Question
click below
click below
Question
Normal Size Small Size show me how
Anatomy Exam 3
Question | Answer |
---|---|
During which phase of an action potential are voltage-gated K+ channels open, while voltage-gated Na+ channels are closed? | Repolarizing phase |
All gated Na+ and K+ channels are closed | Resting State (First stage) |
Na+ channels open, allowing Na+ entry | Depolarization (Second stage) |
Na+ channels are inactivating. K+ channels open, allowing K+ to exit. | Repolarization (Third stage) |
Some K+ channels remain open, and Na+ channels reset | Hyperpolarization (Fourth stage) |
Which statement best describes the role of leakage (nongated) channels? | Leakage channels help maintain the resting membrane potential. |
Which of the following best describes the all-or-none phenomenon? | An action potential occurs completely when threshold is met and does not happen at all if threshold is not met. |
A stimulus that fails to generate an action potential is called a ________. | subthreshold stimulus |
All voltage-gated Na+ and K+ channels are closed during which of the following stages? | The resting state of a neuron |
A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has already responded because __________. | the neuron is in the refractory period |
Saltatory conduction refers to _______. | a conduction process in myelinated axons where the electrical signal appears to jump from gap to gap along the axon |
Multiple sclerosis is __________. | an autoimmune disease that leads to destruction of the myelin sheaths in the CNS |
Which of the following describes a change of membrane potential from -70mV to -75mV? | Hyperpolarization |
Excessive potassium efflux as a result of relatively slower closure of the potassium gates corresponds to what part of an action potential curve? | The hyperpolarization phase of an action potential |
How can the central nervous system determine whether a particular stimulus is intense or weak? | Stronger stimuli generate action potentials more frequently than weaker stimuli. |
Which of the following membrane ion channels open and close in response to changes in the membrane potential? | Voltage-gated channels |