Action Potentials - A Short Quiz

Be bold with your answers. The knowledge you construct defines you.

1. What ion enters a neuron causing depolarization of the cell membrane?
   1. sodium
   2. chloride
   3. potassium
   4. phosphate
2. Voltage-gated Na+ channels open upon reaching what state?
   1. resting potential
   2. threshold
   3. repolarization
   4. overshoot
3. What does a ligand-gated channel require in order to open?
   1. increase in concentration of Na+ ions
   2. binding of a neurotransmitter
   3. increase in concentration of K+ ions
   4. depolarization of the membrane
4. What does a mechanically gated channel respond to?
   1. physical stimulus
   2. chemical stimulus
   3. increase in resistance
   4. decrease in resistance
5. Which of the following voltages would most likely be measured during the relative refractory period?
   1. +30 mV
   2. 0 mV
   3. -45 mV
   4. -80 mV
6. Which of the following is probably going to propagate an action potential fastest?
   1. a thin, unmyelinated axon
   2. a thin, myelinated axon
   3. a thick, unmyelinated axon
   4. a thick, myelinated axon
7. What does it mean for an action potential to be an “all or none” event?
   The cell membrane must reach threshold before voltage-gated Na+ channels open. If threshold is not reached, those channels do not open, and the depolarizing phase of the action potential does not occur, the cell membrane will just go back to its resting state.
8. The conscious perception of pain is often delayed because of the time it takes for the sensations to reach the cerebral cortex. Why would this be the case based on propagation of the axon potential?
   Axons of pain sensing sensory neurons are thin and unmyelinated so that it takes longer for that sensation to reach the brain than other sensations.

With the exception of this sentence the action potential and quiz is from; https://opentextbc.ca/anatomyandphysiology/chapter/12-4-the-action-potential

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