Chapter 41 Neural Signaling Lecture 11
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40 Terms
What are the three main parts of a neuron?
Dendrites, cell body (soma), and axon.
What is the function of dendrites?
Receive incoming signals.
What is the function of the axon?
Transmit signals away from the cell body.
What type of neuron carries signals toward the CNS?
Sensory (afferent) neuron.
What type of neuron carries signals away from the CNS?
Motor (efferent) neuron.
What is the role of interneurons?
Integration and processing within the CNS.
What does the PNS primarily do?
Conveys signals.
What does the CNS primarily do?
Computation and decision-making.
What is electrical potential?
Stored energy from separated charges
What is the resting membrane potential of a neuron?
Approximately –70 mV.
What pump creates Na⁺ and K⁺ gradients?
Na⁺/K⁺-ATPase pump.
How many Na⁺ and K⁺ ions does the pump move?
3 Na⁺ out, 2 K⁺ in.
Why is the inside of the neuron negative at rest?
K⁺ leaks out through K⁺ leak channels, leaving negative charge behind
What is an electrochemical gradient?
A combination of chemical and electrical gradients.
What is equilibrium potential?
The voltage where chemical and electrical forces are equal for an ion.
Which equation calculates equilibrium potential?
Nernst equation.
What is the equilibrium potential for K⁺?
About –75 mV.
What equation calculates overall membrane potential?
Goldman equation.
At rest, which ion mostly determines membrane potential?
K⁺.
Why is the Na⁺/K⁺ pump considered electrogenic?
It contributes to the negative resting potential.
What is the threshold potential?
About –55 mV.
What happens if threshold is not reached?
No action potential occurs.
What does “all-or-none” mean?
Action potentials either fully occur or not at all
What ion causes depolarization?
Na⁺.
What happens to Na⁺ channels during depolarization?
They open rapidly.
What is the peak membrane potential during depolarization?
Around +40 mV.
Why is depolarization a positive feedback loop?
Opening Na⁺ channels causes more depolarization, opening more Na⁺ channels.
What causes repolarization?
K⁺ channels open and K⁺ exits the cell.
What happens to Na⁺ channels during repolarization?
They close.
Why does hyperpolarization occur?
K⁺ channels remain open slightly too long
What is hyperpolarization?
Membrane potential becomes more negative than resting potential.
What is the refractory period?
A brief time when Na⁺ channels cannot reopen.
Why does the refractory period matter?
Ensures one-way signal transmission.
Do action potentials decrease in strength as they travel?
No, they are regenerated and do not diminish.
What is saltatory conduction?
Action potentials jumping from node to node.
What structures allow saltatory conduction?
Nodes of Ranvier.
What produces myelin in the CNS?
Oligodendrocytes.
What produces myelin in the PNS?
Schwann cells.
How does myelin increase speed?
It reduces charge leakage and allows jumping between nodes.
What disease destroys myelin?
Multiple Sclerosis.
