
Not very sensitive
Bright light
Close-up, detailed vision
Allow colour perception
67
Do rods or cones allow colour perception?
Cones
68
Can rods summate GP to form an AP? Where do they converge to?
Yes - converge to bipolar cell
69
Can cones summate GP to form an AP? Where do they converge to?
No
70
What is the fovea centralis? Where is it?
Only cones.
| Lateral to blind spot
71
What is the macula lute? Where is it?
```
Mostly cones (some rods)
Surrounds fovea centralis
```
72
What happens as you move out from the fovea centralism (rods and cones)
Less cones, more rods
73
Vitreous humour is/is not replenished.
Not replenished. Formed in embryo.
74
Aqueous humour is/is not replenished.
Is replenished
75
Function of vitreous humour?
Transmits light
Supports posterior surface of lens
Holds neural retina firmly against pigmented layer
Contributes to intraocular pressure
Helps contract pulling force of extrinsic eye muscles
76
The anterior segment of the eye contains _________ humor? Produce where?
Aqueous. Produced by ciliary bodies
77
The posterior segment of the eye contains _________ humor? Produced where?
Vitreous. Produced in embyro - lasts a lifetime
78
The iris separates the ________ segment of the eye into ________ and _________ _________.
anterior, anterior, posterior, chambers
79
The ______ separates the anterior segment of the eye into ________ and _________ _________.
iris, anterior, posterior, chambers
80
Function of aqueous humour? Filters from where?
Supports, nourishes and removes wastes in the anterior segment of eye
Filters from capillaries of ciliary bodies --> posterior chamber.
Some flows through vitreous humour. Rest flows from posterior chamber to anterior chamber through pupil.
Then drains via scleral venous sinus
81
How does aqueous humour drain?
Out of the scleral venous sinus
82
What is glaucoma? How is it fixed?
Scleral venous sinus blocked due to increased intraocular pressure.
Requires surgical treatment
83
What does the ciliary body contain?
Ciliary processes and ciliary muscles
84
What is the shape of the lens? Opaque, translucent etc? Nutrients from where?
Biconvex
Transparent
Avascular - nourishment from aqueous humor
85
Lens fibres contain? Opaque, translucent etc?
No nuclei. Few organelles.
Transparent.
Contain crystalline = refracts light
86
Lens epithelium is the _______ surface and is made of ________ cells.
anterior, cuboidal
87
What happens to the lens with age?
Lens fibres become hardened (sclerosis)
| Lose elasticity - cannot as easily change shape and focus on detail (even when lens fibres contract)
88
What light do rods absorb?
The whole spectrum (therefore, do not discriminate between colour)
89
What light do cones absorb?
Blue cones - blue light
Red cones - red light
Green cones - green light
Therefore - colour perception
90
What is the pathway of light into the eye?
Moves through the:
- cornea
- aqueous humor
- through pupil to lens
- vitreous humor
- entire thickens of neural retina
- to reach photoreceptoes
91
Where is light refracted?
Three times:
When entering cornea
When entering lens
When leaving lens
92
What is accommodation?
Change of lens shape/curvature
93
Change of lens shape/curvature is called __________?
Accommodation
94
What happens to the lens for focussing on distant vision? Length? Refractive power / shape of lens? Nervous system? What happens to ciliary muscles
6m
Requires little adjustment
Sympathetic - fight or flight
Lower refractive power - flattened lens
Ciliary muscles relaxed - zonules tight - lens is flat
95
What happens to the lens for focussing on close-up vision? Distance? Refractive power / shape of lens? Nervous system? What happens to ciliary muscles
Less than 6m
Requires accommodation of the lens
Parasympathetic - rest and digest
Greater refractive power - rounder lens
Ciliary muscles contract - zonules lose - lens is rounder
96
What is emmetropic eye? Corrected by?
Normal
More than 6m - light focusses
Less than 6m - lens accommodates
No correction!
97
What is myopic eye? Corrected by?
Near sightedness
Eyeball too long for refractive power of lens
- distant objects focussed in front of retina (cannot see distant objects)
Corrected by: concave lenses (diverge light)
98
What is hyperopic eye? Corrected by?
Far sightedness
Eyeball too short for refractive power of lens
- distant objects focussed behind retina (can see as ciliary muscles contract to bring focal point forwards)
- close objects focussed too far behind behind retina (cannot be focussed onto retina - cannot see close-up objects)
Corrected by: convex lenses (converge light)
99
What is presbyopia?
As you age, lens becomes less elastic - cannot accommodate (similar to hyperopic eye)
100
Each photopigment contains ______ and _________.
Opsin and chromophore
101
What are the photopigments in rods and cones? Wavelengths?
```
Rods = rhodopsin (absorbs all wavelengths)
Cones = one for each type (absorbs specific wavelengths)
```
102
What does opsin do? What is it in rods and cones?
Filters light reaching chromophore (retinal in rods)
Different in each of 4 photopigments - allows retinal to absorb different wavelengths
103
What does chromophore do? What is it in rods and cones?
Light sensitive part of photopigments
Same in all 4 photopigments
Retinal in rods - a vitamin A derivative
104
Why is vitamin A important in the retina? Where is stored in the retina?
Stored in the pigmented epithelial layer
Important because retinal (in rods) is a vitamin A derivative
105
How many rods and cones are there?
100 million rods
| 3 million cones
106
Regneration in rods is _________. Takes ______.
Slow. 5 minutes
107
Regneration in cones is _________. Takes ______.
Fast. 90 seconds
108
True or false? A second messenger system occurs in photoreceptors.
True.
109
What does the second messenger system in photoreceptors do?
Amplifies responses!
110
The bipolar cell is disinhibited in the dark/light?
Light
111
An AP is generated in the dark/light?
Light
