Chapter 9 Flashcards
The Electomagnetic spectrum
Gammarays
X rays
UV Rays
Visible Light
Infrared Radiation
Microwaves
Radiowaves
pathway for vision
Vision starts in enviroment
light energy becomes electromagnetic energy going into eyes
What kind of energy can go into the eyes
electromagnetic energy
Which wavelengths are humans sensitive to
400 nm - 700 mn
Longer the wavelength the _______ dangerous it is to humans
less
Shorter wavelenghts are more _________ to humans
Dangerous
Clear outer covering protects the eye from dust
Cornea
Opening in eye that allows light in
Restricts how much light comes in the eye
Pupil
The white part of the eye is called ______ and it is in the ________
Scalara ; Iris
This part of the eye changes its shape to focus light on retina
Lens
Which part of the eye projects the light to retina
Lens
The lining at the back of the eye, and has neurons in it is called ____________
Retina
Middle of a visual field is projected in the ___________ and it is the part of the __________
Fovea , Retina
The image processed in the retina and in the brain is _______________
Upside down
________ has muscles that allows ________ to dilate or constrict
Iris ; pupil
When do pupils dilate
Expand
Allows for more light to come in
Example: When being in a dim room
When do pupils constrict
Gets smaller
Bright room
Allows less light to come in
Myopia
Object gets fuzzy as object gets far away
Nearsightedness
Hyperopia
Object hets fuzzy when closer
Far sightedness
Prebyopia
Version of hyperopia
When reading a book put book far away
Treated with reading classes
Too close cannot see propoerly
What is the main function of the retina
Retina converts light energy to neural energy
Rods are ______
Long
Cones are _______
Short
What is the role of receptors
They want to send signals to ganglion cells
Pathway of eye signalling
Receptors - Bipolar cells - Ganglion cells
Which receptors respond to light
Rods
Cones
What do bipolar cells do
take action potentials from receptors and send them to ganglion cells
What do Horizontal cells do?
Allows signals between receptors (cones and rods) and allow one receptor to affect another
What do Amarine cells do?
Allows signalling between Ganglion cells
Are there more rods or cones in the retina
Rods
Where are Rods located
In the periphery
Fovea has no _______
Rods
Two main functions of Rods
- We rely on rods in dim light conditions
- Responsive to motion
Where are cones in the eye
Everywhere
High density of cones are in the __________
Fovea
3 main functions of cones
- The fovea only has cones which allows of high detailed vision
- Allows us to see colour in the visual field
- Allows us to see in normal conditions
________ allows us to see in normal lighting conditions
Cones
What if we had only rods and no cones
We cannot see colour
Short Wavelength cones
Responding to light in the lower end of the spectrum
Blue
M cones
Middle part of the spectrum : Green
L cones
High part of the spectrum : Red
Scotropic conditions
Night conditions
Rod dependant
Phototrpic conditions
Light / Bright conditions
Cones dependent
Which colour and wavelength is dominant in scotropic conditions
Rod dependant
LW
Blue
Which colour is more bright in Phototropic conditions
Yellow
Purkinjee shift
Shift from - Cone vision - Rod visiom
Shift from Phototropic conditions - scotropic conditions
During day
Receptor:
Condition:
Colour:
Wavelength:
Cones
Photopic
Yellow
Medium to high
During Night
Receptor:
Condition:
Colour:
Wavelength:
Rods
Scotopic
Blue
Low
Two types of Ganglion cells
- Magnocellular (M cells)
- Parvocellular (P cells)
M cells
Signals from rods
P cells
Signals for cones through bipolar cells
Main pathway for vision
Geniculostriate pathway
Geniculostriate pathway
- EYE to LGN which is in the thalamus
- LGN to visual cortex
EYE to LGN is a _____ way signal
One
LGN to VC is a ____ way singal
Two
Retinotropic map
Constructed so the LGN can organize signals
Each part of the retina has its own corresponding area in the LGN
How many layers are in the LGN
6 Layers
Layer 1 and 2 are reserved for
M cells
Rods
Dim lighting
Motion
Scotopic
Less light enviroments
Pupils dilate
Short wavelengths
Blue
Layer 3 to 6 are reserved for
P cells
Cones
Normal lighting
Colour
Stationary objects
Pupils constrict
Medium - Long wavelengths
Fovea
Yellow
Tectopulvinar pathway
Visual signals travelling to superior colliculus in the midbrain
Tectopulvinar pathway is involved in _________
Reflexive eye movements
Unconcious
Retinohypothalamic pathway is only used by ________ cells getting signals from__________
M
Rods
Retinohypothalamic pathway
Retina - Hypothalamus
Retina - SCN - pineal gland releases mealtonin
Regulates sleep wake cycle
There is more area in the visual cortex to process _________
Fovea
Which cones do we have more of
Long and medium wavelength
Dichromacy
We dont have long WL cones
Cannot see red
More common i men