Rod and cone cells

• Who is the presenter of the A Level Biology video?

  Miss Estrich
• What is the main focus of the video?

  The pacinian corpuscle receptor
• What part of the specification does the pacinian corpuscle fall under?

  The nervous system
• 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 and peripheral nervous systems
• What does the central nervous system consist of?

  The brain and spinal cord
• What does the peripheral nervous system include?

  Receptor cells, sensory neurons, motor neurons
• What is the specific receptor discussed in the video?

  The pacinian corpuscle
• What do receptors detect?

  Specific stimuli
• What are the two types of photoreceptors mentioned?

  Rods and cones
• What happens if the stimulus is large enough?

  It can generate an action potential
• What is the threshold for generating an action potential?

  At least minus 55 millivolts
• What is required for a response to occur?

  A sufficient influx of sodium ions
• What is the role of sodium ions in action potentials?

  They help depolarize the neuron
• 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 found in the sensory neuron of the pacinian corpuscle?

  Stretch mediated sodium ion channels
• What causes the sodium ion channels to open in the pacinian corpuscle?

  Pressure applied to the sensory neuron
• What happens to sodium ion channels when there is no pressure?

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

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

  Sodium ions diffuse into the neuron
• What is the result of sufficient sodium ions entering the neuron?

  Action potential is generated
• What is the process of generating an action potential in the pacinian corpuscle?

  1. Pressure applied to pacinian corpuscle
  2. Stretch mediated sodium ion channels open
  3. Sodium ions diffuse into the neuron
  4. Neuron depolarizes to minus 55 millivolts
  5. Action potential is generated
• What are the key components of the nervous system?

  • Central nervous system: brain and spinal cord
  • Peripheral nervous system: receptor cells, sensory neurons, motor neurons
• What are the characteristics of stretch mediated sodium ion channels?

  • Closed unless deformed
  • Open when pressure is applied
  • Allow sodium ions to diffuse in
• What happens during the resting state of a neuron?

  • Sodium ion channels are closed
  • Resting potential is maintained at minus 70 millivolts
  • No sodium ions enter the neuron
• What is the significance of the pacinian corpuscle in the nervous system?

  • Detects pressure stimuli
  • Initiates action potentials
  • Contributes to sensory perception