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