Senses- sight Flashcards
(22 cards)
The receptors for the sense of sight are ___________
Receptor is
Sight receptors are found in
in our eyes
Ø
:A specialized cell or tissue sensitive to a specific stimulus
the retina and they respond to light
Extrinsic eye muscles function
How many are there?
They are subdivided in ___ groups
to move your eyeball
6
2
Obliques
Recti
The eye wall can be divided into
3 layers
Outer layer/tunic: fibrous
Middle Layer/tunic: Vascular
Inner Layer/tunic: Neuronal
What is part of the outer tunic/ layer of they eye?
The bulgy transparent part
Sclera (whites of your eye)
Transparent portion, covering the pupil THE CORNEA
The middle layer is called?
How does it attach
It is highly vascular, why?
At the front of they eye, what does this middle later become?
There is a hole in this layer, at the front, what is it?
CHOROID
adheres to the sclera at the back
as it brings oxygen to the whole eyeball
The continuation of the choroid becomes the IRIS, the coloured portion of the eye
the PUPIL
What can the pupil be described as?
What can it do?
Name the parts of the middle layer of the eye
A diaphragm in a camera
Open and close and adjust according the amount of light it needs to let inside
choroid,
pupil,
iris
The inner layer of the eye is called
At the back of this layer is the
What is this responsible for?
Neuronal layer
retina
Seeing: contains the receptors
What types of photoreceptor cells are within the retina?
What do these receptor cells do?
Whaat layer is the retina known for?
RODS
Cones
Receive the message and send the information to the brain
The neuronal layer because the retina is connected to the optic nerve
What is the function of the optic nerve?
The part where the optic nerve connects to the retina is called
what does this area not contain
To carry the information into the brain.
blind spot
The blind spot doesn’t contain any receptor cells, no rods and cones
What is behind the pupil but not part of the tunics/ layers of the eye?
What is it responsible for?
How is it connected?
lens
Focussing
At the front of the eye, where the choroid meets the iris there are processes, CILLIARY BODY (muscles) PLUS LIGAMENTS
What is behind the lens?
What is it filled with?
What does it do?
What colour is it?
an area called the Posterior Chamber
Substance called vitreous humor
This jelly- like substance supports and protects, by cushioning the lens
Fills the space in the posterior chamber
Transparent
so when the light goes into the eye. the eye can pass through it, into the retina where the image lands
Infront of the iris, in-between the iris and the cornea (in the bulgy part) what is there?
What is it filled with?
Another chamber
the anterior chamber.
filled with water. Called aqueous humor
What surrounds the eyeball, in the socket? why?
When you look at something near, the lens…..
When you look at something far away, the lens…..
Fat for structural protection
looks bulgy and round
looks flatter
Rods are shaped like
Rods are responsible for?
Cones look like
Are responsible for?
Are there more rods or cones? why?
What other important cells are in the eye?
What do they do?
rectangular nail
see the shapes
arrow
seeing colours
Cones
Bipolar cells
ganglion cells
After the message is given to the rods and cones, it is passed to the bipolar, then the ganglion cells.
The ganglion cells all join to form a nerve. the optic nerve
Which cells would be best to see in a dark movie theatre?
What are the colour viewing cells?
Where are they found
Rods- they do not see colour as they react to very low light levels. Good for night vision
Cones
Mostly in the center of the retina
in an area called the macula lutea (provides the sharpest view)
Myopia
lens is Corrective lens:
(near-sighted):
Ø See near clearly, but not far
Ø Long eyeball, bulgy lens
Ø concave (diverging lens; bends light out)
Hyperopia
lens is:
Corrective lens:
far-sighted:
Ø See far clearly, but not near
Ø Short eyeball, flat lens
Ø Convex (converging lens;
bends light in)
myopia
(nearsightedness)
hyperopia
(farsightedness)
Ø
If the incoming light
focuses before it gets to
the back of the eye -
Ø
If the incoming light
does not focus by the time
it reaches the back of the
eye -
What do cataracts affect?
What causes it?
Can it be corrected?
What is the process?
Lens of the eye. Appears cloudy
Lens is made from specific proteins Crystallin.
Loss of elasticity of the lens followed by denature of crystallins making them less transparent
Yes with surgery
2 options
1 is to replace the lens with an artificial lens (most common)
What is a detached retina?
Often caused by…..
Separation of pigmented layer and photoreceptor layers of retina
Ø Photoreceptor cells have no access to blood vessels
Often caused by
trauma to the head
What is glaucoma?
if left untreated what can happen?
A build up of excessive pressure in the eye caused by a build- up of aqueous solution.
Eventually causes damage to the retina
Vision loss
