key concept 45.3 Mechanoreceptors Respond to Physical Forces

The cell membranes of mechanoreceptors have cation channels that open when the membrane is disturbed by physical forces. The intensity of the physical force is registered as a graded receptor potential, which in turn leads to either the release of neurotransmitter or the generation of action potentials. The amount of neurotransmitter release or the rate of action potentials tells the CNS the strength of the stimulus to the mechanoreceptor. A diversity of mechanoreceptor cells has evolved in different sensory systems. The functions of these cells range from interpreting skin sensations to sensing blood pressure to hearing and maintaining balance.

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  • A variety of pressure-sensitive receptors enable multiple modes of mechanosensation.

  • Stretch receptors in muscle spindles signal for contraction, and stretch receptors in tendons signal for relaxation.

  • As the frequency of the sound stimulus decreases, the stimulated region of the basilar membrane moves from basal to apical.

  • The ear converts sound waves in air to pressure waves in fluid that bend hair cells to create auditory sensation.