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Where does the first action potential occur in a neuron?
Or, where does the action potential begin in a neuron?
At the axon hillock
What are neurotransmitters?
Chemical messengers that carry signals between nerve cells in the brain and body
What prevents action potentials from moving backwards?
The refractory period and the sequential nature of ion diffusion
What are glia cells
any of the cells that hold nerve cells in place and help them work the way they should
What is the function of myelin sheaths?
They insulate axons, preventing ion movement and increasing signal speed
Which cells form myelin sheaths in the PNS?
Schwann cells
What is saltatory conduction?
A process where the action potential jumps between unmyelinated nodes, increasing speed
What disease results from the destruction of myelin?
Multiple sclerosis
What would happen if the myelin sheath was damaged?
The action potential would fire, but the signal may be lost traveling down the axon
What are the functions of astrocytes?
structural support
metabolic functions
blood-brain barrier maintenance
neurotransmitter regulation
What is the role of oligodendrocytes?
The provide myelination in the CNS, insulating multiple neurons at a time
Where does a chemical neuron signal occur?
Between neurons via neurotransmitters
Where does an electrical neuron signal occur?
Within the neuron
What is exocytosis in neural communication?
The process of vesicles fusing with the presynaptic membrane to release neurotransmitters
What are ligand-gated ion channels
Channels that open or close when neurotransmitters bind to them, affecting ion flow
What does EPSP stand for?
Excitatory postsynaptic potential
What does the excitatory postsynaptic potential do
A positive change in the membrane potential that increases the likelihood of neuron firing
What does IPSP stand for?
Inhibitory postsynaptic potential
What does the inhibitory postsynaptic potential do?
A negative change in membrane potential that decreases the likelihood of neuron firing
What is neural integration?
A process of a neuron combining multiple inputs to decide whether to fire
What is temporal summation?
Multiple signals from the same neuron occuring in rapid succession to trigger an action potential
What is spatial summation?
Signals from multiple neurons combing to reach the action potential threshold
What triggers the release of neurotransmitters at the synapse?
The influx of calcium ions through voltage-gated calcium channels in the presynaptic neuron
Where is calcium concentration higher before neurotransmitter release?
Outside the synapse
How does calcium cause neurotransmitter release
they enter the synaptic terminal, causing vesicles to move, fuse with the membrane, and release neurotransmitters
What would happen if calcium voltage-gated ion channels were blocked
It would prevent neurotransmitter release, reducing the likelihood of the postsynaptic neuron firing
What is influx in calcium?
Calcium ions move into the cell
What is efflux of calcium?
Calcium ions move out of the cell
Where are the nodes of ranvier?
On the axon with the myelin sheaths
What is the function of a node of ranvier
essential for the transmission of electrical impulses along the axons
What does the arrival of an inhibitory postsynaptic potential do?
ligand-gated Cl- channels open allowing chloride ions to flow into the postsynaptic neuron
What does the arrival of an excitatory postsynaptic potential do?
ligand-gated Na+ channels open, allowing sodium ions to flow into the postsynaptic neuron
What activates the ligand gated ion channels
EPSP and IPSP
What activates the voltage gated ion channels
The difference in charge of the interior and exterior of the cell
If IPSP and an EPSP of equal magnitude fired, would it fire?
No
