Biology of Health and Illness
Factors which affect the normal functioning of two body systems
The body's first line of defence against pathogens uses mostly physical and chemical barriers such as sweat, skin, tears, mucus, stomach acid, and so on. Our skin and other membranes which line the body passages are fairly effective in keeping most pathogens out of the body. Mucus can trap pathogens, which are then washed away or destroyed by chemicals. Tears, sweat, and saliva have certain chemicals which can kill different pathogens.
Bacterial spores and fungi are naturally present in the environment. The spores are so small they can only be seen by a microscope. However, they play a large role in the decomposition of organic matter in the open, such as breaking down the components of fallen leaves or dead trees. However, when found indoors, bacterial spores pose a serious health risk. The type and harshness of the symptoms of inhaling bacteria are dependent on how much bacteria was inhaled or ingested, and they also vary based upon the person and the person's sensitivities or allergies.
One of the most common symptoms of inhaling bacteria is experiencing allergic reactions. These symptoms bear a resemblance to those of hay fever; they include sneezing, runny nose and watery eyes that appear red. You may also experience skin rashes, nasal congestive, and sensitivity to light, headaches, and tiredness. People with asthma problems are highly susceptible to attacks which include wheezing, tightening of the chest and difficulty in breathing.
People who have weakened immune systems are more vulnerable to infections caused by the inhalation of bacteria. They attack the eyes, skin and lungs. The first line of defence helps the body’s defence system stop most of the bacterial spores and fungi be inhaled by using the nasal hair and mucus.
If microbes get past your first line of defence, it is up to the second line of defence, your immune system, to keep you from getting sick. The immune system is made up of lots of different cells that are always patrolling your body and fighting any bad microbes they find. Your body is exposed to many different types of microbes every day, so your immune system is always working.
When you get a cut or scrape, immediately bacteria and germs try to get into your body. This is when the immune system takes over. The immune system is made of various cells and proteins. The complement system is the first area that meets antigens, or foreign invaders, and takes action. It is made up of phagocytes and lymphocytes. Phagocytes are responsible for finding and eliminating bacteria and viruses. The three main types are granulocytes, macrophages and dendritic cells. Lymphocytes are white blood cells. The two main cells for the lymphatic system are T cells and B cells.
The first thing that happens when you get a cut is granulocytes, macrophages and dendritic cells, or phagocytes, devour the bacteria and viruses. Both the macrophages and dendritic cells activate one kind of T cells, the helper T cells, by presenting the antigen. Meanwhile, B cells find certain antigens that they are specialised for. The helper T cell then activates the B cells, which causes the B cell to divide into a plasma cell and a memory cell. The plasma cell is able to send out antibodies that attach to the foreign invader. Although the phagocytes are able to destroy antigens without antibodies, they prefer those with antibodies. The antibodies cause the phagocytes to eliminate more at the time. The memory cell later remembers that antigen, so if it invades again, the immune system is able to attack it quicker.
Pathogens contain certain chemicals that are foreign to the body and are called antigens. White blood cells called lymphocytes carry a specific type of antibody - a protein that has a chemical 'fit' to a certain antigen. When a lymphocyte with the appropriate antibody meets a dangerous foreign...
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