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
