Nervous System short version

• What are the two systems that function to maintain life conditions in the body?

  The nervous system and the endocrine system
• How does the nervous system respond to regulate body activities?

  It responds rapidly with nerve impulses
• What are the main functions of the nervous system?

  • Perceptions
  • Behaviors
  • Memories
  • Initiates all voluntary movements
• What percentage of total body weight does the nervous system make up?

  About 3%
• What are the two main divisions of the nervous system?

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
• What is the field of medicine that deals with the functions of the nervous system?

  Neurology
• What is a neurologist responsible for?

  Diagnosis and treatment of disorders of the nervous system
• What does the central nervous system consist of?

  • Brain: located in the skull, contains approximately 85 billion neurons
  • Spinal cord: connected to the brain, surrounded by vertebral column, contains approximately 100 million neurons
• Where is the brain located?

  In the skull
• How many neurons does the brain contain approximately?

  Approximately 85 billion neurons
• What connects the spinal cord to the brain?

  The foramen magnum
• How many neurons does the spinal cord contain approximately?

  Approximately 100 million neurons
• What are the main sources of the central nervous system?

  • Thought
  • Emotions
  • Memories
  • Signals that stimulate muscle contraction
  • Signals that stimulate gland secretion
• What does the peripheral nervous system consist of?

  • All nervous tissue outside the central nervous system
  • Components include nerves and sensory receptors
• What is a nerve?

  A bundle of hundreds to thousands of axons, associated connective tissue, and blood vessels
• How many pairs of cranial nerves emerge from the brain?

  12 pairs
• How many pairs of spinal nerves emerge from the spinal cord?

  31 pairs
• What does each nerve in the peripheral nervous system do?

  Follows a specific path and serves a specific region of the body
• What are the two divisions of the peripheral nervous system?

  • Sensory division
  • Motor division
• What is the function of the sensory division of the peripheral nervous system?

  • Has sensory receptors that monitor changes in the environment
  • Conveys input into the CNS from somatic and special senses
• What types of senses does the sensory division convey input from?

  Somatic senses and special senses
• What are the types of somatic senses?

  • Tactile
  • Thermal
  • Pain
  • Proprioception
• What are the special senses that convey input to the CNS?

  • Smell
  • Taste
  • Vision
  • Hearing
  • Equilibrium
• What is the function of the motor division of the peripheral nervous system?

  • Conveys output from the CNS to effectors (muscles and glands)
• What are the two subdivisions of the motor division?

  • Somatic nervous system
  • Autonomic nervous system
• What does the somatic nervous system convey output to?

  Skeletal muscles only
• How are actions controlled in the somatic nervous system?

  Actions can be consciously controlled
• What does the autonomic nervous system convey output to?

  Smooth muscle, cardiac muscle, and glands
• How are actions controlled in the autonomic nervous system?

  Actions are not under conscious control
• What are the two main divisions of the autonomic nervous system?

  • Sympathetic division
  • Parasympathetic division
• What is the role of the sympathetic division of the autonomic nervous system?

  Helps support exercise and emergency actions (fight-or-flight)
• What is an example of the sympathetic division's action?

  Speeds up heart rate
• What is the role of the parasympathetic division of the autonomic nervous system?

  Helps support activities of rest and digestion
• What is an example of the parasympathetic division's action?

  Slows down heart rate
• What is the enteric plexus?

  • Extensive network of neurons in the digestive canal
  • Contains over 100 million neurons
  • Regulates activity of smooth muscle and glands of the digestive canal
  • Communicates with sympathetic and parasympathetic divisions of the ANS
  • Can function independently