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.
Actinic Keratosis Pictures, Causes and Treatment Actinic keratosis (senile or solar keratosis) is the most common precancerous dermatosis.
Single or multiple lesions develop on areas exposed to the sun, such as the face, the backs of
the hands, the forearms, the neck, and balding scalp. Actinic cheilitis denotes scaly or
crusted patches of precancer on the vermilion of the lips. In actinic keratosis, lesions are
round or irregularly shaped, erythematous or tan plaques with an adherent scaly or rough
surface. They range in size from several millimeters to 1 cm or more.
Locally invasive lesions
have been reported to develop in 12 percent of patients with actinic keratoses. These lesions
result in squamous cell carcinomas that occasionally metastasize [see Malignant Epithelial
Tumors, Squamous Cell Carcinoma, below].1,14 Signs that an actinic keratosis has become
malignant are elevation, ulceration or inflammation, and recent enlargement, usually to a
diameter greater than 1 cm.
Breast Cancer Treatment and Therapy Guidelines What about the follow-up after our primary and adjuvant treatment for breast cancer? We know from many good signs that most of the recurrences are found by patients, second most by physicians and almost never by routine tests. Therefore, the official recommendations for follow-up of asymptomatic individuals after primary therapy is that they have history and physicals about every four to six months and that they have annual mammographies. There are no films, scans, tumor markers that are indicated in the follow-up of asymptomatic individuals. So, we usually suggest a history and physical every three to six months and an annual mammography. This is something that is continually under review. It might change, but today, all of the studies that have been done have never been able to show survival benefit for intensive screening with radiographic and blood testing as opposed to just clinical follow-up of these patients.
Metastatic breast cancer. If breast cancer is found to have spread at the time of diagnosis or recurs later after local therapy, we have a situation which cannot be realistically considered to be a curable disease at this point. I think that is important. It is equally important however to recognize that the survival ratio with metastatic breast cancer is very, very variable. If you have metastatic lung cancer or inoperable pancreas cancer, most of these patients are dead in year. Certainly within 18 months. There is almost no survival at two years with a disease like that. Breast cancer is all over the board. The median survival from onset of metastases is probably on the order of two to three years but all of us have patients who have lived 10 years or more in very good physical condition after the development of metastatic disease. So, again looking at the clinical parameters of what the disease-free interval is, what sites are involved, whether the hormone receptors are positive, can help you project somewhat what is going to happen but is a situation with an extremely variable prognosis.
Prescription diet pills list and review Prescription diet pills aren't for the person who wants to shed a few pounds to fit into a holiday party dress or tuxedo. Only people who are "obese" (those who are 30 percent over their ideal weight, or have a Body Mass Index (BMI) of 30 or more - see National Heart, Lung and Blood Institute: Healthy Weight to calculate your BMI) or who have a history of high blood pressure or diabetes are good candidates for prescription diet medications, according to the National Institutes of Health (NIH).
Angina Pectoris Causes The most common symptom of coronary artery disease is angina pectoris, chest pain caused by insufficient oxygen getting to the muscles of the heart. Angina is usually described as a tightness, pressure, or dull aching pain under the breastbone and on the left side of the chest. Often it is described as "feeling like someone's sitting on my chest." The pain may radiate from the chest to the left arm or the left side of the jaw, and occasionally to the back.
The symptoms of angina are experienced in different ways by different people, but an individual usually experiences the same symptoms every time an attack occurs. Many experience sweating, shortness of breath, chills, or nausea during an attack. Others have no symptoms but a mild chest discomfort. Angina usually resolves five to ten minutes after exertion stops.
Teenage Acne Treatment Girls Are you looking for teenage acne treatment for girls? Acne is caused when a hair follicle get clogged with an oil called sebum and skin cells. Skin bacteria thrive and multiply in sebum, causing inflammation. Some acne consists of simple blackheads and whiteheads. Inflammation within the pore causes a pimple (also called a “papule”) or a pus-filled pimple (“pustule”), depending on how deep it is. If it’s really deep, it can cause a painful cyst and scarring.
Women and Cardiovascular Disease Heart disease is the number one killer of both men and women. In the United States, heart attacks kill about 240,000 women a year; stroke takes another 88,000 women’s lives. That compares with about 43,000 women who die annually from breast cancer. In fact, nearly twice as many women die of CVD (Cardiovascular Disease) than all cancers combined.
While men do have more heart attacks and have them earlier in life, women have a much lower chance of surviving a heart attack. We understand the mechanism that cause CVD in men from years of male-oriented research. But only within the last decade have we moved toward a better understanding of how CVD manifests itself in women.
Symptoms of Salmonella infection Salmonella infection is a common bacterial disease that affects the intestinal tract. Salmonella bacteria typically live in animal and human intestines and are shed through feces. Humans become infected most frequently through contaminated water or food sources. So what are symptoms of Salmonella infection?
Beta carotene foods and benefits (provitamin A) Vitamin A comes in several forms, such as preformed retinoids found in animal products that are ready for use by the body and carotenoids found in plants. Carotenoids are called provitamin A because they must first be converted to the retinoid form if they are to be used for vitamin A functions. More than 600 carotenoids are found in nature; 50 of them have potential vitamin A activity. The most potent form is beta-carotene. The retinoids and carotenoids combine to form what is generally referred to as vitamin A.
Leprosy Symptoms, Causes and Treatment More than 10 million people are victims of leprosy, an infectious disorder also known as Hansen’s disease. Although leprosy is more common in tropical regions, where up to 10 percent of some population groups may be affected, the disease also occurs in several northern countries, including the United States, where the disease is found in coastal states from California through Texas and Louisiana, and from Florida to New York. Ancient medical writings indicate that leprosy was known in China and India about 3,000 years ago but did not spread to the eastern Mediterranean until A.D. 500 or 600.
Chronic Hives in Children Hives are harmless skin allergic reactions which might irritate a child a great deal. They appear as raised pale or red colored skin welts. Hives may also appear as mosquito bites that keep changing their shapes and even their locations. Hives in kids are generally found on arms, legs, back and torso. Children may find the itching associated with hives quite unbearable!
Ornish diet recipes and meal plan Are you looking for Ornish diet recipes and meal plan? Unlike other diet books that make big promises, Eat More, Weigh Less, by Dean Ornish, MD, soft-pedals the health claims for this diet for the masses, adapted from his regimen to reverse heart disease. Ornish is well known in the medical community because of his success in reversing blockages to the heart, once thought impossible without surgery or drugs. Ornish also runs his own health and diet site here at WebMD which can give you additional details about his plan.
HCG Diet Plan Phase 2 Are you looking for HCG Diet Plan Phase 2? HCG stands for Human Chronicle Gonadotropin hormone which helps lose weight. This is an effective approach used by most women today. HCG diet plan is a kind of program that promises to help you lose 1 pound daily with the help of a proper diet meal plan. On the other hand, a diet meal plan should be strictly followed to ensure an efficient result.
Blood Pressure Definition Classification and Measurement Devices Blood pressure definition
Blood pressure (BP) is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. During each heartbeat, BP varies between a maximum (systolic) and a minimum (diastolic) pressure. The mean BP, due to pumping by the heart and resistance to flow in blood vessels, decreases as the circulating blood moves away from the heart through arteries.