Ch 3

  1. Brain Protection and Support
    1. Cranium - made up of 8 skull bones that are fused together along zig-zag joints called sutures; brain fits into the cranial cavity

    2. Meninges - three layers of protective tissue that provide a tough outer protection to the brain and spinal cord

    3. Cerebrospinal Fluid (CSF) - clear fluid that buffers the brain and spinal cord from shock
  2. Brain Protection and Support (cont.)
    4. Blood and Oxygen Supply - delivered to brain through the bloodstream

    5. Blood-Brain Barrier - glial cells form a protective covering around blood vessels to prevent toxic substances from entering the brain
  3. Meninges, Layer #1
    Dura Mater ("hard mother"); tough, leather-like outer layer; pain sensitive

    Long channels ("sinuses") serve as veins and drain used blood and CSF
  4. Meninges, Layer #2

    Looks similar to a spider web

    Separated from Dura mater by the tiny, fluid-filled sub-dural space
  5. Meninges, Layer #3
    Pia Mater ("soft mother"); barely visible, close to brain and spinal cord; its many blood vessels carry oxygen and nutrients to the CNS and plays a key role in removal of waste products

    Separated from the Arachnoid by the sub-arachnoid space
  6. Cerebrospinal Fluid (CSF)
    Clear, colorless fluid that buffers the brain and spinal cord from shock; circulates constantly between subarachoid space and ventricles (4 large brain cavities)

    Ventricle walls form a network of capillaries called the choroid plexus, which is covered in glial that produce 3/4 liter of CSF per day from blood plasma
  7. Functions of CSF
    1. Provides protective cushion

    2. Protects against injury

    3. Diffuses waste material

    4. Maintains a "special environment" for the brain

    5. Penetrates between brain cells to deliver nutrients, hormones, and neurotransmitters
  8. Brain Nourishment
    Brain requires at least 20% of the body's energy

    Neurons cannot store energy, and are very particular about what they can use as energy - only glucose

    Glucose is delivered by blood to the brain; if the bloodflow is cut off for as little as 3 minutes, neurons begin to die and permanent damage can occur
  9. Blood-Brain Barrier (BBB)
    1. Protects the Brain: works as a filter by tightly sealing capillaries, overlapping the cells that form the capillaries, and by special glial cells that surround walls

    2. Neurotransmitters: unable to pass through BBB, so must rely on substances than can

    3. Neurotoxins: more than 440 harmful substances can pass through BBB
  10. Ischemic Strokes
    Most common

    Occurs when blood supply to part of the brain is blocked
  11. Types of Blood Clots
    Cerebral thombosis: blood clot forms in a cerebral blood vessel and blocks blood flow

    Cerebral embolism: an embolus ("wandering" blood clot) travels from the heart/arteries to the small vessels of the brain and creates a sudden blockage

    Transient ischemic attack ("mini-stroke"): temporary blockage of blood flow to part of the brain
  12. Hemorrhagic Strokes
    Most common type = anerurysm; occurs when an artery in the brain leaks or ruptures; can be caused when a wakened or diseased spot in the wall of an artery/vessel bursts
Card Set
Ch 3
Psyc 4, Quiz 1, Ch 3