Divisions of The Nervous System

• What are the two main parts of the human nervous system?

  The central nervous system (CNS) and the peripheral nervous system (PNS)
• What is the primary function of the nervous system?

  To collect information, process it, and direct bodily organs and muscles
• How does the nervous system transmit messages?

  By transmitting electrochemical messages
• What does the central nervous system (CNS) consist of?

  The brain and spinal cord
• What role does the spinal cord play in the CNS?

  It receives and transmits information to and from the brain and body
• What are sensory (afferent) neurons responsible for?

  Delivering information to the CNS
• What do motor (efferent) neurons do?

  Transmit information away from the CNS
• What does the somatic nervous system (SNS) control?

  Skeletal muscles
• How is the somatic nervous system characterized?

  It is a voluntary system under conscious control
• What does the autonomic nervous system (ANS) control?

  Internal organs and glands
• How is the autonomic nervous system characterized?

  It is an involuntary system not under conscious control
• What are the two branches of the autonomic nervous system?

  The sympathetic and parasympathetic branches
• What is the function of the sympathetic branch?

  It activates the stress response
• What neurotransmitter is released by the sympathetic branch?

  Noradrenaline
• What happens to the body during the fight-or-flight response?

  Heart rate and breathing increase, pupils dilate, and digestion stops
• What is the function of the parasympathetic branch?

  It decreases bodily activities
• What neurotransmitter is released by the parasympathetic branch?

  Acetylcholine
• What is homeostasis?

  A process by which the internal environment is maintained
• How do the sympathetic and parasympathetic systems work together?

  They regulate the internal environment by balancing each other's activities
• How many nerve cells are estimated to be in the human gut?

  About 100 million
• How does the number of nerve cells in the gut compare to a cat's brain?

  It is about as many as in a cat's brain
• What are the main functions of the nervous system?

  • Collects information from the environment
  • Processes this information
  • Directs bodily organs and muscles
  • Transmits electrochemical messages
• What are the components of the autonomic nervous system?

  • Sympathetic nervous system
  • Parasympathetic nervous system
• What are the effects of the sympathetic nervous system during stress?

  • Increases heart rate
  • Increases breathing rate
  • Dilates pupils
  • Stops digestion
• What are the effects of the parasympathetic nervous system during rest?

  • Decreases heart rate
  • Decreases breathing rate
  • Constricts pupils
  • Stimulates digestion
• What is the relationship between the sympathetic and parasympathetic systems in maintaining homeostasis?

  • They work together to maintain balance
  • Sympathetic activates stress responses
  • Parasympathetic promotes rest and recovery