IMMUNOLOGY*Immunology is the branch of medicine concerned with the immune system and its disorders.*FUNCTIONS OF B LYMPHOCYTESB lymphocytes have antibodies located on their surface that act as receptors for specific antigens. The main functions of B lymphocytes are to make antibodies against antigens, to perform the role of antigen presenting cells and develop memory B cells after antigen interaction. The growth and division of B cells form memory and plasma cells.These memory cells will be able to faster react if the body is invaded by the antigen again. Plasma cells are needed to produce and secrete large amounts of the antibodies. The immune system needs these antibodies to identify and send signals for immune processes to rid the body of the pathogen. *Here is a video explaining the role of B lymphocytes and the affect it has on the immune system.


Innate immunity is the front line of defense against different organisms invading the body. Structures of the nonspecific innate immunity system are both external and internal. They are inherited defense mechanisms of the body in which lymphocytes interact in a coordinated effort with phagocytes.

External Structures
  • Skin-physical barrier to penetration by pathogens. Secretes lysozyme which is an enzyme that destroys bacteria.
  • Digestive Tract-high acidity of the stomach and protection of normal bacterial population of colon.
  • Respiratory Tract- Secretes mucous, alveolar macrophages.
  • Gentitourinary Tract-acidity of urine and vaginal lactic acid naturally help immune system.
Internal Structures
  • Phagocytic Cells- Engulf and destroy bacteria cell debris, denaturated proteins and toxins.
  • Interferons-Stop the reproduction of viruses.
  • Complement proteins- Help destruct bacteria and enhance inflammatory response.
  • Endogenous pyrogen- produce fever.
  • Natural Killer (NK) cells-destroy cells infected with viruses, tumor cells and mismatched transplanted tissue.
  • Mast Cells- release histamine and other mediators of inflammation.

DISEASES CAUSED BY THE IMMUNE SYSTEMImmune mechanisms that normally protect the body are very complex and subject to errors which can result in diseases. Autoimmune diseases and allergies are the two categories that aren't caused by an invading antigen, but rather by a discrepency in the functions of the normal immune system. AUTOIMMUNE DISEASES: When the immune system develops a response against themselves, attacking it's own cells and tissues. Ex. Type 1 diabetes, multiple sclerosis, graves' disease, throiditis, psoriasis and systemic luppus erthyematosus. IMMUNE COMPLEX DISEASES: Immune complexes are antigen-antibody combinations that are not attached to other free cells. These combinations are made up of active complement proteins and inhance inflammation sometimes leading to widespread inflammation and causing organ damage. .
Ex. malaria, hepatitis
ALLERGIES: Hypersensitivity to specific allergens (antibodies) that are often harmless in most people; symptoms vary greatly in intensity. The two different allergic reactions are called immediate and delayed hypersensitivity. In immediate, the symptoms will come on quickly and involve B-lymphocyte response. In delayed hypersensitivity, the symptoms take between 1-3 days to occurEx. Immediate-hay fever, food allergies, bee stings.Ex. Delayed-poison ivy, poison oak.*

Example of an allergy test. *APPLICATIONIn my nursing career, I see many disease processes occuring. Sometimes it's malignant cancer and sometimes it's a simple infection. Whatever the case is, it is important for me to know how the body defends and reheals itself at a deeper level so I can be providing not only appropriate care, but knowledge based. I give a lot of vaccines to patients (never really understanding how they work) so it was beneficial for me to read about active immunity and how they protect the body. *ESSENTIAL QUESTIONCompare and contrast the different categories of the immune system. ACTIVE IMMUNITY VS PASSIVE IMMUNITY: In active immunity, the body produces antibodies against a specific antigen, is permanent and will stay with the person their entire life. Active immunity can be acquired by getting a specific infectious disease (chickenpox or be getting a vaccine.In passive immunity, the body does not develop it's own immune response. It occurs by the transfer of active immunity, in the form of ready-made antibodies. Passive immunity can occur both naturally or be artificially induced. The transfer of antibodies from mother to fetus through the placenta and from mother to child while nursing are examples of natural passive immunity. Passive immunity provides immediate resistance, but only lasts for a short time (days to weeks) while active takes longer to build up but is permanent.INNATE IMMUNITY VS ADAPTATIVE IMMUNITY: Innate immunity is something that everyone is born with and is called "the first line of defense" against invading pathogens. It can easily recognize a plethora of specific pathogen and provides a quick response. It utilizes both the enternal and external defense mechanisms. Adaptive immunity is the acquired ability to defend itself against invading pathogens. It also uses internal defenses and recognizes specific pathogens but isn't inherited. It provides a slower response time than innate immunity. CELL-MEDIATED IMMUNITY VS HUMORAL IMMUNITY: Cell mediated immunity works against infection in the cells while humoral immunity works against infection in the body's fluids. Cell mediated immunity involves T cells while humoral involes cytotoxic T cells. In comparison, both produce memory cells allowing for a much a faster response time if the body is invaded again by a specific pathogen. *"DESCRIBE THE PROCESS OF LOCAL INFLAMMATORY RESPONSE"When bacteria enters the body through the skin, phagocytic cells that are localized in that area spring to action with the help of complement proteins. When the complement proteins are called to duty, they attract B lymphocytes. The B cells then bind to the bacteria which weakens it (so that the phagocytes can locate and destroy the bacteria much easier). The B cells also create antibodies which will begin attracting more phagocytes to the area. If the infection continues, the complement proteins stimulate the mast cells which will begin secreting heparin, histamine, prostaglandins, leukotrienes, cytokines, and TNF-a. These will produce the signs and symptoms of an infection. Leukocytes will also begin coming to the site, along with endogenous pyrogens. Signs and symptoms of an infectioninclude pain, drainage (pus), swelling, redness and warmth. *