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.
Bunion surgery recovery and photos Are you looking for Bunion surgery recovery and photos? Bunion surgery generally involves an incision in the top or side of the big toe joint and the removal or realignment of soft tissue and bone. This is done to relieve pain and restore normal alignment to the joint. If the joint is severely deformed, it may be stabilized with tiny wires, stitches, screws, or plates. There are no guarantees that a bunion surgery will fully relieve your pain.
Over the counter ringworm treatment for kids Are you looking for over the counter ringworm treatment for kids? What will you do if you see red itchy patches on your body? It may be a case of ring worm infection. It may sound bad, but it can be cured easily with over-the-counter ringworm treatment.
Ringworm is a common skin infection caused by a fungus. The fungi feeds on the dead cells of skin and hair causing a ring of irritated itchy skin that looks like a worm. This may cause a rash and becomes sore. It may appear as scalp ring worm, body ringworm, face ring worm or groin ringworm.
Iron deficiency symptoms eyes Are you looking for iron deficiency symptoms eyes? Iron deficiency (sideropenia or hypoferremia) is one of the most common of the nutritional deficiencies. Iron is present in all cells in the human body, and has several vital functions. Examples include as a carrier of oxygen to the tissues from the lungs in the form of hemoglobin, as a transport medium for electrons within the cells in the form of cytochromes, and as an integral part of enzyme reactions in various tissues. Too little iron can interfere with these vital functions and lead to morbidity and death.
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.
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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.
Symptoms of Pregnancy On the chart below are list of the most common symptoms of pregnancy and what they mean. You can also click the sign to get more information on each symptoms of pregnancy. The three categories of pregnancy symptoms are: possible, probable and positive.
What is the Best Treatment for Acne Scars Acne scar treatments have had a long and complicated history. Traditionally, the most famous method for getting rid of the scars left behind by acne was a harsh process known as "dermabrasion."
Now if you've never heard of dermabrasion, let me put this into perspective for you. "Derm" comes from the Greek word "Dermis", which means skin. "Abrasion" is the process of wearing down or rubbing away by means of friction. Put the two together and what do you get? Dermabrasion.
Gallbladder diet after surgery Are you looking for gallbladder diet after surgery?
Most people never give a thought to the health of their gallbladder. The pear-shaped organ does have an important job, collecting and storing bile the fluid that helps the body digest fats. But unlike the heart, liver, and kidneys, the gallbladder isn't necessary to keep the body healthy and functioning. Even when it isn't working as well as it should and gallstones develop, most people are unaware that there is a problem.
Yet in a small percentage of people, gallstones can trigger a variety of symptoms, such as abdominal pain, bloating, gas, nausea, and vomiting. When gallstone symptoms are especially uncomfortable, the typical treatment is surgery.
Spinal Stenosis Definition and Treatment What is defintion of Spinal Stenosis. Spinal stenosis is a narrowing of one or more areas in your spine — most often in your neck or lower back. This narrowing can put pressure on the spinal cord or spinal nerves at the level of compression. Stenoses of the vascular type are often associated with unusual blood sounds resulting from turbulent flow over the narrowed blood vessel. This sound can be made audible by a stethoscope, but diagnosis is generally made or confirmed with some form of medical imaging.
aortic stenosis (AS) a narrowing of the aortic orifice of the heart or of the aorta near the valve.
hypertrophic pyloric stenosis narrowing of the pyloric canal due to muscular hypertrophy and mucosal edema, usually in infants.
Breast Cancer Signs and Self Breast Examination Instructions
About 1 out 10 women will develop breast cancer at some time in her life. Although this oft-repeated ratio has frightened many women, it represents a woman’s lifetime risk. Thus, not until the age of 80 does a woman’s risk of breast cancer rise to 1 in 10. Here is the risk at earlier ages :
Age 50 : 1 in 50
Age 60 : 1 in 24
Age 70 : 1 in 14
Age 80 : 1 in 10
In 1995, approximately 182,000 women in the United States will have been diagnoses with breast cancer for the first time. About 46,000 women (and 240 men) will die, making breast cancer the second leading cause of cancer death for women.
Ketamine long term side effects Are you looking for ketamine long term side effects? Ketamine is a drug used in human and veterinary medicine. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA receptor antagonist. At high, fully anesthetic level doses, ketamine has also been found to bind to opioid μ receptors type 2 in cultured human neuroblastoma cells, however without agonist activity, and to sigma receptors in rats. Also, ketamine interacts with muscarinic receptors, descending monoaminergic pain pathways and voltage-gated calcium channels. Like other drugs of this class such as tiletamine and phencyclidine (PCP), it induces a state referred to as "dissociative anesthesia" and is used as a recreational drug.