Pressure receptors in the skin

• The pacinian corpuscle surrounds the sensory neurone ending
• The pacinian corpuscle are mechanoreceptors
• The pacinian corpuscle detects strong pressures on the skin
• Each corpuscle consists of a sensory neurone surrounded by a capsule with many layers of connective tissue
• More pacinian corpuscle in more sensitive skin and joints
• The pacinian corpuscle let us know which way joints are facing
• When pressure is added to the lamellae, they deform and stretch. As it stretches, sodium ions move in and cause a neural impulse
• Structure of the pacinian corpuscle

  A) sensory neurone ending

  B) Capsule

  C) Layers of connective tissue

  D) Blood capillary

  E) Sensory neurone axon

  
• Signalling by the pacinian corpuscle

  1. Mechanical pressure distorts the neurone cell membrane (lamellae) and open sodium channels
  2. The stronger the pressure, the more Na+ channels open
  3. Na+ diffuses in, causing depolarisation, this is the generator potential
• The membrane of the sensory nerve ending contains stretch-mediated Na+ ion channel proteins
• Each receptor is adapted to detecting one type of stimulus
• Any receptor acts as a transducer- converts the energy they sense into a nerve impulse
• A threshold needs to be exceeded to produce a generator potential