Immune System

Basic Immunology
• The Immune system must have the ability to distinguish
between self and non-self molecules
• Self Molecules- components of an organism’s body that can be
distinguished from foreign substances by the immune system.
Autoimmunity- immune reaction against self molecules
• Non-self Molecules- recognized as foreign molecules
Ex: Antigen (short for antibody generators)
Immune System: Responsible for protecting the animal from
potentially harmful organisms attempting to invade the body.
Pathogen: virus, bacteria, fungi, parasites, etc. that can do harm to
the body
Non-specific (Innate) Immunity
1st line of defense: skin, mucous membranes, stomach acid
2nd line of defense: inflammatory response (bringing blood, fluid and
cells to the site to fight off the pathogen); phagocytes (a type of white
blood cells that can engulf and eat up foreign matter that it knows is
bad to the body)
Vaccination: administration of antigen (vaccine) to stimulate a
protective immune response against a specific infectious agent (aka:
Immunity: the state of being resistant to a specific disease. Different
forms of immunity are obtained during life.
Antigen: substance that the body regards as foreign and may be
capable of stimulating an immune response.
Antibodies: disease or infection-fighting proteins produced by
the body in response to the presence of a specific antigen.
Specific /Adaptive Immune System ~
Naturally Acquired Passive Immunity: immunity resulting from transfer
of antibodies from one animal to another through mother to offspring
either before birth or in colostrum (first milk of newborn).
Naturally Acquired Active Immunity: resistance to a specific disease
after the development of antibodies during the actual disease
Artificially Acquired Passive Immunity: resistance to a specific disease
by receiving antiserum-containing antibodies from another host
Artificially Acquired Active Immunity: resistance to a specific disease
through vaccination
The immune system is activated when the 1st line of defense fails.
Immunology: study of the immune system
Lymphocytes: type of white blood cells that are involved in the
immune response and work against specific agents. They are formed
in the bone marrow and grow in lymphatic tissue throughout the
body, such as bone marrow.
Two categories of lymphocytes are:
T cells: (thymus-dependent) responsible for cell-level
immunity and direct attack the invading antigen. Most effective
against viruses that infect the body cells, cancer cells, and foreign
tissue cells.
B cells: (bone marrow-derived) produced and mature in bone
marrow and make antibodies that react with the antigen. Most
effective against bacteria, viruses, and toxins. Also involved in allergic
Lymphatic System
 One way system: to
the heart
 Return of collected
excess tissue fluid
 Return of leaked
 “Lymph” is this fluid
 Edema (build-up of
fluid) results if system
blocked or surgically
The Immune System
 Recognizes specific foreign molecules
 Each exposure (to the same pathogen) increases the effectivity of
the response
 Lymphoid organs
 Lymph nodes-small, bean-shaped structures; filter lymph and
store B and T lymphocytes. Filter lymph to remove harmful
substances (bacteria/viruses). Swollen lymph nodes sign of
 Spleen- located in abdomen; filters foreign material from blood,
stores red blood cells, maintains balance of cells and plasma in
 Thymus- Found in young animals (disappears as animals age) in
thoracic cavity. Develops T cells.
 Tonsils- tissue that protect nose and upper throat.