Nervous System 2 Flashcards
Afferent corresponds to what type of information going in which root? efferent?
sensory/dorsal or posterior
motor/ventral or anterior
motor neurons are located ONLY where?
anterior horn
interneurons are located where?
both anterior and posterior horn.
dura mater is made up of what?
connective tissue
what is the layer that surrounds one axon? multiple axons (fassicle)? bunch of fassicles?
endoneurium, perinerium and epineurium.
central canal in spinal cord is lined with what?
ependymal cells.
grey matter is made up of? white matter? which one would have fewer cell nuclei?
cell bodies
axons/dendrites
white matter because the axons are mylenated therefore would appear white.
what is neuropil?
axon + dendrite
central canal is lined with what type of cells?
simple cuboidal ependymal cells (or tanocytes)
unipolar neurons are what type of neuron? how do they appear?
sensory
round or acinar because they only have one process dont look like neurons.
what are the three meninge layers? they are made of what kind of tissue?
all made up of connective tissue.
- dura mater: firboelastic, subdural space underneath very small
- arachnoid space: fibrous, lined by squamous cells, subarachnoid space underneath large space containing BV and CSF
- pia mater: collagen, elastin and fibroblasts, delicate layer
BBB contains which junctions? fenestrated or non? what is allowed to pass?
tight junctions, non fenestrated, glucose can freely pass (brains E).
once CSF makes it to subarachnoid space from 4th ventricle (choroid plexus) where does it go?
to venous blood at superior saggital sinus.
nerves are made up of many what? endoneurium surrounds what? perineurium? epineurium?
axons
axons (around myelin)
fassicles of axons
various fassicles (surrounds nerves)
how would you tell difference between muscle and nerves in picture?
the way the cells appear. in muscle, profile of cells. in nerves, axons appear as many tiny dots NOT cell like.
ganglion cell axons exit at optic disc and pass through what before going to LGN?
lamina cribosa.
approximately how many photoreceptors? ganglion cells?
125 million rods and cones
1 million ganglion cells
therefore many photoreceptors for every 1 ganglion cell
the inner nuclear layer contains nuclei of what 5 types of cells?
amacrine, bipolar, ganglion, horizontal, photoreceptors, mueller (more recently interplexiform cells added)
which are larger rods or cones? we have more of which?
cones are larger
rods
in cones we have two invaginations for synaptic contact (this area is called what?) which are?
synaptic area= pedicle
one bipolar and one horizontal invagination
in rods, the synaptic area is called? how many extensions (as opposed to invaginations) and what are they?
spherule
3. 1 bipolar and 2 horizontal
RPE is responsible for digesting what? if it cant do this what happens?
old photopigment (old rods and cones). if it cant do this, it partially digests the material and buts it beneath RPE cells into or on bruchs membrane= drusen.
what is located at 0 degrees? does the blind spot have rods or cones? where does the retina end? where is the blindspot located?
the fovea (high acuity, highest number of cones).
NO
ora serratta
12 degrees nasal (this is where ganglion cells leave, central retinal artery enters and central retinal vein enters, also where lamina cribosa is located).
optic disk is located to where to the fovea? what appears darker, your optic disk or macula?
optic disk is nasal to the fovea
macula due to pigmentation
what two pigments are located in the macula (darkened region)? the macula is how big in diameter?
lutein and zeaxanthin (both are xanthophylls)
there is also taller and darker RPE cells
5mm
what are the layers of the fovea? what is unique about the first layer?
central smallest layer= foveola, fovea, parafovea, perifovea (outer most)
foveola is avascular and ONLY has cones
what is the distance between the macula and the optic disk?
3-4mm
what is the fovea? and how large is it?
depression in center of retina (pushes ganglion cells out of the way), 1.5mm.
Which layer is thicker, parafovea or peripfovea?
parafovea (thickest ganglion and INL layer, 7-12 cell layers)
perifovea (4 cell layers, ends when it reaches 1 cell layer)
in the far peripheral retina what happens to the rods?
they disappear (nuclear and plexiform layers merge) (cones disappear much faster than rods)
ora serratta is located how far in front of equator?
5mm.
nasal fibres entering the optic disk, do they create arculate patterns? if not what do?
NO (they go through macula)
temporal fibres, these do NOT go through macula they go around, they form superior and inferior archs around macula which make arcuate patterns.
what is the papillomacular bundle (PM)?
direct line of deep fibres from the fovea to the temporal edge of optic disk.
the further the fibres are in the periphery what does this mean? the closer they are to the fovea?
further out means more superficial, closer to vitreous
closer in means more deep, closer to ganglion cells.
optic nerve is surrounded by what?
3 meninges (dura, arachnoid and pia, part of CNS).
at the optic disk (blind spot), are there cells present?
NO and NO plexiform layers. millions of axons from ganglion cells present going through lamina cribosa.
what is the physiological cup?
indentation region at very center of optic disk.
the optic nerve head (disk) is elongated vertically, what are the dimensions? disk lacks all layers except for? what color is it?
vertical 1.9mm x 1.7mm horizontally
fibres and ILM
pale due to no RPE, lamina cribosa also has holes giving it a lighter color, capillaries give it a pinkish color
outer layers of retina supplied by? inner? once central retinal artery enters the optic nerve what happens?
choroidal capillaries
central retinal artery
it branches into superior and inferior branches and gives rise to two sets of capillaries 1. superficial (ganglion cell layer) 2. deep (at junction between INL and OPL).
the plexiform and photoreceptors are nourished by what circulation?
outer supply (choroidal) NOT inner.
blood supply to the optic nerve comes from what four sources?
- branches from central retinal artery
- branches from circle of zinn (anastomoses between short ciliary arteries and pial arteries)
- choroidal branches
- pial branches (go directly to pia).
meinigitis, infection of the meninges normally occurs at what level?
arachnoid
