Transcript Sleep
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 2 • 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 3 • 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. 4