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Terms in this set (42)
this system responds quickly to protect the body
from pathogens and infection.
There are two major lines of defense that make up the Innate Defensive System:
Surface barriers or internal defenses
which prevent the penetration of pathogens into the body.
Surface barriers of external body membranes
which includes a variety of proteins, cells and phagocytes which work together to prevent the spread of pathogens throughout the body.
This system works well as long as the thick keratinized epithelial tissue of the skin is not broken.
Surface Barriers: Skin and Mucosae
line body cavities that open directly to the outside of the
body. Specific functions of mucous membranes in innate body defense
cells that feed on and destroy invading microorganisms.
Types of Phagocytic Cells
primary phagocytes in the body. These are
derived from leukocytes known as monocytes which leave
-most abundant and die fighting
another type of leukocyte in the body, these can
be phagocytic but they are best known for fighting parasitic worms.
move throughout the body searching
for and destroying foreign invaders
Kupffer Cells in the liver and microglia
in the brain are examples
cells in the blood and lymph that can lyse and kill cancer
cells and virus-infected cells before the adaptive immune response is initiated.These are not specific and they develop from granular leukocytes. These destroy cells by releasing chemicals known as perforins which destroy the nucleus of cells (Killer Cells are not phagocytic).
The inflammatory response is initiated when body tissues are injured
Benefits of Inflammation:
a.Prevents the spread of damaging agents into the body.
b. Removes cell debris and pathogens
c. Sets the stage for repair.
Events in Inflammation
Inflammation begins when chemicals and cells leave blood vessels and move into the injured tissue. Chemicals such as cytokines, histamine, kinins and prostaglandins all promote small blood vessels
What Mobilizes Phagocytic Cells During Inflammation
the release of phagocytic cells (especially neutrophils) into blood vessels. Within hours, these cells are transported to the site of injury. This is triggered by leukocytosis-inducing factors
the movement of neutrophils through the walls of capillaries into the site of inflammation.
Types of antimicrobial proteins include
stimulate healthy cells to produce a protein known as PKR which functions by preventing viruses from undergoing protein synthesis.
this refers to a group of plasma proteins that circulate
through the blood in an inactive state. These proteins are activated by the immune response itself.
This specific system protects the body from a wide range of microorganisms and abnormal body cells. This system is turned on by exposure to a foreign substance
. Important Characteristics of the Adaptive Defense System
. It is specific-it recognizes and attacks particular pathogens or foreign debris in the body.
2. It is systemic-immunity is not restricted to the site of the initial infection.
3. It has memory-after an initial exposure, it recognizes and strongly attacks a previously encountered pathogen.
substances that can mobilize the immune system and provoke an immune response.
Antigens are classified as being either complete or incomplete
Complete Antigens-have 2 key characteristics:
Immunogenicity-the ability to stimulate the formation of
specific lymphocytes and antibodies. Most proteins, nucleic
acids and polysaccharides can serve as complete antigens.
2) Reactivity-the ability to react with the activated lymphocytes and the antibodies released by immunogenic reactions.
self antigens, these are a group of
proteins that mark cells as ours. These are strongly antigenic to other individuals (this is the basis for rejection of tissues and transfusions
Major Histocompatibility Complex (MHC)-
Originate in the bone marrow from hematopoietic stem cells. When released, mature into either B cells or T cells
T cells become immunocompetent (able to recognize a
specific antigen by binding to it)
produced by antibodies present in the body's fluids. Antibodies bind to pathogens, inactivating them and marking them for destruction by phagocytes or the complement system.
occurs when lymphocytes themselves defend the
body from microbial invasion. These cells can produce cell lysis or they can initiate an inflammation response
occurs when someone is reexposed to a particular antigen. This response is fast and extremely effective since the immune system is on alert for the antigen. This is known as Immunological Memory
Secondary Immune response
). Active immunity is naturally acquired when you are exposed to pathogens. It can also be artificially acquired when you receive vaccines.
contain dead or weak pathogens or their
are secreted by activated B Cells or Plasma
The five major classes of antibodies are
IgA,:Helps prevent entry of pathogens
IgD: functions as B cell receptor,
IgM: First antibody relases,
IgE: causes mast cells and basophils to relase histamine,
IgG: from secondary and late primary responces
Types of Antigen-Antibody reactions include:
1) Complement Fixation and Activation-antibodies bind to cells and change shape. This triggers complement fixation and cell lysis.
2) Neutralization-occurs when antibodies block specific sites on viruses or toxins. This prevents the antigen from attaching to tissue receptors; thus, preventing injury to the tissue.
3) Agglutination-antibodies can cause antigens to clump. This clumping is known as agglutination. Where might this occur in the human body
chemicals released by T Cells, these help to enhance the immune response
stimulate proliferation of other T Cells and B Cells that
are attached to an antigen.
Helper T cells
directly attack and kill other cells. Their main targets
are virus-infected cells
Cytotoxic T Cells
suppress the activity of B Cells and T Cells. Are
thought to inhibit autoimmune reactions.
Supresser T cells
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