Sensory Receptor Cells (Cambridge International A-Level Biology)

Spec point — 15.1.4 · outline the role of sensory receptor cells in detecting stimuli and stimulating the transmission of impulses in sensory neurones

Sensory receptor cells

• A cell that responds to a stimulus is called a receptor cell

• Receptor cells are transducers

  • They **convert energy **in one form (such as light, heat or sound) into energy in an electrical impulse within a sensory neurone

• Receptor cells are often found in** sense organs** (e.g., light receptor cells are found in the eye)

  • Some receptors, such as light receptors in the eye and chemoreceptors in the taste buds, are specialised cells that detect a specific type of stimulus and influence the electrical activity of a sensory neurone
  • Other receptors, such as some kinds of touch receptors, are just the ends of the sensory neurones themselves

• When receptor cells are stimulated, they are depolarised

  • If the stimulus is very weak, the cells are not sufficiently depolarised and the sensory neurone is not activated to send impulses
  • If the stimulus is strong enough, the sensory neurone is activated and transmits impulses to the CNS