Neural Communication Flashcards
What are two factors that affect action potential velocity? How do these two factors have to be to promote the potential traveling faster
Magnitude of the axon’s diameter, myelination
Larger diameter and more myelination - faster
What is in-between myelin sheaths
nodes of Ranvier - filled with voltage gated Na/K channels
Conduction in myelinated vs unmyelinated axons
Un M - continuous, slower as signal or potential has to regenerate at every channel opening
M - SALTATORY, myelin stops any ions from liking out, potential regenerates only at nodes of Ranvier, makes signal faster. It’s like action potential is jumping from one node to another which speeds it up
Two types of synapses location wise
Axodendritic - between synapse and dendrite
Axosomatic - between synapse and soma
What causes neurotransmitters to be released
As action potential travels down axon, the change in voltage triggers a Ca voltage gated channel to open, letting calcium into the neuron triggering the release of neurotransmitters
Ca goes into axon terminal, causes vesicles filled with neurotransmitters to bind to the membrane and release the neurotransmitters
What is the extracellular fluid between the axon terminal of the pre-synaptic neuron and the dendrites/axon hillock of the post-synaptic neuron called
Synaptic cleft
How do neurotransmitters cause post-synaptic neurons’ channels to open
Binds to them and since they’re chemically gated they open cousin a graded potential
Three ways to get rid of neurotransmitters after a graded potential has been achieved
Taken back into the presynaptic neuron, defuse away from synaptic cleft, or degraded by enzymes
Is the same neurotransmitter always released at a particular site
Yes, eg. a pathway to the muscle might be specific to contract it and it will only do that, while another will only relax it
What is a depolarising graded potential also called
Excitatory postsynaptic potential (EPSP)
What is a hyper polarising potential also called
Inhibitory postsynaptic potential (IPSP)
Channels stimulated in EPSP vs IPSP
EPSP - Na to flow in as well as some K might com out but overall the ICF becomes less negative
IPSP - K channels for K to flow out (positive leaving ICF - more negative) and Cl channels for chlorine to flow in making ICF more negative
What is summation
The addition of all EPSP and IPSP a neuron receives
Two types of summation
Temporal and spacial
In what case is there no summation
When signals from other neurons are too far apart, RMP is achieved before another graded potential can be triggered meaning the threshold won’t be reached to trigger an action potential (no action)
Summation is adding up of gated potentials
How does temporal summation work
An action potential is triggered by a presynaptic neuron and very quickly a second one is triggered. These action potentials add or sum (summation) together, threshold is reached, and an action potential is triggered.
How does spatial summation work?
Two or more presynaptic neurons sending the same signal at the same time, signals add together, reach threshold, action potential triggered.
What is cancellation
When a neuron receives an EPSP and an IPSP at the same time and they cancel each other out
What triggers an action potential
Reaching threshold by the change in voltage caused by the graded potential
What channels can be found along the whole neuron
Leakage - always open, sodium potassium pumps, help maintain membrane potential
Channels at dendrites and soma
Chemically gated channels to be triggered to open by neurotransmitters, Na channels
Channels at axon hillock
Action potential first starts there, change in voltage, voltage gated channels like Na and K
Channels along axon
Voltag gated Na and K channels
Channels at axon terminal
Voltage gated Ca channel to release neurotransmitters
