The Nervous System Images with permission of Eric Chudler <[e-mail]> Check out his site it is awesome!

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The Nervous SystemImages with permission of
Eric Chudler ltchudler_at_u.washington.edugtCheck out
his site it is awesome!
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Nerve tissues respond to stimuli and are composed
of individual cells called neurons and their
associated support cells.
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Nerve cells can measure up to two meters in
length and are well suited to transmitting
messages. These cells convert stimuli into
electrochemical impulses and transmit the signals
down their lengths.
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Neuron Structure
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• Sensory neurons from receptor cells, receive a
  stimulus
• Motor neurons from effector cells, respond to a
  stimulus.
• Interneurons are between sensory and motorneurons.

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The Action Potential is an all or none response,
there is an AP or not! Web site explanation.
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The Action Potential moves down the neuron from
dendrite to axon then to the end brush or
presynaptic terminal.

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The Action Potential explanation!
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A gap called the synaptic cleft separates the
presynaptic membrane from the postsynaptic
membrane (dendrite or target cell)
The synapse is the means by which an impulse is
transmitted between neural cells.
The axon of one neuron synapses with the
dendrites of other neurons.
Transmitters move across the synapse to send
messages from one neuron to the other. Receptor
molecules pick up the message.
See pg 703
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The transmission of nerve impulses can be altered
by various substances. Stimulants like caffeine
can increase the amount of transmitters released
across the synapse.
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Brain and Spinal Cord
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Brain and Spinal Cord ProtectionThere are 3
membranes protecting the brain and spinal cord -
meninges. The spaces between the membranes are
filled with cerebrospinal fluid. The fluid
cushions the brain and spinal cord against shock
and removes wastes to the blood.
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Stroke!

• A stroke occurs when the blood supply to the
  brain is cut off by a broken or blocked blood
  vessel.
• Damage to the tissue of the area effected results
  from lack of fresh oxygenated blood.
• Damage to the right side of the brain effects the
  left side of the body!

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• Spinal Cord Damage
• Damage to the cord results in loss of ability to
  use body parts below the injury.
• Little or no sensation occurs in effected body
  parts.

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• Medical Technology
• EEG - uses electrical impulses produced by the
  brain to show brain activity
• CAT scan - produces a 3-D image using X - rays
  and a computer. This can be used to reveal
  disorders like tumors, broken blood vessels and
  other brain problems (reduces the need to open up
  people's heads!)

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• Medical Technology
• MRI - This machine uses magnetic fields to excite
  hydrogen atoms inside your body. Since tumors
  are different than your body tissues they show up
  on the MRI image (they are denser). These images
  are also in 3-D.

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Alzheimers

• An illness that shows up in the elderly portions
  of out population.
• Complications include loss of nerve cells from
  cerebral cortex, neurofibrilar tangles, neuritic
  plaques and changes in enzyme systems in the
  synapse.
• This results in low levels of transmitters and
  fewer neurons to transmit messages

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Epilepsy

• A type of Brain disease that can result in sudden
  loss of conciousness.
• Caused by non-functioning cells in the brain that
  can lead to seizures.
• Usually the seizures are triggered by something
  and a warning message such as a smell precedes
  the event.
• Do not place an object in the mouth of the victim.

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• Peripheral Nervous System - all neurons lying
  outside that brain and spinal cord. It includes
  that 12 cranial nerves and 31 pairs of spinal
  nerves. Cranial nerves are important for the face
  and senses while the spinal nerves are useful in
  reflexes and somatic control.

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Somatic Nervous System

• This system is under conscious control through
  motor neurons connected to your skeletal muscle.
• Through the use of this system you can control
  all voluntary actions.

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Autonomic Nervous System

• This system is NOT under conscious control and
  involves nerves that connect to glands, smooth
  muscle and cardiac muscle. This system has two
  major components, one that stimulates the body
  "sympathetic" and one that slows the body down,
  "parasympathetic". The ganglia for these systems
  are located next to the spinal cord.

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