Class 2 - Synaptic Transmission Flashcards
What 3 factors increase the velocity of nerve impulse transmission?
- local temperature (heat)
- wider diameter (briefer refractory period)
- myelination of the axon (saltatory conduction)
Describe how a nerve signal travels in saltatory conduction?
the signal jumps from node of ranvier to node of ranvier, as these are the only places along the axon that are exposed to the interstitial environment
Drugs like lidocaine/procaine decrease pain by…
blocking Na+ channels so that pain impulses cannot pass the obstructed region
Which classification of nerve fibre is mainly found communicating from the viscera to the CNS, and for ANS motor impulses from the CNS to ANS ganglia?
B fibers
Which classifications of nerve fibres are myelinated?
A + B
What are the three different types of synapses?
axoaxonic
axodendritic
axosomatic
A type fibres are used for…
touch/pressure
joint position
some temperature/pain sensations
motor impulses to skeletal muscle
Nerves that carry motor impulses to skeletal muscle are of what type?
type A
Do chemical or electrical synapses occur more often in the human body?
chemical
Postsynaptic neurons receive a ____ signal, which is converted to a _____ signal to be propagated onward
chemical, electrical
EPSP’s __polarize the postsynaptic neuron
depolarize
IPSP’s ____polarize the posynaptic neuron
hyperpolarize
The net summation of EPSP’s and IPSP’s determine whether an AP is generated at what location?
the ‘trigger zone’
Describe the location of the neurotransmitter binding site + ion channel on an ionotropic vs. metabotropic receptor
ionotropic: part of the same structure
metabotropic: not part of the same structure
When ACh binds to ionotropic receptors, it generates a ____ vs when binding to a metabotropic receptor, it generates a _____
EPSP
IPSP
Neurotransmitters are removed from the synaptic cleft by 3 possible ways:
diffusion
enzymatic degradation
reuptake back into cells
Acetylcholine, amino acids, biogenic amines, and nitric oxide are considered ____ neurotransmitters
small-molecule
Neuropeptides include…
endorphins and dynorphins
substance P
Glutamate and aspartate are both ____ neurotransmitters
excitatory
GABA and glycine are ____ neurotransmitters
inhibitory
GABA and glycine are ____ neurotransmitters
inhibitory
Describe a ‘diverging’ neural circuit
one presynaptic neuron synapses with multiple postsynaptic neurons
Describe a ‘converging’ neural circuit
multiple presynaptic neurons synapse with one postsynaptic neuron (expanding)
Describe a reverberating neural circuit
nerve impulses that were initially activated in response to stimuli are continuously reactivated (like a positive feedback loop)
Describe a parallel after-discharge circuit
input from one presynaptic neuron passes down two separate but parallel pathways that eventually converge to one postsynaptic neuron
Nerves may only be repaired in the PNS if…
the neuron body and Schwann cells are unaffected
What is Wallerian degeneration?
when the axon distal to a nerve injury degenerates
How does the neurolemma aid in nerve regeneration in the PNS?
by forming a regeneration tube around the axon
Biogenic amines are involved in…
regulation of affective states - mood, motivation, feelings, self-awareness, consciousness, personality…
Describe the activity of nitric oxide in the CNS
formed on demand, acts immediately and briefly
thought to play a role in memory and learning
The opioid neuropeptides are called…
endorphins and dynorphins
What is the role of substance P?
transmission of pain information from peripheral receptors to PNS
What triggers the release of neurotransmitters into the synaptic cleft?
Ca++ channels open and allow Ca++ to enter the synaptic end bulbs, which promotes the release of NT by exocytosis
