Nervous system

• 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 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
• What is the primary function of neurons?


  To carry electrical impulses from one point to another
• How are neurons adapted to their function?


  They are long, thin, and have many branch connections
• What is a synapse?


  A connection between two nerve cells
• What happens when an electrical impulse reaches the end of a nerve cell?


  It causes the release of chemicals that diffuse across the synapse
• What is the role of sensory neurons in the nervous system?


  To carry information from receptors to the central nervous system
• What does the central nervous system consist of?


  The brain and spinal cord
• What is the function of motor neurons?


  To send impulses from the central nervous system to effectors
• What are effectors in the nervous system?


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


  • A nerve pathway for unconscious reflexes
  • Involves sensory neurons, relay neurons, and motor neurons
  • Enables rapid and automatic responses
• Why are reflexes beneficial?


  They allow for rapid and automatic responses to stimuli
• What happens when you touch a hot object?

  A reflex arc is activated to move your hand away quickly
• What is the role of receptor cells in the reflex arc?


  To detect stimuli such as pressure or temperature
• What happens to the impulse in the spinal cord during a reflex action?


  It is transferred to a relay neuron
• What is the function of the relay neuron in a reflex arc?


  To pass the impulse from the sensory neuron to the motor neuron
• How does the impulse travel back to the body in a reflex arc?


  Through a motor neuron to an effector
• What happens at the synapses between neurons?


  The electrical signal is converted to a chemical signal
• What is the total number of neurons in the human nervous system?


  Approximately 100 billion
• What is the primary role of the central nervous system?


  To process sensory information and send out orders
• How does the nervous system respond to changes in the environment?


  By detecting changes and sorting through information to respond
• What type of information do sensory neurons carry?


  Information about changes in the environment
• What is the role of the bicep in the reflex arc example provided?


  To contract and move the hand away from the stimulus
• What is the significance of the chemical signals at synapses?


  They allow communication between nerve cells