1.4 Action Potentials Part 2 Flashcards
What does it mean that action potentials are self propagating?
ion channels along axon are prompted to open whenever the membrane potential depolarizes in the surrounding area
What does it mean that an action potential is an all or nothing response?
it either occurs or does not occur; no in between
Since there is no variation in the strength of an action potential how do we distinguish between severity?
number of neurons firing and the frequency of firing
What does it mean that transmission of nerve impulse are electrochemical?
electrical in the axon, chemical in the synapse, back to electrical in the axon
What happens when an action potential reaches the end of an axon?
voltage-gated calcium channels open allowing calcium to rush into the axon
What does the influx of calcium ions cause at the ends of axons?
causes vesicles that contain neurotransmitters to release the neurotransmitter into the synapse
What happens after neurotransmitters are released into the synapse?
sodium channels on the post synaptic neuron open causing a depolarization event
What is an example of an enzyme that inactivates a neurotransmitter?
acetylcholinesterase
What is needed to prevent continuous stimulation of the postsynaptic membrane?
short existance of neurotransmitter in the synapse
What are examples of how some neurons make sure the neurotransmitter only exists for a short while in the synapse?
- enzymes that degrade the neurotransmitter
- cells reabsorb the neurotransmitter
What are the neurotransmitters produced by the adrenal glands?
epinephrine
norepinephrine
What is dopamine?
specialized neurotransmitter that helps regulate emotional responses and muscle tone
What is the neurotransmitter found at neuromuscular junctions?
acetylcholine
What is a neuromuscular junction?
found in the PNS where a motor neurons meets a muscle
Where does the action potential in a muscle cell end up at?
sarcoplasmic reticulum
