Central tolerance

Examples of Central tolerance in the following topics:

• Maturation of T Cells

  • T cells belong to a group of white blood cells known as lymphocytes and play a central role in the cell-mediated branch of the adaptive immune system.
  • This process is an important component of central tolerance, a process that prevents the formation of self-reactive T cells that are capable of inducing autoimmune diseases in the host.
  • Autoimmune diseases reflect a loss of central tolerance in which the body's own B and T cells become sensitized towards self-antigens.

• Thymus

  • Central tolerance is another function of the thymus.
  • Autoimmune diseases occur when central tolerance is lost, which causes lymphocytes to recognize host molecules as antigens and attack them, even if those tissues otherwise function normally.

• Maturation of B Cells

  • In the bone marrow (the central lymphoid organ), central tolerance is produced.

• Analgesia: Relief from Pain

  • Analgesic drugs act in various ways on the peripheral and central nervous systems; they include paracetamol (para-acetylaminophenol, also known in the U.S. as acetaminophen), the non-steroidal anti-inflammatory drugs (NSAIDs) such as the salicylates (such as aspirin, shown in ), and opioid drugs such as morphine and opium.
  • The exact mechanism of action of paracetamol/acetaminophen is uncertain, but it appears to be acting centrally rather than peripherally (in the brain rather than in nerve endings).
  • Dosing of all opioids may be limited by opioid toxicity (confusion, respiratory depression, myoclonic jerks, and pinpoint pupils) and seizures (tramadol), but there is no dose ceiling in patients who accumulate tolerance.
  • When used appropriately, opioids and similar narcotic analgesics are otherwise safe and effective; however, risks such as addiction and the body becoming used to the drug (tolerance) can occur.
  • The effect of tolerance means that frequent use of the drug may result in its diminished effect so, when safe to do so, the dosage may need to be increased to maintain effectiveness.

• Specific T-Cell Roles

  • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
  • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.

• Life Functions

  • Organisms who live in an ecosystem must be able to survive its range of conditions, called the "range of tolerance. " Outside the range of tolerance are the "zones of physiological stress," where survival and reproduction are possible but not optimal.

• Lactose Intolerance

  • Those who are lactose intolerant can be more tolerant of traditionally-made yogurt than of milk because it contains lactase produced by the bacterial cultures used to make the yogurt.
  • However, those living among societies that are largely lactose-tolerant may find lactose intolerance troublesome.

• Antigens and Antigen Receptors

  • "Self" antigens are usually tolerated by the immune system; whereas "non-self" antigens can be identified as invaders and can be attacked by the immune system.
  • In order to keep the cytotoxic cells from killing cells just for presenting self-proteins, self-reactive T cells are deleted from the repertoire as a result of tolerance (also known as negative selection).
  • These antigens should, under normal conditions, not be the target of the immune system, but due to mainly genetic and environmental factors, the normal immunological tolerance for such an antigen has been lost.

• Flatfoot and Clawfoot

  • However, three military studies on asymptomatic adults suggest that persons with asymptomatic flat feet are at least as tolerant of foot stress as the population with various grades of arch.
  • However, three military studies on asymptomatic adults suggest that people with asymptomatic flat feet are at least as tolerant of foot stress as the population with various grades of arch.

• Grey and White Matter

  • The basic pattern of the CNS is a central cavity surrounded by gray matter made up of neuronal cell bodies external to which is the white matter which is made up of myelinated axons.
  • The basic pattern of the CNS is a central cavity surrounded by gray matter external to which is the white matter.
  • Gray matter is a major component of the central nervous system, consisting of neuronal cell bodies.  
  • A second major component of the central nervous system is white matter and it is composed of bundles of myelinated axons that connect various grey matter regions of the nervous system to each other and carry nerve impulses between neurons .
  • Distinguish between grey and white matter of the central nervous system