Immunology+Intro

=**Introduction to Immunology**=

Dr. Takashima 25 Aug 2008, 10-11 AM

=Objectives (2007)=

Immunology is the study of the physiological mechanisms that humans and other organisms use to defend their bodies from invasion by other organisms. The origins of immunology lie in the practice of medicine and in historical observations that people who survived an epidemic disease were immune when faced with that same disease again.
 * To explain what is "immunology."**

Infectious diseases are caused by microorganisms, which have the advantage of reproducing and evolving much more rapidly than do their human hosts. Because the immune system protects against infectious microbes including viruses, bacteria, fungi, and parasites, the study of immunology is inextricably linked to the study of microbiology. During the course of an infection, the microorganism can pit enormous populations of its species against an individual //Homo sapiens//. In response, the human body invests heavily in cells dedicated to defense, which collectively form the immune system.
 * To restate relationship between immunology and microbiology.**

The immune system is designed to protect the body against pathogenic microorganisms as well as serve a surveillance role against cancer. Immune dysfunction can result in the invasion of the body by viruses, bacteria, fungi, and parasites which can cause pathology. Additionally, immunodeficient individuals, such as transplant recipients who are immunosuppressed, tend to have an elevated incidence of certain aggressive cancers such as squamous cell carcinoma of the skin.
 * To list examples of diseases caused by immune dysfunction.**

Additionally, the immune system sometimes fails to recognize certain cells or particles as "self" resulting in the development of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. Certain substances can trigger the immune system to be hyper-reactive, causing allergic diseases like asthma, hay fever, or atopic dermatitis.

Graft rejection and graft versus host disease are undesirable conditions caused by the immune system during organ and bone marrow transplantations. Lastly, different defects resulting in immunodeficiency will produce distinct phenotypes, depending on which immune cells are missing or defective.

There are three lines of host defense against pathogens. The first defense in physical or chemical barriers such as the stratum corneum of the skin or mucosal tissue lining the GI and respiratory tracts. These barriers are designed as a physical barrier, by blocking pathogens from access to the body, and sometimes as a chemical barrier, by releasing antimicrobial peptides or proteolytic enzymes to kill foreign pathogens.
 * To outline three lines of host defense against pathogens.**

The second line of defense is innate immunity, which regulates the inflammatory response (heat, pain, redness, swelling, etc.) The innate immunity system has a variety of receptors the detect foreign pathogens. When a pathogen is detected, leukocytes, macrophages, and complement act to destroy the pathogen.

The third line of defense is adaptive immunity, which, unlike innate immunity, is highly customized to be highly antigen specific. However, because of their specificity, they are slower to respond because of the clonal expansion time necessary to build up effector B cells and T cells. However, once the cells are activated and expanded, the adaptive immunity allows for long-term protection against subsequent re-exposure to antigen.

Its important to study immunology because it is a crucial system to human survival. Without a working immune system, even minor infections can take hold and prove fatal.
 * To recognize the importance of studying immunology.**