Immune System Facts Information and Function for Kids
2011-03-23 > Various
What is Immune System
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly.
Detection is complicated as pathogens can evolve rapidly, and adapt to avoid the immune system and allow the pathogens to successfully infect their hosts.
Immune System Function
The immune system is composed of many interdependent cell types that collectively protect the body from bacterial, parasitic, fungal, viral infections and from the growth of tumor cells. Many of these cell types have specialized functions. The cells of the immune system can engulf bacteria, kill parasites or tumor cells, or kill viral-infected cells. Often, these cells depend on the T helper subset for activation signals in the form of secretions formally known as cytokines, lymphokines, or more specifically interleukins.
The Organs of the Immune System
All the cells of the immune system are initially derived from the bone marrow.
In the thymus gland lymphoid cells undergo a process of maturation and education prior to release into the circulation. This process allows T cells to develop the important attribute known as self tolerance.
The spleen is an immunologic filter of the blood. It is made up of B cells, T cells, macrophages, dendritic cells, natural killer cells and red blood cells.
Lymph nodes are small bean shaped structures lying along the course of lymphatics. They are aggregated in particular sites such as the neck, axillae, groins and para-aortic region.
Killer T cell are a sub-group of T cells that kill cells that are infected with viruses (and other pathogens), or are otherwise damaged or dysfunctional. As with B cells, each type of T cell recognises a different antigen. Killer T cells are activated when their T cell receptor (TCR) binds to this specific antigen in a complex with the MHC Class I receptor of another cell. Recognition of this MHC:antigen complex is aided by a co-receptor on the T cell, called CD8. The T cell then travels throughout the body in search of cells where the MHC I receptors bear this antigen. When an activated T cell contacts such cells, it releases cytotoxins, such as perforin, which form pores in the target cell's plasma membrane, allowing ions, water and toxins to enter. The entry of another toxin called granulysin (a protease) induces the target cell to undergo apoptosis. T cell killing of host cells is particularly important in preventing the replication of viruses. T cell activation is tightly controlled and generally requires a very strong MHC/antigen activation signal, or additional activation signals provided by "helper" T cells.
Macrocytic Anemia Causes and Treatment Anemias that are associated with macrocytosis (a mean corpuscular volume of >100 fL) include those from liver disease, alcoholism, hypothyroidism, certain drug exposures, megaloblastic anemia, myelodysplasias, preleukemia, or those with marked reticulocytosis due to the larger size of the young erythrocytes.
Candida albicans Causes, Those at Risk, Symptoms and Treatment Candida albicans is a fungus that is normally present on the skin and on membranes of the mouth, throat, intestines, and vagina. It becomes an infecting agent only when there is some change in the body environment that allows it to grow out of control.
Radiation Safety Principles and Standard
The International Commission on Radiological Protection (ICRP) has
proposed that following principles should guide the use of ionizing
radiation safety standard:
No practice involving exposures to radiation should be adopted unless it
produces sufficient benefit to the exposed individuals or society to offset
the radiation detriment it causes (the justification of practice)
In relation to any particular source within a practice, the magnitude of
individuals doses, the number of people exposed, and the likelihood on
incurring exposures where these are not certain to be received should all kept
as low as reasonably achievable (ALARA), economic and social factors being
taken into account. This procedure should be constrained by restrictions of
the doses to individuals (dose constraint), so as to limit the inequity likely
to result from the inherent economic and social judgments.
The exposure of individuals resulting from the combination of all the
relevant practices should be subject to dose limits, or to some control of
risk in the case of potential exposures. These are aimed at ensuring that no
individual is exposed radiation risks that are judged to be unacceptable from
these practices in any normal circumstances. Not all sources are susceptible
of control by action at the source and it is necessary to specify the sources
to be included as relevant before selecting a dose limit.
Hiatus Hernia Treatment The term hiatus hernia describes diaphragmatic hernia or weakness in the diaphragm, the horizontal muscular wall separating the organs of the chest from the organs of the abdomen. A hernia is an abnormal protrusion of an organ or tissue through an opening. A hiatus, or opening, permits the esophagus to carry food from the mouth to the stomach. Blood vessels and nerves also pass through the diaphragm. The diaphragm is an important group of muscles for contracting and expanding the lungs, forcing air in and out of the lung tissues.
Smoking effects for reproduction of women In all of its dimensions the reproductive process is impaired by the use of tobacco, particularly cigarette smoking. Problems can be found in association with infertility, problem pregnancy, breastfeeding, and the health of the new born.
Kidney Stones Causes, Symptoms and Treatment Kidney stones are deposits of mineral or organic substances that form in the kidneys. When abnormally high levels of certain minerals, such as calcium, are in the urine, they may condense into hard masses, forming stones in the kidney or urinary tract. The stones may be as small as a tiny pebble or as large as a walnut.
Risk Reduction for Developing Cancer Because cancer will probably continue to be the second most common cause of death among adults, it is important for you to explore ways of reducing your risk of developing cancer. The following factors, which could make you vulnerable to cancer, can be controlled or at least recognized.
Mesenteric Ischemia Mesenteric ischemia is classified as acute mesenteric ischemia (AMI) chronic mesenteric ischemia (CMI). AMI is subdivided into occlusive and nonocclusive mesenteric ischemia. Occlusive mesenteric ischemia results from either thrombotic or embolic arterial or venous occlusion. Approximately 80% of cases of AMI are occlusive in etiology, with arterial emboli or thromboses in 65% of cases and venous thrombosis in 15%. Arterial occlusions result from emboli in 75% of patients and in situ thrombosis cause the remaining 25%. NOMI is caused by low perfusion states and is responsible for 20% of AMI.
Pigment Disorders and Birthmarks The mechanism that controls skin coloration is described above under “Skin Color.” Abnormalities in the creation and distribution of melanin result in the following disorders some of which are negligible.
These are small spots of brown pigment that frequently occur when fair-skinned people are exposed to the sun or to ultraviolet light. For those whose skin gets red rather than tan during such exposure, freckles are a protective device. In most cases, they recede in cold weather. A heavy freckle formation that is permanent can be covered somewhat by cosmetic preparations. No attempt should be made to remove freckles with commercial creams or solutions unless supervised by a physician
Ambiguous Genitalia Wiki, causes and pictures Are you looking for ambiguous genitalia wiki and pictures? The first concept that an examiner might want to know if they were asking the question - or if you were approached with the clinical thing - is that there are many different levels of sex, and not just chromosomes. We all tend to focus on chromosomes but that’s just one. Gonads, ovaries or testes? What are the internal ducts? What do the external genitals look like? What is the hormonal sex; androgen or estrogen circulating? And what is the psychosocial sex? All these things must be consistent in order to have a successful outcome of sex assignment.
What is a Low Glycemic Diet A recent Harvard study found that a low-glycemic diet was the best of three popular diets at both maintaining metabolism during weight loss and maintaining cardiovascular health. But what is it and what are low glycemic foods anyway?
The diet, which is also known as the glycemic index diet or GI diet, emphasizes unprocessed foods, complex carbs and food combining. It was originally developed as a diet to help diabetes patients regulate their blood sugar and, according to WebMD, is still most effective in this capacity. Many popular diets, including Nutrisystem, the Zone diet, Sugar Busters and South Beach diet incorporate low-glycemic principles.
Heat Stroke Prevention Tips Each summer we hear about athletes suffering serious heat illness, particularly heat stroke, during recreational running events, marathons and fun runs. In order to prevent becoming a statistic, it's helpful to learn about the most common types of heat illness and take precautions if you exercise in hot weather. Here is some tips for heat stroke prevention.
Cyclosporin As we move on, drugs like CellCept and Prograf are replacing cyclosporin, but cyclosporin can take a normal person and give him tophaceous gout in about 24 months. Because it is a causer of renal insufficiency it also inhibits the secretion of uric acid by the kidney and resorption from uric acids, so it is a three-fold toxin in terms of developing gout in patients. It can develop raging tophaceous gout, and one of the problems was is that most patients with renal and heart transplant were on drugs such as Imuran and Cyclosporin, and Allopurinol interact with one another. You have a real difficult time of using Allopurinol on a patient and Azathioprine because of drug interactions and toxicities. These individuals are difficult to treat. Rapid in onset and have severe tophaceous gout.