brain barrier systems

• blood brain barrier


  Tightly packed blood vessels creating a barrier which allows certain molecules to pass through 

  • Protects the neural tissue from variations in blood composition and toxins 
  • Hormones can pass through 
• skull


  the brain is encased in bone
• meninges

  3 layers of membrane

  dura - tough, inelastic bag that surrounds brain and spinal cord

  arachnoid membrane - spider web like

  Pia matter - thin and close to the surface of the brain
• cerebrospinal fluid


  Buoyancy - allows the brain to maintain its density without being impaired by its own weight

  • Protects the brain tissue from injury when hit or jolted
  • Allows for homeostatic regulation 
  • Hydrocephalus 
  • CSF puts pressure on the brain 
  • Usually in infancy
  • Can be acquired after a head injury or brain cancer