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AP PSYCH 2.3 Overview of the Nervous System and the Neuron

The Nervous System

  • The nervous system is made up of two parts
  • The Central Nervous System (CNS) includes the brain and spinal cord
  • The Peripheral Nervous System contains two subtypes: The Somatic Nervous System and Autonomic Nervous System
    • The Autonomic Nervous System is further divided up into the Sympathetic Nervous System and the Parasympathetic Nervous System

The CNS

  • The brain communicates and coordinates the actions between other parts of the body
  • It organizes movements, creates thoughts, forms emotions, and produces behaviors

The Brain

  • The brain received support and protection from other parts of the body
    • It weighs around three pounds, and is 2-3% of your body weight
    • Nutrients and oxygen are carried by blood vessels
    • It is protected by the bones of the skull and hard membranes attached to it
    • Fluid also surrounds the brain, which acts as a chock absorber

The Spinal Cord

  • This is the “backbone” of the CNS, for lack of a better word
    • It transmits messages from the brain to the muscles and glands
    • It extends from the brain down the back
    • It consists of several columns of nerves about as thick as a thumb
    • It is protected by bones of the spine called vertebrae
    • Spinal reflex is a simple, automatic response to something

PNS

  • The PNS is a bundle of nerves outside of the CNS which transmits information between the brain and the rest of the body
  • The PNS’ primary function is to carry out the orders from the CNA
  • Within this one system, there are two other systems, Somatic and Autonomic

Somatic Nervous System

  • The somatic nervous system is a system of sensory nerves which controls voluntary movement of the skeletal muscles
  • This system also includes the sensory nervous system and the somatosensory organs
    • These convey sensory information from skin and muscle such as touch, pain, and temperature to the CNS

Autonomic Nervous System

  • The autonomic nervous system is the involuntary system in humans
  • We do not think about the systems that the ANS controls unless there is a problem or it is specifically brought to your attention
    • For example, breathing, heart beating, digestion, and many other areas of daily functioning are controlled by the ANS
  • This system has two divisions that work together during a perceived emergency
    • The Sympathetic Nervous System is the emergency response system which allows one to response to situations which require alertness
    • The Parasympathetic Nervous System functions to calm you down and allows one to relax after an emergency has occurred
    • This is why you may not feel any pain during a period of high energy, but after you calm down, you will start to feel the injuries