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Immune System
• Body Defenses
* Immune System is our first Line of defense
against malicious Invaders
* These Invaders, Viruses, Bacteria and Yeast,
Range from Common and Mild, such as all
too familiar cold, to severe and life
threatening, e.g. HIV, Meningitis or
Tuberculosis
* Activation of Immune System Triggers Cells
- Leucocytes, Macrophages, Acute Phase Proteins
→ Travel to Site of Attack, to Identify, Kill and the remove Invading Pathogens
→ Responses helps to Combat Infection, Conserve Energy and Aid Repair, but
when activated too much or for too long they can be very Damaging
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• Brain and Defense Responses
* Brain exhibits Array of local Immune and Inflammatory Responses, and
indeed is important Controller of Immune System and of acute phase responses
* The most important Signals are Group of proteins which came to light only
in the last 20 years - known as Cytokines
• Cytokines as Defense Molecules
* Cytokines are normally produced in Body at very low Levels, but are switched
on quickly in response to Disease or Injury(Cytokines include: Interferons,
Interleukins, Tumour necrosis Factors and Chemokines)
* Cytokines enter Blood Stream where they send Signals to distant Organs
Including Brain
* Important Regulator of Cytokines Production is Brain that, through Neural
Signals to Tissues or Hormones, can switch Cytokines on or off
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• Stress and Immune System
* Precise Mechanisms responsible for Link between Stress and Immune
system are not fully worked out, but we do know that important Feature is
activation of the hypothalamic-pituitary-adrenal axis
* One of main responses to Stress in Brain is increased Production of Protein
in Hypothalamus called Corticotrophin Releasing Factor(CRF)
- CRF: Pituitary Gland → Hypothalamus(Short Distance), to release another Hormone,
Adrenocotrophin Releasing Factor(ACTH)
• Immune and Inflammatory responses within Brain
* Cytokines are active contributors to Brain Diseases
→ Brain Disease seems that over Production of Molecules within Brain itself can
Damage Neurons - Particularly
→ Multiple Sclerosis, Stroke and Alzheimer's, etc.
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