8.1 Flashcards
how many neurons in the body?
10^12
neuron structure
body
dendrites
axon
action of myelin
lipid insulator
increases membrane resistance
force current to flow along the axon interior
what are Nodes Of Ranvier?
small breaks every 1-2 mm
saltatory conduction
Aa fiber conduction velocity
70-12 m/s
Ab fiber conduction velocity
30-70 m/s
A delta fiber conduction velocity
5-30 m/s
C fiber conduction velocity
0.5-2.5 m/s
which fiber is madiator for pain?
A delta
also C
whar are the 3 ways of coding information in the NS?
- labeled line (like the fibers carring info about vision)
- spatial map (2 neighboring points on the skin)
- temporal pattern (timing of AP)
we do summation of
EPSP
IPSP
what is the depolarize rannge of EPSP?
1-5 mV
lasts for ms
Most common NT of EPSP?
Glu
What are the 2 R for Glu?
Ionotropic (AMPA,NMDA)
Metabotropic (mGluR 1-8)
Describe AMPA R
Permeable for univalent cations
Na+ influx
Can lead to Depol.
Describe NMDA R
Permeable for univalent cations and Ca++ Na+ and Ca++ influx Depol. must have already happen in order for them to open stronger response (Long Term Potentiation)
Describe Metabotropic (mGluR 1-8)
all Gi
except 1 and 5 which are Gq
most frequent NT for IPSP
GABA
R types for GABA?
GABA A
GABA B
Describe GABA A Receptor
pentameric ligand gated Cl- channel
Describe GABA B Receptor
Gi coupled
they open inward rectifying K+ channels (Kir)
create slower Hyperpolarization
2 ways for summation of PostSynaptic Summation
Temporal
Spatial
describe Temporal summation
amount of time btw. the PSP’s
we need them to be close in order to sum them
A+A (after some time)
describe Spatial summation
summation of PSP’s from different input at the same time
A+B
AP frequency is directly proportional to
the summed PSP Amplitude
what is non-adapting neuron?
quickly depolarize and repolarize
can maintain high frwquency of AP
what is adapting neuron?
also havs slowly-activating voltage gated K+ channels
it provides resistance to depolarization
what is rythmic bursting neuron?
have voltage gated Ca++ channels
and Ca++ activated K+ channels (hyperpolarization of the cell)
what is burst neuron?
in thalamus neurons
EPSP leads to T-Type channel opening
what is synaptic placticity?
tha ability of synaps to change their strength
describe what is potential?
difference in charge btw outside and inside
how does Long Term Potentiation can increase synaptic strength?
high frequency stimulation -> AMPA-R activity -> depol -> NMDA-R activity -> [Ca++] high -> CAM-Kinase -> AMPA-R phosphorylation and more activation
how many Glial cells?
x10 more than neurons
different types of Astrocytes?
fibrous protoplasmic radial glial Muller Bergmann (cerebellum)
function of astrocytes?
- provide fuel
- rgulate [K+]
- regulatr pH of EC fluid
- take up Glu
- modulate cerebral blood flow
describe how astrocytes provide fuel for neurons?
release lactate through MCT-1
neuron use MCT-2 to bring lactate inside
convert it back to pyruvate
why is it possible to have K+ channels for influx in the astrocytes?
astrocytes have very negative membrane potential
so K+ wants to travel inside
describe how astrocytes modulate cerebral blood flow?
Glu activates mGluR-1 or mGluR-5 -> Gq -> Ca++ up -> PGE2 and NO release -> vasodilation -> more blood flow to the active neurons
what makes Myelin and where
Oligodendrocytes- CNS
Schwann cells- PNS
what are the macrophages of the CNS
Microglial cells
which cells produce the CSF?
Ependymal cells
