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Human health risks Free essay! Download now

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Human health risks

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Downloads to date: N/A | Words: 2065 | Submitted: 26-Jun-2011
Spelling accuracy: 96.7% | Number of pages: 4 | Filetype: Word .doc


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Human health risks

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1)
The immune system is a group of cells, molecules, and tissues that help defend the body against diseases and other harmful invaders.   The immune system provides protection against a variety of potentially damaging substances that
can invade the body.   These substances include disease-causing organisms, such as bacteria, fungi, parasites, and viruses.   The body's ability to resist these invaders is called immunity

The immune system is composed of many parts that work together to fight antigens when they invade the human body.    The immune system reacts to foreign substances through a series of steps know as the immune response.   Any agent perceived as foreign substance by the body's immune system, is called an antigen.   Several types of cells may be involved in the immune response to antigens.


When an antigen enters the body, it may be attacked by phagocytes or by antibodies that act together with the   human immune system containing approximately 1 trillion T cells and 1 trillion B cells, located in the lymphoid organs and in the blood, plus approximately 10 billion antigen-presenting cells located in the lymphoid organs. To maximize the chances of encountering antigens wherever they invade the body, lymphocytes continually circulate between the blood and certain lymphoid tissues. A lymphocyte spends an average of 30 minutes per day in the blood and circulates about 50 times per day between the blood and lymphoid tissues.

Everyday my body is able to fight off harmful invaders. I make sure to eat nutritious meals so that my immune system response will not be impaired. I know the importance of having the essential vitamins and minerals, as well as the disadvantage of the effect on my immune system if I don’t get enough of the nutrients that I need. Because I know that “malnutrition compromises immunity”, I can’t help but to eat right to increase my chances of staying healthy.


2.
? Pest resistance Crop losses from insect pests can be staggering, resulting in devastating financial loss for farmers and starvation in developing countries. Farmers typically use many tons of chemical pesticides annually. Consumers do not wish to eat food that has been treated with pesticides because of potential health hazards, and run-off of agricultural wastes from excessive use of pesticides and fertilizers can poison the water supply and cause harm to the environment. Growing GM foods such as B.t. corn can help eliminate the application of chemical pesticides and reduce the cost of bringing a crop to market4, 5.
? Herbicide tolerance For some crops, it is not cost-effective to remove weeds by physical means such as tilling, so farmers will often spray large quantities of different herbicides (weed-killer) to destroy weeds, a time-consuming and ...

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