04. Peripheral Nervous System

• Peripheral Nervous System

  • This second part of the Nervous System consists of cranial, spinal, and peripheral nerves.
  • Cranial nerves have 12 pairs of motor and sensory nerves from the brain.
  • Spinal nerves have 31 pairs of motor and sensory nerves from the spinal cord.
  • Peripheral nerves are located outside the brain and spinal cord.
• 3 Major Functions of the Peripheral Nervous System

  • Conveying motor commands to all voluntary striated muscles in the body
  • Carrying sensory information about the external world and the body to the brain and spinal cord.
  • Regulating autonomic functions such as blood pressure and sweating.
• Autonomic Nervous System

  • There are 2 subdivisions: 
  • Sympathetic nervous system becomes dominant in times of fear.
  • Parasympathetic nervous system returns your body to its normal state.
• Sympathetic

  • You are startled and experience fear.
  • Nerve impulses make your heartbeat faster and cause your blood pressure to rise.
• Parasympathetic

  • PSN releases acetylcholine to dilate blood vessels and slow down heart rate.
  • Your body returns to its normal state.