Week 3: Neurotransmitters and Neuron Communication Flashcards
What is the Synapse?
The junction where the axon of a sending neuron communicates with a receiving neuron across the synaptic cleft (tiny fluid filled sacks)
What is an Ion?
electrically charged atoms or molecules (move as a result of biological electricity aka electric impulses).
Ions contain either a positive or a negative charge
What makes it possible for Ions to flow through the axon?
Cell membrane permeability
What is resting potential?
when a neuron carries a negative charge relative to the fluid outside of the cell
What is action potential?
the sudden and brief reversal of the resting potential.
“all of none law” - neuron either fires completely or it doesn’t
When a neuron is sufficiently stimulated by an incoming signal, ion channels begin to open in the cell membrane, allowing positive ions to flow into the axon
This inflow of positive ions causes the membrane potential to change abruptly to a positive value.
What is the myelin sheath?
White coating that wraps around the axon of some neurons to act as insulation
What is the refractory period of a neuron?
After firing, a neuron cannot fire again for 1-2 milliseconds
What are synaptic vesicles?
synaptic vesicles are located in the axon terminal and contain neurotransmitters.
When an action potential occurs, the synaptic vesicles move toward the cell membrane, fuse with it and release neurotransmitters into the synaptic clefts.
What are receptor sites?
Sites on the dendrites or cell body of a neuron that will interact only with specific neurotransmitters.
Each neurotransmitter has a distinctive shape (same as dendrites and somas). Therefore, neurontransmitters can only affect neurons that contain receptors with similar shapes.
Receptors will pick the neurotransmitter that matches most perfectly with itself.
What is reuptake?
when neurotransmitter is taken from the synaptic clefts back to the axon terminal for later use, thus terminating their excitatory or inhibitory effect on the receiving neuron.
What are excitatory and inhibitory effects that neurotransmitters have on neurons?
when a neurotransmitter enters a receptor site, its action is either excitatory (fires) or inhibitory (not fire).
because neurons can connect with thousands of other neurons at the same time, there will always be both excitatory and inhibitory influences on the neuron
For the neuron to fire, the excitatory influences must exceed the inhibitory influences of the neurotransmitter substances by a sufficient amount (the threshold)
What is a neurotransmitter?
chemicals that are released into the synaptic clefts from the axon terminal of the sending neuron, cross the synapse, and bind to appropriate receptors on the dendrites or cell body of the receiving neuron, influencing the neuron to either fire or not fire
