B3.1 The Nervous System

• What type of cells make up the nervous system?


  Nerve cells, also known as 'neurons'.
• What are the stages of a reflex arc?

  Stimulus>Receptor>sensory neuron>CNS and relay neuron>motor neuron>effector>response.
• Why is it important for reflexes to be rapid?

  To protect us from harm.
• What passes along nerve cells?

  Electrical impulses.
• What is the role of a receptor?

  To detect a stimulus.
• Sensory neurone.

  
• What is the role of a sensory neurone?

  To transfer a signal from a receptor to the CNS
• What are the 2 main types of effectors?

  1. Muscles.
  2. Glands.
• What is the gap between nerve cells called?

  A synapse.
• Receptor.

  
• How does a synapse transmit an electrical signal?

  When an electrical impulse reaches the end of a neurone, it causes the release of chemicals. (Neurotransmitters).

  These chemicals then diffuse across the synapse and stimulate the next neurone to carry another electrical impulse.
• Relay neurone.

  
• What is the central nervous system (CNS) composed of?

  Spine and the brain.
• What is the role of a relay neurone?

  To transfer an electrical signals between sensory neurone to motor neurons.
• What is the role of a motor neurone?

  To transfer signals from the CNS to an effector.
• Effector.

  
• Why are reflexes so fast?

  Reflex actions are fast because they are automatic and don't involve conscious parts of the brain.
• What is a reflex arc?

  An automatic response to a stimulus.
• How do neurones transmit information?

  As electrical impulses along the axon of a neurone
• What is the role of the axon in a neurone?

  It transmits electrical impulses
• How do sensory and motor neurones differ in structure?

  They have slightly different structures but both have branched endings (dendrites)
• What are the branched endings of neurones called?

  Dendrites
• What is the function of the myelin sheath surrounding some axons?


  It speeds up the electrical impulse
• What is the effect of having long neurones on impulse transmission?

  It speeds up the impulse
• Why does connecting with many short neurones slow down the impulse?

  Because it involves more synapses, which take time
• What is the connection between two neurones called?

  A synapse
• What are the key features of neurones that facilitate the transmission of electrical impulses?

  • Long axons for faster transmission
  • Myelin sheath to speed up impulses
  • Branched endings (dendrites) for connections with other neurones
  • Synapses for communication between neurones