Pacinian corpuscle

• What part of the specification does the pacinian corpuscle fall into?

  Nervous system
• What do receptors detect?

  Stimuli
• What is a stimulus?

  A detectable change in the environment
• Why is the ability to respond to stimuli important for organisms?

  It increases their survival rate
• What are the two key sections of the nervous system?

  • Central nervous system (CNS): brain and spinal cord
  • Peripheral nervous system (PNS): receptor cells, sensory neurons, motor neurons
• What are the three key receptors mentioned in the AQA specification?

  Pacinian corpuscle, rods, cones
• What happens when a stimulus is large enough?

  It establishes a generated potential
• What is required for an action potential to be initiated?

  Influx of sodium ions above -55 mV
• What occurs if the stimulus is not large enough?

  No action potential is generated
• What type of stimulus does the pacinian corpuscle respond to?

  Pressure
• Where are pacinian corpuscles primarily located?

  Deep in the skin, especially fingers and feet
• What is the structure of a pacinian corpuscle?

  A sensory neuron wrapped in connective tissue
• What type of channels are present in the sensory neuron of the pacinian corpuscle?

  Stretch mediated sodium ion channels
• What must happen for stretch mediated sodium ion channels to open?

  They must be deformed and stretched
• What happens to sodium ion channels when there is no pressure applied?

  They remain closed
• What is the resting potential of a neuron?

  -70 millivolts
• What occurs when pressure is applied to the pacinian corpuscle?

  Sodium ions diffuse into the neuron
• What is the threshold potential for generating an action potential?

  -55 millivolts
• What happens when enough sodium ions diffuse into the neuron?

  An action potential is generated
• Describe the process of how the pacinian corpuscle generates an action potential.

  1. Pressure applied to pacinian corpuscle
  2. Stretch mediated sodium channels open
  3. Sodium ions diffuse into neuron
  4. Inside neuron becomes more positive
  5. If threshold of -55 mV is reached, action potential occurs
• What is the role of the viscous gel in the pacinian corpuscle?

  It separates the layers of connective tissue
• What happens to the plasma membrane of the sensory neuron when pressure is applied?

  It stretches and deforms
• What is the result of sodium ions diffusing into the neuron?

  More positive ions inside compared to outside
• What is the final outcome when an action potential is generated?

  A response occurs