9.7

• How is information about the environment carried to the CNS?

  By sensory neurons
• What happens to the frequency of action potentials as the intensity of a stimulus increases?

  The frequency of action potentials increases
• What do different sensory neurons transmit information to?

  Different parts of the brain
• What occurs when several different types of sense organs are stimulated simultaneously?

  Multiple sensory inputs are processed together
• How is the interpretation of sensory information achieved?

  Through communication between different centres in the brain
• Where are the sensory receptors that detect the external environment located?

  In the skin, mouth, and head
• What are proprioceptors?


  Internal sense receptors that signal information about the position and movement of body parts
• How do sensory cells maximize the reception of a stimulus?

  They are grouped together as a sense organ
• What are the basic features shared by sensory organs?

  • Contain receptor cells sensitive to one class of stimulus
  • Sensitive mechanisms localized at receiving membranes
  • Accessory tissues to magnify, select, or filter stimuli
• What are the two types of photoreceptors in the human eye?

  Rods and cones
• What do cones respond to?

  Colour
• How are cones categorized?

  Into three types based on wavelength sensitivity: short, medium, and long
• What are rods sensitive to?


  Intensity of light
• What do mechanoreceptors respond to?

  Mechanical forces such as pressure or distortion
• Where are most mechanoreceptors found?

  In the skin
• What are the three main types of mechanoreceptors?

  1. Slowly adapting types (small or large receptive field)

  2. Rapidly adapting mechanoreceptors (small receptive field)

  3. Pacinian receptors (detect high frequency vibrations)
• What do slowly adapting mechanoreceptors primarily detect?

  Static stimulation, form, and roughness
• What do rapidly adapting mechanoreceptors perceive?

  Slipping
• What do Pacinian receptors detect?

  High frequency vibrations
• What do thermoreceptors detect?

  Changes in body temperature
• How many distinct types of thermoreceptors are there in mammals?

  Two
• What do nociceptors respond to?

  Damaging stimuli
• Where are nociceptors found?

  In the organs and skin
• What is the activation threshold for nociceptors?

  High
• What is the role of nociceptors in the body?

  To send signals that result in the perception of pain