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Physiology

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Nerve Muscle Physiology

Question
4 out of 24
 

Continuous sub-threshold stimulus leading to sustained response and increase in threshold for action potential. This is known as? (AIIMS MAY 2013)



A Accommodation
B Adaptation

C Resistance
D Initiation

Ans. A (Accommodation)
  1. Slowly rising currents fail to fire the nerve because the nerve adapts to the applied stimulus, a process called accommodation.
  2. It is because slow opening voltage gated K channels also start to open to cause K efflux and balance Na influx via voltage gated Na channels, this leads increase in threshold for action potential.
  3. Once threshold intensity is reached, a full-fledged action potential is produced.
  4. Further increases in the intensity of a stimulus produce no increment or other change in the action potential as long as the other experimental conditions remain constant.
  5. The action potential fails to occur if the stimulus is subthreshold in magnitude, and it occurs with constant amplitude and form regardless of the strength of the stimulus if the stimulus is at or above threshold intensity.
  6. The action potential is therefore "all or none" in character and is said to obey the all-or-none law.

Nerve Muscle Physiology Flashcard List

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