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CH 19
Nerve Signaling
| Question | Answer |
|---|---|
| Q1: What is the resting membrane potential (RMP) of a neuron? | Approximately -70 millivolts (mV), with the inside of the neuron more negative than the outside. |
| Q2: What creates and maintains the resting membrane potential? | The sodium-potassium pump (3 Na⁺ out, 2 K⁺ in) and leak channels that allow passive ion movement. |
| Q3: What is depolarization? | A reduction in membrane potential, where the inside of the cell becomes less negative |
| Q4: What triggers an action potential? | When a stimulus causes the membrane potential to reach threshold (~–55 mV) at the axon hillock. |
| Q5: What is the all-or-none principle? | If threshold is reached, a full action potential occurs; if not, no action potential happens. |
| Q6: What is repolarization? | The return of the membrane potential to its resting negative value, due to K⁺ leaving the cell. |
| Q7: What is hyperpolarization? | When the membrane potential becomes more negative than the resting potential, usually due to excess K⁺ leaving the cell. |
| Q8: What is the refractory period? | A period following an action potential when the neuron cannot fire again immediately. |
| Q9: How does myelination affect impulse speed? | It allows for saltatory conduction, where the action potential jumps between nodes of Ranvier, greatly increasing speed. |
| Q10: What is the function of a ligand-gated ion channel? | It opens in response to a specific chemical (ligand), allowing ions to flow and initiating a local potential. |
| Q11: What are the three types of ion channels in neurons? | Ligand-gated channels – open with chemical binding Voltage-gated channels – open with membrane voltage changes Mechanically-gated channels – open with physical deformation |
| Q12: What is a synapse? | The junction where a neuron communicates with another cell typically via neurotransmitters. |
| Q13: What happens at the synaptic knob? | Neurotransmitters are released from synaptic vesicles into the synaptic cleft, binding to receptors on the postsynaptic cell. |
| Q14: What are neurotransmitters? | Chemical messengers that transmit signals across a synapse. |
| Q15: What is a ligand-gated ion channel? | A channel that opens when a specific ligand binds to it. |
| Q16: What does “allosteric binding site” mean? | A binding site located away from the ion channel that still controls the channel’s opening. |
| Q17: What are mechanically-gated ion channels? | Channels that open in response to stretch or physical deformation of the membrane. |
Created by:
RamsesL
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