Tuesday, February 26, 2013


While immunity is being acquired a person develops symptoms of the disease. But some infections can be prevented by allowing the body to acquire active immunity artificially. This is achieved by the introduction into the body of a vaccine made from dead or weakened microorganisms that are no longer capable of causing the disease itself. When injected into the skin or bloodstream (or as in the case of polio vaccine, swallowed) they stimulate B lymphocytes to produce antibodies but no significant disease symptoms. And if, or when, the body encounters the real disease causing microorganisms, it is already protected against infection because the memory cells immediately produce antibodies.

Booster shots may be needed at later dates to ensure that active immunity is still effective. Vaccines are available against many formerly dangerous diseases including polio, measles an d diphtheria. Immunization programmes for children have virtually eliminated most common childhood diseases, and confer immunity into adult life. But vaccination is advisable for travelers to countries where they may contract potentially fatal diseases not previously encountered. Sometimes antibodies themselves from external sources are injected into the body to provide protection without stimulating the immune system. This is called artificial passive immunity and is useful in providing instant protection where a disease might kill the person before their active immune system has time to come into operation. Examples include gamma globulin, given against hepatitis A infection; anti toxin to treat tetanus; and anti rabies injections.

Wednesday, February 20, 2013

Diets and Dieting!

The word diet is commonly used these days to describe an eating regime followed by someone in order for him or her to lose weight, even though in its correct usage the word simply describes what we eat each day. A diet designed for weight loss is better described as a slimming diet, and there are many of these to choose from. As the percentage over weight and obese children and adults in the western world steadily increases as a result of increased in activity and increased consumption of junk food – so new slimming diets, and books on slimming, become available in order to commercially exploit fatness. However, most of these diets are not effective because they fail to promote long term weight loss and in fact may well cause the slimmer to end up fatter and heavier than when they started the diet. Being overweight will of course affect an individual’s health and reducing body weight will help to reduce those health risks. But to be healthy, a diet designed to reduce body weight needs to be in tune with the body’s physiology.

 An effective diet should promote the loss of fatty or adipose tissue from the body so that its overall fat content is reduced. To do this successfully, the dieter should eat a well balanced high carbohydrate, high fiber low fat diet with energy content of between 1200 and 1500 calories per day, combining this with regular exercise. This should cause a weight loss of 0.45 to 0.95 KG per week, that weight loss being mainly in the form of fat. At the same time, exercise will build up muscle tissue which pound for pound consumes far more energy than fat does as well as increasing metabolic rate, the rate at which the body burns carbohydrates and fat to release energy. Once the desired weight has been reached – and the body fat content has been reduced to within safe limits- then the dieter can gradually increase his or her calorie consumption while maintain the same balance of foods in order to keep at the weight for life.

Other sliming diets put the body in a defensive stance. Because its calorie intake has been severely reduced the body reduces its metabolic rate to conserve its fat energy reserves and actually burns lean muscle tissues in order to provide energy. When the diet stops the body diverts as much spare food energy as possible to build up its fat reserves in case another calorie famine happens and in consequence the diet regains lost weight and ends with more fat than before