Human Physiology 15
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What system of the body includes all the structures and mechanisms that provide a defense against potential pathogens?
the immune system
What are the two main categories of defenses within the immune system?
- innate (nonspecific) immunity
- adaptive (specific) immunity
What type of immunity is inherited to act against the broad categories of pathogens but not specific one?
What type of immunity protects an organism against specific pathogens?
What type of nonspecific immune defense is made of physical structures that prevent pathogens from invading an organism?
What are two types of barriers?
skin and mucous membranes
How does the innate immune system distinguish between self and invading pathogens?
by recognizing pathogen-associated molecular patterns (PAMPs)
What are chemical signals produced by cells of the immune system to recruit other cells of the immune cells?
What are the three major groups of phagocytic cells?
- mononuclear phagocyte system cells
- organ-specific cells
What is the term for phagocytic cells fixed and immobile inside of the liver, spleen, and lymph
What phagocytes are the first to arrive at the site of an invasion of pathogens?
What phagocytic cells arrive at a site of pathogenic invasion after neutrophils?
Monocytes transform into what type of cells?
How do phagocytic cells travel from blood vessels to sites of infection?
What cytokine is released by leukocytes and the brain to produce fever?
What may be the adaptive value of a fever?
It may inhibit the growth of bacteria and increase the activity of neutrophils and increase the production of interferon.
What are substances released by cells infected with a virus in order to inhibit the ability of a virus to replicate within other cells?
What are proteins that attach to antigens as a part of an immune response?
What are molecules (usually proteins or carbohydrates) that stimulate the production of antibodies?
What are the specific portions of antigens that stimulate antibody production and combine with
antigenic determinant sites
What are small, organic molecules that are not antigenic by themselves, but which can become
antigens if they bind to proteins?
What are tests in which the binding of antigens to antibodies can be detected through visible agglutination?
What type of leukocyte matures in the thymus and is involved in cell-mediated immunity?
T cells (lymphocytes)
What type of leukocyte is processed in the bone marrow and is involved in antibody-mediated
B cells (lymphocytes)
What are the two primary lymphoid organs?
bone marrow and the thymus
What are the four secondary lymphoid organs?
- the lymph nodes
- Peyer's patches
During a local inflammation what initiates the reaction?
phagocytosis and complement activation
What is the role of histamine in a local inflammation?
- Histamine relaxes vascular smooth muscle thus increase blood flow into the area. It also increases
- capillary permeability
What are the characteristics of a local inflammation?
A B cell stimulated by an antigen divides into what two types of cells?
What type of activated B cell produces antibodies?
a plasma cell
What type of B cells are produced by activated B cells to live on and keep an organism prepared for
an infection by the same antigen at a later time?
What is the general shape of an antibody?
The four protein chains of an antibody are of what two types?
heavy chains (2) and light chains (2)
An antibody has two general regions. What region does not interact with the antigen and is common
within a particular category of antibody?
the constant region
An antibody has two general regions. What region interacts directly with an antigen?
the variable region
The specific antibody a B cell produces, even before activation of the cell, serves what function?
What are the three results of antibodies attaching to a pathogen?
- They increase the activity of phagocytes.
- They promote the activation of the complement. They precipitate antigens out of solution.
What is the series of proteins which act as nonspecific immune mechanism to create holes in the cell walls of bacteria? They are produced by the liver.
What type of T cell functions to destroy cells that harbor foreign molecules?
killer (cytotoxic) T cells
What type of mechanism do killer T cells use to destroy victim cells?
What two molecules are released by killer T cells to destroy other cells?
perforins and granzymes
How do perforins bring about the destruction of cells?
They enter the plasma membrane to form large pores
What is the role of granzymes?
They enter the victim cell and activate caspases which destroy the cell's DNA
Killer T cells are involved in the destruction of what type of cells and pathogens?
viruses, fungi, cancer, and some bacteria
What is the function of helper T cells?
They enhance the immune response
What is the effect of helper T cells on B cells?
- They improve the ability of B lymphocytes to differentiate into plasma cells and secrete specific
What is the effect of helper T cells on killer T cells?
They enhance the ability of killer T cells to function in cell-mediated immunity.
What type of chemical regulators do helper T cells use to enhance the function of the immune system?
What type of T cells inhibits the activity of B cells and killer T cells?
regulatory (suppressor) T cells
The proper function of Treg cells guards against what two potential problems with the immune system?
allergies and autoimmune diseases
What are polypeptides that are classified within any of the classes of immunoregulatory proteins (as interleukin, tumor necrosis factor, and interferon) that are secreted by cells especially of the immune
What are cytokines produced by lymphocytes?
T cell receptors cannot bind to a free antigen and thus cannot react to them. How must antigens be presented to them?
on the membranes of antigen-presenting cells
With the exception of RBCs, how are all cells in the body labeled?
with histocompatibilty antigens on the cell membrane's surface
What term refers to histocompatibility antigens in humans?
human leukocyte antigens (HLAs)
What are the two major antigen-presenting cells that interact with T cells?
macrophages and dendritic cells
From what type of WBC are macrophages and dendritic cells derived?
What group of four genes located on chromosome 6 determines the histocompatibility antigens of an
the major histocompatibility complex
When a macrophage or dendritic cell phagocytisizes a pathogen, what does it then do?
- It partially digests it and combines the pathogen's antigens with class 2 MHC molecules on its cell
- membrane to present them to T cells
In addition to the presentation of an antigen combined with a MHC molecule, how does a macrophage stimulate helper T cells?
with a cytokine
Helper T cells are stimulated by macrophages. How do T cells, in turn, stimulate macrophages?
In order for killer T cells to destroy infected cells, what must the infected cells do?
display the foreign antigen with their class-1 MHC molecules
In addition to releasing lymphokines, how do helper T cells stimulate B cells?
- The activated helper T cell must interact with the foreign antigen presented by the B cell along with
- the B cells class-2 MHC molecule
After an infection clears what happens to activated T cells?
They undergo apoptosis
What triggers the apoptosis of activated T cells after an infection ends?
- T cells put a recptor, FAS, on their membranes and later release FAS ligand which interacts with the
- receptor to bring about apoptosis
When a person is first exposed to a particular pathogen there is a sluggish response period of 5 to 10 days before a measurable rise in antibodies against that pathogen. What is the reaction called?
the primary response
After an initial exposure to a pathogen, subsequent exposures result in very rapid increase in antibody production and prevent symptoms from developing. What is this reaction called?
the secondary response
What theory explains the primary and secondary responses seen in an immune reaction?
the clonal selection theory
What type of B cell produces antibodies?
What is a long-lived lymphocyte that carries the antibody or receptor for a specific antigen after a
first exposure to the antigen and that remains in a less than mature state until stimulated by a second
exposure to the antigen at which time it mounts a more effective immune response than a cell which
has not been exposed previously?
a memory cell
What are the locations developed from stimulated B cells undergoing rapid division?
What organs contain germinal centers?
secondary lymphoid organs (spleen, lymph nodes, tonsils, Pyerís patches)
What type of immunity develops in response to expose to an antigen and the subsequent development of a secondary response?
What substances are used to bring about the development of an active immunity without developing symptoms of a disease during the primary response?
What two types of pathogens are used as vaccines? These expose the patient to the antigen, but do
not result in the development of symptoms.
- attenuated or destroyed
- antigenically similar
What term refers to antigens created by one organism and exposed to another?
What term refers to antigens created by an organism?
When is the ability to distinguish between non-self and self-antigens developed?
in the first month or so of postnatal life
What are antibodies that attach to self-antigens?
What are T cells that attack self-antigens?
autoreactive T cells
What mechanism that may account for the development of immunological tolerance involves the destruction of the lymphocytes that recognize self-antigens?
What mechanism that may account for the development of immunological tolerance involves the presence of lymphocytes directed against self-antigens throughout life, but which do not attack those antigens?
What two theories may account for immunological tolerance?
the clonal deletion theory -the clonal anergy theory
What type of T cells is believed to play an important role in immunological tolerance?
What term refers to the immune protection that can be produced by the transfer of antibodies to a recipient from a human or animal donor?
What are three ways in which passive immunity may be given?
- across the placenta
What are commercially produced antibodies that are specific for only one antigenic determinant site?
In addition to passive immunity, what are three other uses of commercially produced antibodies?
research -laboratory testing -therapy
What is the study of tumors?
What are tumors that grow slowly and are limited to specific locations?
What term refers to tumors that are growing rapidly and have the ability to spread throughout the body?
What is a change of position, state, or form, as a transfer of a disease-producing agency (as cancer
cells or bacteria) from an original site of disease to another part of the body with development of a
similar lesion in the new location?
What term refers to malignant tumors?
What process do cancer cells undergo which takes away their specialization and the antigens that are
not normally present postnatally?
What process may occur in which the body constantly searches for cancer cells and destroys them if they occur?
What type of lymphocyte is a part of the innate immune system and destroys viruses, bacteria, parasites, and cancer cells through cell-to-cell contact?
natural killer cells
What substances do natural killer cells use to destroy their targets?
perforins and granzymes
What type of cancer treatments involves the use of such things as inferons and interleukins and T
What two factors relating to the activity of the immune system may account for the increase in
the incidence of cancer later in life?
- a regression of the thymus
- an accumulation o f genetic errors in aging lymphocytes
How might stress be related to cancer?
Stress causes immunosuppression
List three categories of diseases caused not by pathogens but by abnormal responses of the immune system.
- autoimmune diseases
- immune complex diseases
- allergies (hypersensitivity)
What type of diseases is caused by the failure of the immune system to recognize and tolerate self-antigens?
Rheumatoid arthritis, type 1 diabetes mellitus, multiple sclerosis, Grave's disease, glomerulonephritis, thyroiditis, pernicious anemia, psoriasis, and systemic lupus erythematosus are examples of what type of disease?
What type of diseases result in inflammation due to free antigen-antibody complexes that are not attached to bacterial or other cells?
immune complex diseases
What term refers to abnormal immune responses to substances that do not normally act as antigens?
What type of allergy involves abnormal B cell response to an allergen that produces symptoms within seconds or minutes?
What type of allergy involves an abnormal T cell response that produces symptoms between 24 and 72 hours after exposure to an allergen?
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