Physiology 1.11 Flashcards Preview

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Flashcards in Physiology 1.11 Deck (10)
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1
Q

How can the length constant λ be increased in a neuron?

A
  • bigger fibers (reduce internal resistance)
  • increase myelination (increase membrane resistance)
  • increase # of nodes of Ranvier
2
Q

How can the time constant τ be decreased in a neuron?

A
  • lower capacitance

- increase myelination (increase membrane resistance)

3
Q

What does myelin do in terms of membrane resistance and capacitance?

A
  • decrease capacitance

- increase resistance

4
Q

What is a Node of Ranvier?

A

regions of axon which separate the stretches of myelin on the myelinated axon

5
Q

How are action potentials shut off in the periphery?

A
  • fast inactivation of Na+ channel

- large outward K+ leakage current

6
Q

What is the site on a neuron where the input is integrated?

A

soma

7
Q

What is the membrane length constant λ?

A

decay of conductance over space

8
Q

What is the time constant τ ?

A

time required to charge the membrane

9
Q

What is capacitance?

A

amount of charge required to create a given voltage change

10
Q

How do action potentials differ in myelinated axons of neurons versus the trigger zone between the muscle spindle and axon?

A

threshold is raised in trigger zone (called spike threshold) and does not need to repolarize before firing again