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Central Nervous System

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Phrenology examination of the skull where bumps and indentations are used to ... [ laughter] But, you know, that's what they tell me at any rate. ... – PowerPoint PPT presentation

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Title: Central Nervous System


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The History of the study of the Brain
  • Early brain studies used the method of
    phrenology.
  • Phrenology examination of the skull where bumps
    and indentations are used to make a mental map
    and were then related to the character of that
    person.
  • The end of World War II and the massive quantity
    of brain injuries leads many people to examine
    the brain on a deeper level.
  • New technologies like the MRI have allowed
    doctors to observe the brain in operation in
    incredible detail.

http//skepdic.com/phren.html
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Overview The Nervous System
  • Central Nervous System (CNS) Brain Spinal
    Cord
  • Peripheral Nervous System Nerves to rest of
    body
  • Sensory nerves carry messages from the body to
    the brain
  • Motor nerves carry messages from the brain to the
    body

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Central Nervous System - Anatomy Function -
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The Human Spinal Cord
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The Spinal Cord
  • The main pathway for information connecting the
    brain and peripheral nervous system
  • - Conducts sensory information from the
    peripheral nervous system (both somatic and
    autonomic) to the brain.
  • - Conducts motor information from the brain
    to the various effectors (skeletal muscles,
    cardiac muscle, smooth muscle, glands).
  • Serves as a minor coordinating center responsible
    for some simple reflexes (e.g., withdrawal
    reflex).
  • The average spinal cord is 45 cm long in men and
    43 cm long in women. The spinal cord weighs
    approximately 35 g.

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The Spinal Cord Vertebrae
  • The human spinal cord is protected by the bony
    spinal column. The spinal column is made up of
    bones called vertebrae.
  • The spinal cord is located in the vertebral
    foramen and is made up of 30 segments 7
    cervical, 12 thoracic, 5 lumbar, 5 sacral and 1
    coccyx. A pair of spinal nerves exits from each
    segment of the spinal cord.

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  • The vertebral column provides structural support
    for the trunk and surrounds and protects the
    spinal cord.
  • The vertebral column also provides attachment
    points for the muscles of the back and ribs.
  • The vertebral disks serve as shock absorbers
    during activities such as walking, running, and
    jumping. They also allow the spine to flex and
    extend. Common injury Ruptured Disk

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Famous Spinal Cord Injuries
  • Mike Utley 1991 Detroit Lions Offensive Lion
    fractured his 6th and 7th cervical vertebrae.

http//www.mikeutley.org/images/mike.gif
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  • Christopher Reeves
  • Well, I totally decimated my first cervical
    vertebra and my second, and so my body and my
    spine and my head were not connected. Only my
    neck muscles were holding my head on, and
    fortunately I didn't suffer any brain damage, at
    least none that I can detect. laughter But, you
    know, that's what they tell me at any rate. But
    they literally had to put my head back on my
    body, and a wonderful surgeon, Dr. John Jane at
    the University of Virginia, was the one who
    operated on me, and they had to make it up. They
    had never done anything like this before, because
    this is what is called a hangman's injury, you
    know, like if you get dropped through the trap
    door and then cut down, sent to rehab and told to
    have a nice life.

http//record.wustl.edu/archive/2000/12-01-00/phot
os/reeves.jpg
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How does the brain protect itself?
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Four ways the brain protects itself
  • 1. Skull -
  • 2. Meninges
  • 3. Cerebrospinal Fluid
  • 4. Blood Brain Barrier (BBB)

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Central Nervous System- The Coverings of the
Brain (Shocks)
Meninges
  • Both the brain and the spinal cord are covered in
    three continuous sheets of connective tissue, the
    meninges.
  • The dura mater (the dura) the outer layer
  • The arachnoid the middle layer
  • The pia mater (the pia) the inner layer
  • The meninges PAD the brain

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http//www.baltimoresun.com/media/photo/2004-05/12
819309.jpg
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Central Nervous System- Cerebrospinal Fluid
(CSF) -
The entire surface of central nervous system is
bathed by a clear, colorless fluid, called
cerebrospinal fluid (CSF). The CSF is contained
within a system of fluid-filled cavities called
ventricles.
  • The total volume of CSF is 125-150 ml
  • Normal resting pressure of the CSF is between
    150-180 mmH2O.
  • Total production of CSF is about 400-500 ml/day
    (about 0.36 ml/min)

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Central Nervous System- Cerebrospinal Fluid
(CSF) -
  • What does the CSF do?
  • Protection The CSF protects the brain from
    damage by buffering the brain.
  • Buoyancy The pressure at the base of the brain
    is reduced by immersing in the CSF.
  • Excretion of waste products The one-way flow
    from the CSF to the blood takes potentially
    harmful metabolites, drugs and other substances
    away from the brain.
  • Endocrine medium for the brain The CSF serves to
    transport hormones to other areas of the brain.

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Central Nervous System - Blood-Brain Barrier
(BBB) -
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What is the Blood-Brain Barrier (BBB) ?
The barrier exists between the blood and the
brain
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BBB History
  • The late 19th century, Paul Ehrlichs experiment
    Certain dyes (e.g., a series of aniline
    derivatives) administered intravenously to small
    animals stained all the organs except the brain
    The brain has a lower affinity for the dye than
    the other tissues.
  • In 1913, Edwin G. Goldmans experiment
  • The dye trypan blue, directly injected into
    the cerebrospinal fluid of rabbits or dogs,
    readily stained the entire brain but did not
    enter the bloodstream to stain the other internal
    organs The CNS is separated from the blood by a
    barrier of some kind.

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BBB History
  • The late 1960s
  • Electron microscopy confirmed the hypothesis
    that brain capillaries provide the anatomical
    basis of the BBB
  • Recent studies
  • - The BBB is present in all vertebrate brains
  • - The BBB is laid down within the first 3
    months of human fetal life

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BBB FunctionNeuroprotective Role
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BBB Function
  • Physical Barrier
  • To protect the brain tissues from foreign
    substances or certain chemicals in the blood
    that may injure the brain

Biological Shield or Safeguard
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BBB FunctionNeuroprotective RoleObstacle
to Drug Delivery
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  • In order to cross the BBB in
    pharmacologically significant amounts, the
    therapeutic drugs must have the following
    characteristics
  • Lipid soluble
  • Have a molecular weight lt 400 Daltons
  • Not be a substrate for a BBB active efflux
    transporter

This class of drugs constitutes lt2 of all
potential small molecule drugs. Only few brain
disorders, such as depression, schizophrenia,
chronic pain, and epilepsy, respond to such
drugs. 100 of large molecule drugs and 98 of
small molecule drugs do not cross the BBB.
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Reflection
  • Of the four protective functions, which do you
    think would be most important in the field of
    psychology? Why?
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