the nervous system + reflex arc

• What are the two organ systems that help large multicellular organisms communicate internally?

  The nervous system and the endocrine system
• Why do large multicellular organisms need a communication system?

  To coordinate behavior and respond to their surroundings
• What are the main topics to know about the nervous system?

  • Structure of a nerve cell
  • Structure of the whole nervous system
  • How a reflex arc works
• What is another name for a nerve cell?

  Neuron
• How are neurons adapted to carry electrical impulses?

  They are long, thin, and have many branch connections
• What is the function of a synapse in neuron communication?

  It allows the transfer of chemical signals between nerve cells
• What happens when an electrical impulse reaches the end of a nerve cell?


  It causes the release of chemicals that diffuse to the next nerve cell
• How does the structure of the nervous system relate to its function?

  The long and branched structure of neurons allows efficient message transmission
• What are the two main parts of the central nervous system?

  The brain and the spinal cord
• What role do sensory neurons play in the nervous system?

  They carry information from receptors to the central nervous system
• What does CNS stand for?

  Central Nervous System
• How does the central nervous system respond to sensory information?

  It decides what needs to be done and sends orders via motor neurons
• What are effectors in the nervous system?

  Muscles or glands that respond to impulses
• What is a reflex arc?

  A nerve pathway that underlies unconscious reflexes
• Why are reflexes beneficial for organisms?

  They allow rapid and automatic responses to stimuli
• Describe the process of a reflex action when touching a sharp object.

  The sensory neuron carries the impulse to the spinal cord, which transfers it to a relay neuron, then to a motor neuron, causing a muscle contraction
• What is the role of receptor cells in the reflex action?

  They detect stimuli such as pressure from a sharp object
• What happens at synapses during neuron communication?

  The electrical signal is temporarily converted to a chemical signal
• What are the steps involved in a reflex arc?

  1. Stimulus detected by receptor cells
  2. Sensory neuron carries impulse to spinal cord
  3. Relay neuron transfers impulse within spinal cord
  4. Motor neuron carries impulse to effector
  5. Effector (muscle) contracts to respond