12.1

• Central Nervous System (CNS)

  brain and spinal cord ONLY

  nervous tissue, connective tissue, and blood vessels

  process and coordinate sensory from inside and outside the body

  motor commands control activities of peripheral organs

  other functions = intelligence, memory, learning, emotion
• Peripheral Nervous System (PNS)

  all nervous tissue outside of CNS and ENS

  delivers sensory information to CNS

  carries motor commands to peripheral tissues

  nerves (peripheral nerves)

  axon bundles and connective tissue and blood vessels

  carry sensory information and motor commands

  cranial nerves = brain

  spinal nerves = spinal cord
• afferent division

  carries sensory information

  receptors in peripheral tissues/organs = CNS
• efferent division

  carries motor commands

  CNS = muscles/glands/adipose tissue
• somatic nervous system (SNS)

  controls skeletal muscle contractions

  voluntary and involuntary (reflexes)
• autonomic nervous system (ANS)

  controls subconscious actions, contractions of smooth and cardiac tissue, and glandular secretions

  sympathetic division = stimulating effect

  parasympathetic division = relaxing effect
• enteric nervous system (ENS)

  100 million neurons in walls of digestive tract

  initiates coordinates visceral reflexes locally

  no CNS instructions