Retinal Physiology Flashcards
(42 cards)
which three layers make the eye tissue? [3]
- outer layer: [2] (front and back?)
- middle layer: [1]
- inner laye: [1]
which three layers make the eye tissue? [3]
- outer layer: sclera (back); cornea (front)
- middle layer: uvea
- inner laye: retina
which of the following is the iris?
A
B
C
D
E
F
which of the following is the iris?
A
B
C
D
E
F
which of the following is the uvea?
A
B
C
D
E
F
which of the following is the uvea?
A
B
C
D
E
F
which of the following is the choroid?
A
B
C
D
E
F
which of the following is the choroid?
A
B
C
D
E
F
which of the following is the ciliary body?
A
B
C
D
E
F
which of the following is the ciliary body?
A
B
C
D
E
F
which of the following is the retina?
A
B
C
D
E
F
which of the following is the retina?
A
B
C
D
E
F
which of the following is the cornea?
A
B
C
D
E
F
which of the following is the cornea?
A
B
C
D
E
F
which part of the eye is the light sensing organ?
choroid
uvea
retina
sclera
iris
which part of the eye is the light sensing organ?
choroid
uvea
retina
sclera
iris
what is the name for the clear bulging surface in front of the eye? [1]
where does it recieve its nutrition from? [1]
whats the nerve supply like? [1]
what is the name for the clear bulging surface in front of the eye? [1]
cornea
where does it recieve its nutrition from? [1]
aqueous humour diffusion (its avasucular) BUT: richly supplied with nerve fibres
function? [2]
the main focussing surface of the eye: where the refractive index of the medium changes from air to transparent tissue !
what keeps the cornea’s shape? [1]
what keeps the cornea’s shape? [1]
intraocular pressure
what is the name for the white of the eye? [1]
what is the name for the pigmented bit of eye? [1]
what is the name for the white of the eye? [1]
sclera (although interior: brown & grooved)
what is the name for the pigmented bit of eye? [1]
iris
what is the conjunctiva? [1]
what type of cells make up the conjuctiva? [1]
function? [1]
what is the conjunctiva? [1]
layer
what type of cells make up the conjuctiva? [1]
stratified columnar epithelium; goblet cells
function? [2]
mucous secreted: mixes with tears to make more viscous
covers sclera & inside of eyelids
which part of the eye contrains pigment epithelial cells which prevent light scattering and reflection & sits inbetween the sclera and the retina?
iris
choroid
cornea
ciliary body
lens
which part of the eye contrains pigment epithelial cells which prevent light scattering and reflection & sits inbetween the sclera and the retina?
iris
choroid
cornea
ciliary body
lens
which part of the eye contains smooth muscle bundles which shapes the lens?
iris
choroid
cornea
ciliary body
lens
which part of the eye contains smooth muscle bundles which shapes the lens?
iris
choroid
cornea
ciliary body
lens
what is the role of the lens? [1]
how is the shape of the lens changed? [1]
what shape is the lens for:
a) close images?
b) distant images?
what is the role of the lens? [1]
- allows eye to focus on objects at various distances
how is the shape of the lens changed? [1]
- ciliary muscles contract / relax
a) close images: bulges
b) distant images: flat
where are the interneurons and ganglion cells which make up the optic nerve found in the eye? [1]
where are the interneurons and ganglion cells which make up the optic nerve found in the eye? [1]
retina
what is the fovea? [1]
what is the fovea? [1]
centre of the retina: where visual acuity (sensitivty) is highest
what is the blind spot? [1]
blind spot: place where visual axons leave the eye to form the optic nerve, so there are no photoreceptors here
what are the two types of photoreceptors? [2]
which of ^ do you only find in the fovea? [1]
which of ^ are more active in dark? [1]
what are the two types of photoreceptors? [2]
rods & cones (red, blue, green)
which of ^ do you only find in the fovea? [1]
cones
which of ^ are more active in dark? [1]
rods
describe the structre of rods & cones
outer segment: **photoreceptive part
i) rods contain photopigment called rhodopsin
ii) cones contain photopigment called cone opsins**
* *occur in stacked plates**
inner segment: cell body (& mito)
why are rods & cones have stacked free floating discs? [1]
why do eyes require high amounts of oxygen? [1]
why are rods & cones have stacked free floating discs? [1]
maximises the chance of a photon interacting with a molecule of photopigment
why do eyes require high amounts of oxygen? [1]
one of most metabolically active cells in the body
what happens to photoreceptors in the dark? [2]
what happens to photoreceptors in the light? [1]
what happens to photoreceptors in the dark? [1]
constant inward leak of sodium in outerpart of the receptor: keeps the cell depolarised. causes the release of glutamate from its synaptic ending
what happens to photoreceptors in the light? [1]
light hyperpolarises the tonic glutamate release
how does photorecption in rods occur? [3]
- absorbtion of light causes a confirmational change in shape of rhodopsin
- changed rhodopsin then acts via a G-protein to reduced the level of cyclic GMP in the rod
- reduced cyclin GMP: closes sodium channel, cell can repolarise & stop release of glutamate
how does photoreception in cones occur? VIA WHAT?
- contain opsins that absorb light at different wavelengths
- classes of opsins react to different ranges of light frequency: give **colour perception
signal transduction pathway v similar in rods & cones
BOTH DARK DETECTORS**
