Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
65 Cards in this Set
- Front
- Back
|
What is scoptopic vision?
|
vision for dim illumination
|
|
|
Are rods or cones more active in scotopic vision?
|
Rods
|
|
|
What do rods detect in scotopic vision?
|
gross form and movement
|
|
|
Explain the sensitivity of rods?
|
extremely sensitive - a rod can be excited by a single photon
|
|
|
What do rod bipolars directly synapse with?
|
Amarines
|
|
|
What do rod bipolars not directly synapse with?
|
ganglion cell
|
|
|
Explain the 4 neuron chain of scotopic vision?
|
1) 75,000 rods
2) 5,000 rod bipolars 3) 250 AII 4) single ganglion |
|
|
The information from many rods will converge to how many ganglion cells?
|
one
|
|
|
Describe photopic vision?
|
vision in bright light
|
|
|
What do cones detect?
|
color and detail
|
|
|
Why does color vision occur?
|
different cones are activated by different wavelengths
|
|
|
What wavelengths activate cone opsins?
|
Red
Blue Green |
|
|
What do L cones respond to?
|
long wavelengths (red)
|
|
|
What do M cones respond to?
|
Medium wavelengths (green)
|
|
|
What do S cones respond to?
|
short wavelengths (blue)
|
|
|
How many bipolars can each cone pedicle contact?
|
10-15
|
|
|
What is the 3 neuron chain for scotopic vision?
|
1) 9 cones
2) 3 bipolars 3) single ganglion cell |
|
|
Why is there a greater convergence of rods onto bipolars than of cones?
|
there are way more rods (16:1)
|
|
|
Can a ganglion cell carry information from either rods or cones?
|
yes
|
|
|
How many cones are in the human retina?
|
4-5 million
|
|
|
How many rods are in the human retina?
|
80-100 million
|
|
|
How many ganglion are in the human retina?
|
1 million
|
|
|
At rest, describe the activity of a neuron?
|
rest = charged state
inside = negative |
|
|
At rest, describe the activity of a neuron?
|
rest = charged state
inside = negative |
|
|
What is the normal resting potental across a cell membrane and how is it maintianed?
|
-65mv
- maintained by Na/K flow |
|
|
What happens when a neuron is activated?
|
Na channels open
|
|
|
What happens when Na channels open?
|
inside gets less negative = depoloarization
|
|
|
When do neurons release NT?
|
when they are depolarized
|
|
|
What is an ERG?
|
Electroretinogram
measures photoreceptor-bipoloar synaptic current |
|
|
What is an electro-oculogram?
|
measures activity across the RPE
|
|
|
How are cells named on or off?
|
by light situation when the cell is depolarized
|
|
|
Are photoreceptors on or off cells?
|
Off
they depolorize to light off |
|
|
What do photorecptors when the light is on?
|
hyperpolarize
|
|
|
How to photoreceptors shift toward darkness?
|
1) depolarize
2) increased release of NT |
|
|
Does dark increase or decrease the release of NT?
|
increase
|
|
|
How do photoreceptors shift toward light?
|
1) hyperpolarize
2) decreased release of NT |
|
|
Does light increase or decrease release of NT?
|
decreases
|
|
|
What are the NT in the retina?
|
1) Glutatmate
2) Glycine 3) Acetycholine 4) Dopamine 5) GABA 6) Taurine |
|
|
What is the photoreceptor NT?
|
Glutamate
|
|
|
Where are receptors for gluatamte found?
|
1) Horizontals
2) bipolars 3) ganglion cells |
|
|
What type of cells tend to take up glutatmate, like a sink?
|
Muller cells
|
|
|
What allows the transmission of an electrical current without NT?
|
Gap junctions
|
|
|
Describe what cells gap junctions transmit electric current between?
|
cone to rod
cone to cone horizontal to horizontal |
|
|
What do bipolar cells response to?
|
redution of NT by hyperpol or depol
|
|
|
Bipolars that hyperpol to light are _____ cells?
|
Off
|
|
|
Bipolars the depol to light are _____ cells?
|
On
|
|
|
Photoceptor and bipolar's response is different how compared to ganglions?
|
photo and bipol = graded
ganglion = all or none |
|
|
On bipolars are what type of receptors?
|
metabotropic
|
|
|
Off bipolars are what type of receptors?
|
ionotropic
|
|
|
What is the receptive field?
|
points in the visual field where light elicits a change
|
|
|
What is the receptive field of a bipolar cell?
|
the portion of photoreceptors taht influence the bipolar cells
|
|
|
What is the receptive field of a bipolar cell due to?
|
the influence of horizontal cells (sum signal)
|
|
|
What is the receptive field of a ganglion cell?
|
the bipolar cels that influence the glangion cell (thus the photoreceptors that influence the bipolars)
|
|
|
Why can the number of influenced bipolar cells be greater than it's number of dendrites?
|
horizontal cells
|
|
|
What shape is a ganglion receptive field?
|
cicular
|
|
|
Describe what happens with light hits ON center cells?
|
1) hyperpolarization decreased GLU
2) depol 3) increases release of GLU 4) signals ganglion cell |
|
|
Describe what happens when light hits an OFF center cells?
|
1)inhibitory message = center turned off
2) ganglion is not signaled |
|
|
What is AII?
|
one of the first amarcines to be studied
|
|
|
What does AII do?
|
1) gets input for rod bipolars
2) inhibits action on OFF cone bipolars (chemical) 3) activates ON cone bipolars (electrical) 4) releases GLY or GABA |
|
|
What does A17 release?
|
GABA
|
|
|
What do ganglion cells respond with?
|
action potential
|
|
|
What % of ganglion signals go to the LGN? Where does the rest go?
|
90% to LGN
10% to Sup. collic, Pretectal nuc or Hypothal |
|
|
What is melanopsin?
|
has a role in melatonin release
|
|
|
When does the production/secretion of melatonin increase?
|
increase at night
(decrease during day) |
|
|
If a blind person has a functional inner retina, are they likely to experience sleep problems?
|
No
|
