Lecture 1/4 Flashcards
rods are ___ microns in length
100 microns
are rods shorter or longer than cones?
rods are longer than cones
example of the “funnel” ratio in the neural connections of the rods
10 rods: 5 bipolar : 1 ganglion
funnel shape arrangement of the rod wiring has what effects?
- decreased discrimination
- increased sensitivity
outer segment of photoreceptor is ___ microns in length
25 microns in length
about 1/4 the total length
photopigment in rod outer segment is:
rhodopsin
rhodopsin is coated on discs which are piled up in the outer segment. how many discs are there?
700-1000 discs piled up
the function of the inner segment of the photoreceptors is:
for metabolism
describe the connection between the inner and outer segment of the photoreceptors
connected by a cilium, which is a small slender tube (packed with microtubules)
the inner segment is made up of what 2 components?
- ellipsoid
- myoid
what does the ellipsoid of the inner segment contain?
high concentration of mitochondria (for energy)
what does the myoid of the inner segment contain?
vesicles containing endoplasmic reticulum, golgi apparatus, and ribosomes
what is the purpose of the outer conducting fiber?
connects inner segment to the cell body
nucleus of the rod is ___ microns
5 microns
which is smaller- the nucleus of the rod or cone?
the nucleus of the rod is smaller
which is farther away from the ELM- the nucleus of the rod or nucleus of the cone?
the nucleus of the rod is farther away from the ELM
purpose of the inner conducting fiber:
from the cell body to the synapse that ends in a foot plate
foot plate in the rods is called _____
Spherule
the cone is ___ microns in length
65-75 microns in length
about how many rods are in the retina?
~ 120 million
about how many cones are in the retina?
~ 6-7 million
cone neural connection arrangement in the macula is:
1 cone: 1 bipolar: 1 ganglion
the 1:1:1 ratio arrangement in the macula has what effects?
- increased discrimination
- decreased sensitivity
is the outer segment of the cone shorter or longer than in rods?
the outer segment is shorter in cones
is the inner segment more plump in the rods or the cones?
it is more plump in cones
why is the inner segment more plump in the cones?
it has 4x the amount of mitochondria
do the cones contain an outer conducting fiber?
no
*except in the fovea
is the nucleus of the cell body larger in cones or rods?
cell body nucleus is larger in cones
foot plate of the inner conducting fiber is called _____ in the cones
pedicle
bipolar cells are a _____ neuron and located in layers _____
bipolar cells:
- primary neuron
- in layers 5, 6, 7
list the 3 types of bipolar cells
- rod bipolar
- midget bipolar
- flat bipolar
what are the rod bipolar connections and size?
- connects only to rods
- large cell body and dendritic tree
where do the midget bipolar cells have connections?
- involved in 1:1:1 relationship
- found in macula
what are the flat bipolar connections?
- connects with several cones
- polysynaptic
ganglion cells are a ______ neuron and found in layers ____
ganglion cells
- secondary neuron
- layers 7, 8, 9
what is different about the ganglion cell layer in the macula vs. rest of retina?
at the macula, there are more rows of ganglion (8-10 row) but in rest of retina the ganglion cell layer is a single row
what are the two groups of ganglion cells?
- diffuse
2. monosynaptic (midget)
what is the nerve fiber layer made of?
of axons from ganglion cells headed towards the optic nerve and eventually traveling to the visual cortex
where do the the axons from the nerve fiber layer terminate?
in the midbrain in a structure called the lateral geniculate body
2 types of horizontal integration cells
- horizontal
2. amacrine
where are horizontal cells located?
in the bipolar cell layer (INL) closest to the synapse between photoreceptors and bipolar cells
what is the function of the the horizontal cells?
it is a synapse which can enhance or depress the signal between photoreceptor and bipolar cell
what synapse can the amacrine cell enhance or depress?
the synapse between the bipolar and ganglion cell
what are glial cells?
supportive, non-conducting cells that act like “glue”
functions of the fibers of Mueller
stores glucose and structurally fills in space
where are the Mueller cells found?
found in 6 layers and also contributes to ILM (layer 10) and ELM (layer 3)
the cell body of the Mueller cell is found in what layer?
layer 6
