Quiz for Webb HB 8/3

An important defense against disease in vertebrate animals is the ability to eliminate, inactivate, or destroy foreign substances and organisms. Explain how the immune system achieves all of the following.

1. Provides an immediate nonspecific immune response
2. Activates T and B cells in response to an infection
3. Responds to a later exposure to the same infectious agent
4. Distinguishes self from nonself

White blood cells are produced in lymph nodes, the spleen and bone marrow. White blood cells are responsible to defend against pathogens that are entering the body. When there is a pathogen threat or an infection the number of white blood cells will rise. There are five types of white blood cells. The one that is responsible for killing invaders are lymphocytes. Lymphocytes are 25% of the white cells in the body and kill pathogens which is known as the immune response. The lymphocytes contain a large nucleus and produce antibodies that work against toxins.

 A nonspecific immune response is not antigen specific and can react to a range of invading organisms. Nonspecific response also doesn't include any memory related actions. A non-specific response is occurring with an example of a splinter in your foot. A nonspecific immune response includes things like physical and chemical barriers. Physical barriers are things like mucus and skin that protect your body from being harmed. Chemical barriers are like pH levels which can denature bacteria so that it won't infect you. Inflammation is likely to occur and this is when histamines are realized which enables the pathogen to be attacked. Inflammation also has clotting blood to try to repair the area where using the example the splinter punctured. Blood vessels alsi dilate and fluid goes out like Edema. Edema cuts of the amount of oxygen and glucose that bacteria needs. Therefore edema helps kill off bacteria and constricts blood vessels. Phagocytosis also occurs in the nonspecific response. Phagocytosis is a process when pathogens are ingested by macrophages. Macrophages trap the pathogen in a phagosome and then the phagosome binds with a lysosome. Within this lysosome digestive enzymes break down the pathogens. 

The specific immune system is actually activated by the release of a chemical called interleukin-1 by the white blood cells. This activates the responses of a kind of lymphocyte that are known as helper T cells. Helper T cells don't directly kill the pathogens they just activate T cells and B cells that kill the pathogens. T cells respond by being able to recognize non-self substances by the receptor proteins that are found on their cell membrane that correspond to the pathogen.  Our immune system actually produces large quantities of these that have different protein receptors so there can be a match with the pathogen. This match will stimulate the body to make the correct T cell to attack. However, if it is a self cell these natural killers will have an inhibitor receptor to stop the attack. T cells come from the thymus.

Helper T cells, like previously mentioned stimulate B cells and B cells have plasma cells that produce antibodies. Antibodies can block viruses from entering the body again. B cells are from bone marrow and can qualify as a memory cell and they are able to remember a pathogen. That is why being exposed to the same infectious agent can have less effects on your body because they have attacked the immune system before. So the impact of this disease is less than it previously was or none at all. A good example is that someone can't get chicken pox twice, because antibodies that were produced by B cells still exist in their bodies and protect against those antigens. There can be major problems with your immune system if there is a mutation. This called autoimmune disease. It is when the signals in MHC cells don't work properly and reads self material as non-self. You basically will have an unbalanced immune system then. MHCs are immune cells that communicate and determines self from non-self.  MHCs are also responsible for when in organ transplants an organ is rejected because the MHCs will recognize the non-self protein receptors. 

Some immune response genes regulate how antigens are attacked. Early in development if T cells do not learn how to tolerate self produced proteins the cells are terminated. Different types of T cells are kept in homeostasis balances. An example of this is when helper T cells and inducer T cells are in balance. Another example is when cytotoxic T cells are in balance with suppressor T cells. Cancer cells are cells that keep dividing and are growing out of control so the immune system has problems attacking them. Leukemia which is a type of cancer is the abnormal growth of immune cells called leukocytes (white blood cells). Lymphoma the other type of immune system cancer affects the lymphoid tissues. Cancer cells shed tumor antigen proteins. These antigens are recognized by cytotoxic T cells, killer T cells and macrophages and an attack is stimulated. However tumors grow when there is a problem with this system or it is overwhelmed.