The Reflex Arc

• What cells are responsible for quick reactions to pain?

  Neurons
• What structure do neurons form to facilitate quick reactions?

  A reflex arc
• What are the three types of neurons in a reflex arc?

  • Sensory neuron
  • Relay neuron
  • Motor neuron
• What color represents the sensory neuron in the diagram?

  Blue
• Where is the cell body of the relay neuron located?

  In the spine
• What does the cell body of a neuron contain?

  The nucleus of the cell
• What are the two main structures on the length of a neuron?

  Axon and dendrites
• What is the function of axon terminals?

  To transmit signals to the next neuron
• What is the synapse?

  The gap between two neurons
• What is the myelin sheath made of?

  Schwann cells
• What is the role of the myelin sheath?

  To protect the cell and increase transmission speed
• What is the muscle at the end of the motor neuron called?

  The effector
• How does a sensation get detected?

  Through sensory receptors
• What happens to the electrical signal when it reaches the axon terminal?

  It converts into a chemical signal
• Where is the relay neuron located?

  In the spine
• What happens after the relay neuron processes the signal?

  It passes information to the motor neuron
• What does the brain do after the body has moved?

  Processes the information to reduce tissue damage
• What does the motor neuron signal to the effector?

  To cause the limb to move
• What is the fastest neuron in the body?

  The alpha motor neuron
• How fast does the alpha motor neuron transmit information?

  At 119 meters per second
• What is proprioception?

  The sense of body position in space
• What is the speed of type C neurons?

  One mile per hour
• Why are type C neurons slow?

  They are smaller and unmyelinated
• What are the key components of a reflex arc?

  1. Sensory neuron
  2. Relay neuron
  3. Motor neuron
  4. Effector
  5. Synapse
• How does the reflex arc function in response to pain?

  1. Sensation detected by sensory receptors
  2. Electrical signal travels through the neuron
  3. Signal converts to chemical at axon terminal
  4. Relay neuron processes and sends to motor neuron
  5. Motor neuron activates effector to move away from danger