Immune System
Infection and Immunity Skin (integumentary system) is first line of nonspecific defense in protecting body against any foreign invader (pathogen) that can cause infection (usually viruses or bacteria) since it provides a barrier Break in skin barrier allows pathogen to enter & infect Second line of nonspecific defense is phagocytosis (white blood cells that eat invader)
If phagocytes cannot prevent pathogen from infecting, body undergoes specific defense in which it identifies and targets specific pathogen Pathogen is now considered an antigen since it causes immune response (usually a virus) Body produces specific Y-shaped proteins called immunoglobulins (Ig) or antibodies (ANTI-body) to kill antigen (ANTIbody GENerator) using lock & key mechanism (antigen = key, antibody = lock)
Antibody is produced when helper T-cell (from Thymus) causes B-cells (from Bone) to construct specific antibody Antibodies bind to antigen, now phagocytes can eat and destroy them Entire process takes 7-10 days Some B cells turn into Memory B cells that will always be prepared to immediately kill same antigen so that individual never experiences symptoms
Vaccines A vaccine is an injection of weakened or dead antigen into the body The immune response produces antibodies as body can’t tell it’s harmless. Antibodies with phagocytes destroy antigens Memory-B cells permanently remember antigen so if body encounters it again, immediate attack occurs before disease symptoms develop making individual immune from disease
Bacteria & Viruses A microbe is anything too small to be visible to the naked eye. Two types of microbes are bacteria and viruses. Bacteria are single-celled prokaryotic living organisms Viruses may have a spiny outside layer, called the envelope. Viruses have a core of genetic material (DNA or RNA), but cannot reproduce on their own. They infect cells and take over their reproductive machinery to reproduce. They are not considered living.
Bacterial infections can be treated with the non- specific immune response or antibiotics, medicines that destroy prokaryotic bacteria without harming eukaryotic humans Viruses cannot be treated with any medicines, solely the immune response
Compromised Immunity If the immune system is compromised or not working, individual may not be able to survive simple infections like flus or pneumonia In AIDS (Acquired Immune Deficiency Syndrome), T-helper cells are infected by HIV (Human Immunodeficiency Virus), thus weakening immune system AIDS patient usually dies from pneumonia