Module 8 - Transmission Flashcards
What are the two types of transmission
electrical - within neuron
Chemical - between neurons
What is attenuation
basically signal being lost along the wire
Why is attenuation in dendrites not that big a deal
they’re short
And lots of inputs, so starting signal is very big
how is dendritic transmission passive
does not involve a wave of action potentials
λ is distance when V drops to what percentage of V at 0
37%
What does length constant depend on
Rm (resistance of insulator) -should be high
Ri (resistance of conductor) - should be low
And diameter - should be high
what 2 glial cells make myelin and where
oligodendrocyte - CNS
schwann cell - PNS
important characterisitic about nodes of ranvier
vry high density of Na channels
especially compared to the axon under the myelin
what does higher density of channels in node allow for
allows the action potential to rise quicker
what 2 things allow speed gain of transmission
density of na channels at nodes
decreased capacitsance of memb
what is squid axon used for
fat ass axon - voltage clamp method, experimentation and stuff
why does squid not use this big neuron in its whole nervous system
large enrgy cost that comes with it
lots of energy needed to power its transmission
Which of the following parts of a neuron is covered with myelin?
internode
how many Na channels in a node?
~1200 per micromtre^2
neuron with fasted transmission
A alpha fibre
what neuron has no myelination
C fibre
what autoimmune response attacks oligodendrocytes
multiple sclerosis
types of MS
- primary progressive MS (less common)
- relapsing remmiting MS
which usually progresses into - secondary progressive MS
MS treatments
- steroids
- treat specific symptoms
2 ways of diagnosing MS
visual evoked potential test
MRI
what result in a VEP test suggests MS
delayed electrical responses
what result in MRI suggests MS
sclerotic placques
diff parts of the brain at diff times that correlate to symptoms
how can we synthesise vit D
from our steroid precursors via UVB light
guilliain barre syndrome
autoimmune for schwann cells
so no myleination of PNS
(linked with food poisioning, cytomegalovirus, and covid)
