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.
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.
US judge blocks graphic warning on cigarette U.S. District Judge Richard Leon, in a 29-page ruling Monday, granted the preliminary injunction because he believed there was a "substantial likelihood" the cigarette companies ultimately would win "on the merits of their position that these mandatory graphic images unconstitutionally compel speech."
Personal Health Care Plan Your personal involvement in your own wellness is critical. Taking a proactive approach to practicing preventive behaviors can go along way toward giving you a long and healthy life. Sometimes, however, regardless of the steps you take to care for yourself, you still get sick. At such a time, it is important that you continue to be actively involved in your care. The more you know about your own body and about factors that can affect your health, the better able you will be to communicate complete information to your doctor. It also helps you to make informed decisions and to recognize when a certain treatment may not be right for you.
Cerebral palsy types, symptoms and treatment Cerebral palsy (CP) is a general term to describe various disorders of muscle control caused by a period of lack of oxygen to the brain.
Cerebral palsy Causes
Cerebral palsy is caused by brain or nerve damage that usually occurs before or around the time of birth. The damage may result when brain tissue becomes starved for oxygen for any reason. It may result from separation and bleeding of the placenta (the organ that anchors the fetus to the wall of the uterus and provides nourishment) in late pregnancy or form disorders caused by diabetes in the mother. It is characteristic of cerebral palsy that the neurologic problems are not progressive.
Pulmonary Embolism Symptoms and Prevention Pulmonary embolism is a condition in which a part of blood clot in a vein breaks away and travels through the heart and into the pulmonary circulatory system. Here the vessels leading from the heart branch like a tree, gradually becoming smaller until finally they form capillaries, the smallest blood vessels. Depending on its size, the clot will at some point reach a vessel through which it cannot pass, and there will lodge itself. The clot disrupts the blood supply to the area supplied by that vessel. The larger the clot, the greater is the area of lung that loses its blood supply, and the more drastic the results to the patient.
Malaria Symptoms and Treatment Malaria, one of the common diseases in the world, gets its name from the Italian word for “bad air” because of an ancient belief that a mysterious substance in the air was the cause of the ailment. It is now known that the disease is caused by any of at least four parasites carried by Anopheles mosquitoes. According to the World Health Organization (WHO), malaria causes more than 300 million acute illnesses and at least one million deaths annually. Ninety percent of deaths due to malaria occur in Africa, mostly among young children. The disease was relatively rare in United States until the 1960s, when hundreds of cases began to appear among military personnel who apparently contracted the disease in south east Asia but did not develop symptom until they returned to the United States. The disease later occurred in soldiers who had never left the United States. It was apparently transmitted by domestic Anopheles mosquitoes that had become infested with the malaria parasites.
Kegel Exercises for Women, Benefits and Instruction Are you looking for instruction and benefits Kegel Exercises for Women? A pelvic floor exercise, more commonly called a Kegel exercise (named after Dr. Arnold Kegel), consists of contracting and relaxing the muscles that form part of the pelvic floor, which are now sometimes colloquially referred to as the "Kegel muscles". Several tools exist to help with these exercises, though many are ineffective. Exercises are usually done to reduce urinary incontinence and aid with childbirth in women, and reduce premature ejaculatory occurrences in men, as well as increase the size and intensity of erections.
Erythema Multiforme and Stevens Johnson Syndrome Erythema multiforme (EM) is an acute hypersensitivity reaction characterized by distinctive skin lesions and mucous membrane involvement that has a spectrum of severity. It occurs in two forms: the more common "minor" type and the more severe "major" type, also called Stevens-Johnson syndrome (SJS). Sometimes EM includes toxic epidermal necrolysis (TEN) or Lyell disease. EM minor first was described completely by von Hebra in 1866; Stevens and Johnson described the major variant in 1922. EM occurs more often in males, and 20% to 50% of cases occur in the pediatric age group, although rarely in those younger than age 3 years. A winter predominance is suggested.
The pathologic process responsible for EM is unknown. A review of the literature generates an extensive list of causative or inciting agents. Most frequently mentioned are sulfonamide antibiotics and anticonvulsants, both used commonly in pediatric practice. Malignancies, radiotherapy, autoimmune diseases, and infectious agents such as mycoplasma also have been implicated as possible causes. In 1992, Weston et al described a high incidence of herpes simplex virus (HSV) in EM lesions among both adults and children with or without a preceding history of HSV infection.
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Talking with Your Doctor about Cancer Diagnosis Anytime there is suspicion of cancer, the person involved is likely to react with great anxiety, fear, and anger. Emotional distress is sometimes so intense that the person involved is unable to severe as his or he own best advocate in making critical health-care decisions. If you find it difficult to know what to ask your doctor on a routine exam, imagine how hard it would be to discuss life or death options for yourself or loved one. Having a list of important questions to ask when you appear at the doctor’s office may help tremendously. Remember, your health-care provider should be your partner in making the best decisions for you. By actively challenging, questioning, and letting the physician know your wishes, difficult decisions may become easier.
Symptoms of pneumonia in adults Are you looking for symptoms of pneumonia in adults?
Pneumonia is a general term that refers to an infection of the lungs, which can be caused by a variety of microorganisms, including viruses, bacteria, fungi, and parasites.
Most cases of pneumonia are caused by viruses, including adenoviruses, rhinovirus, influenza virus (flu), respiratory syncytial virus (RSV), and parainfluenza virus (which causes croup).
Types of Schizophrenia and Symptoms Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social or occupational dysfunction. The onset of symptoms typically occurs in young adulthood, with a global lifetime prevalence of about 0.3–0.7%. Diagnosis is based on observed behavior and the patient's reported experiences.
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