Neurotransmission Flashcards
(88 cards)
Most neurons RMP is
-60 to -70 mV
The resting membrane potential is produced by which 3 things?
- ) Selective permeability of K+
- ) Osmotic and electrical forces
- ) Energy dependent Na+/K+ pump
A potential that does not reach threshold, however summation of these can reach threshold
Graded potential
Decrease over time and space
-can be excitatory or inhibitory
Graded potentials
The result of voltage-gated ion channels opening
-continued over time
Action potential
An all or none response
-Only excitatory
Action Potentials
Excitatory post-synaptic potentials (EPSPs) are examples of
Graded potentials
In EPSPs, depolarizing postsynaptic potentials = an influx of positive ions, usually a result from opening of
Na+ or Ca2+ channels
An influx of negative ions or efflux of positive ions
-Usually a result from opening Cl- or K+ channels
Hyperpolarization potentials
Hyperpolarization potentials are an example of an
-a form of graded potential
Inhibitory post-synaptic potential (IPSP)
Attenuate rapidly
Graded potentials
Graded potentials are summed and may reach threshold for an action potential if depolarization reaches the
Axon Hillock
Summation of graded potentials from one excitatory presynaptic neuron firing rapidly
Temporal Summation
Summation of graded potentials from two or more excitatory presynaptic neurons firing
Spatial summation
This depolarizes the neighboring membrane downstream, opening adjacent voltage-gated Na+ channels
Action potential propagation
Increase conduction velocity and membrane length constant
Larger axon diameter and increased myelination
Nodes of Ranvier are breaks in the myelination containing a very high concentration of voltage-gated
Na+ Channels
Action potentials ‘jump’ from one node to the next and are regenerated at each node. This concept is known as
Saltatory conduction
What are two types of demyelinating disease?
- ) Guillain-Barre Syndrome
2. ) Multiple Sclerosis
Damage to myelin of peripheral nerves, mainly motor nerves
-inflammatory process – viral exposure (1-2 weeks after infection)
Guillain-Barre Syndrome
Guillain-Barre syndrome is characterized by
Elevated protein in CSF
Autoimmune disorder caused by genetic predisposition and environmental exposure
Multiple Sclerosis (MS)
Characterized by multiple plaques of demyelinated CNS white matter
MS
More commonly effects optic nerve, deep cerebral white matter, cerebellar peduncles, brainstem, spinal cord
MS