[Campbell Biology P.1158] Based on Figure 50.4 and the accompanying text, what is the primary... | Practice Question

Based on Figure 50.4 and the accompanying text, what is the primary mechanism by which the nervous system encodes the intensity of a stimulus received by a sensory receptor?

  • A: By increasing the amplitude of individual action potentials as stimulus intensity increases.
  • B: By varying the frequency of action potentials generated, with higher stimulus intensity leading to a higher frequency of action potentials.
  • C: By switching the production of action potentials completely on or off depending on the presence of a stimulus.
  • D: By varying the specific type of neurotransmitter released by the sensory receptor.

Explanation

Figure 50.4 clearly illustrates that 'Gentle pressure' leads to 'Low frequency of action potentials', while 'More pressure' leads to 'High frequency of action potentials'. The text further elaborates that 'The size of a receptor potential increases with the intensity of the stimulus. If the receptor is a sensory neuron, a larger receptor potential results in more frequent action potentials'. This indicates that stimulus intensity is encoded by the frequency of action potentials.