Biology Ch 24: Immunity
The antigen-binding sites of an antibody molecule are formed from the molecule's variable regions. Why are these regions called variable?
-They can be different shapes on different antibody molecules. -The components of the genes that code for these regions are constantly reorganized, causing new variations to be produced within each generation. -The structure of these antibody regions is different from one antibody to the next. -This structural variety accounts for the diversity of lymphocytes and gives the humoral immune system the ability to react to virtually any kind of antigen.
Antibody
A macromolecule produced in the body that recognizes another molecule as "foreign" to the body
_____ is an example of an immunodeficiency disease.
AIDS
How does antigen-antibody binding result in destruction of the antigen?
Antibodies bind the antigen, which then targets the antigen for elimination by innate mechanisms.
Viruses and bacteria in body fluids are attacked by _____.
Antibodies from B cells Antibodies form the part of adaptive immunity known as the humoral immune response. Circulating antibodies encounter microorganisms in body fluids and complex with them.
What is the primary cell type involved in humoral immunity?
B cells are responsible for antibody production in humoral immunity.
Which of the following inflammatory responses is characteristic of only a systemic response?
Bacteria and toxins enter the bloodstream, and the white blood cell count increases significantly.
Which of the following statements regarding innate immunity is correct?
External barriers such as the skin barrier, exoskeleton, and mucous membranes contribute to innate immunity.
Which statement correctly describes drug resistance and AIDS?
HIV mutates rapidly because its genetic material is RNA rather than DNA. As result, mutations, including drug-resistance mutations, can accumulate rapidly.
What is the key difference between active immunity and passive immunity?
In active immunity, a body produces its own antibodies; in passive immunity, a person receives pre-made antibodies.
How does HIV destroy helper T cells?
It initiates apoptosis in infected helper T cells.
Tissues are typed before an organ transplant to make sure that the _____ of donor and recipient match as closely as possible.
MHC (major histocompatibility complex) proteins
An antigen-presenting cell is a _____.
Macrophages can act as antigen-presenting cells. After breaking up the antigen, parts of it are attached to the macrophage's self proteins and displayed at the cell surface.
Which of the following statements regarding the cell-mediated response is correct?
Macrophages digest the antigen to break it up into its components, which are then bound by and presented to the cell surface for removal.
Which cell type is responsible for the secondary immune response?
Memory cells are rapidly activated upon repeated exposure to the same antigen.
How do memory cells differ from effector cells?
Memory cells live longer.
Which is the most likely explanation for why lymph is returned to the circulatory system via veins?
The interstitial fluid captured by the lymphatic system is low in oxygen
What organs make up the lymphatic system?
The spleen, along with the tonsils, lymph nodes, adenoids, and the appendix, is a lymphatic organ.
The thymus is most active during childhood. A child with a malfunctioning thymus will have trouble with __________.
The thymus produces T cells, which function primarily in cell-mediated immunity, but they also stimulate B cell action.
T and B cells are types of _____.
The vertebrate body is populated by two main types of lymphocytes: B lymphocytes and T lymphocytes.
Which of the following is initiated by the binding of antibodies to antigens?
activation of complement proteins The complement system is activated by antibody-antigen binding. Complement components assemble on the pathogen's plasma membrane and, when complete, puncture it.
Passive immunity can be obtained from __________.
an injection of antibodies that recognize invading microbes
The region of an antigen to which an antibody binds is termed the _____.
antigenic determinant
Helper T cells are part of _____.
cell-mediated immune responses
The proliferation of the B lymphocyte to which a specific antigen binds is referred to as _____.
clonal selection: When an antigen binds to a B cell or a T cell, that cell proliferates, forming clones of effector cells with the same specificity.
Which of the following is part of the inflammatory response?
dilation of the capillaries
Natural killer cells _____.
do not attack microorganisms directly; instead, they destroy virus-infected body cells and cancer cells
Antigen
foreign molecule that evokes an immune response
Which of the following cell types does HIV preferentially infect?
helper T cells
HIV attacks a certain type of T cell, thus causing _____.
immunodeficiency Helper T cells play a central role in immune system functioning, stimulating both B cell and T cell function. Chronic HIV infection depletes the helper T cell population and renders the immune system incapable of responding to infections.
Chemicals produced by virus-infected cells that alert neighboring cells to prepare a defense are called _____.
interferons
As an allergy sufferer, _____ are some of my least favorite cells.
mast cells The histamines produced by mast cells are responsible for much of the misery in my life.
What can white blood cells do that helps them carry out their defensive functions more effectively?
migrate into and out of blood vessels
The role of cytotoxic T cells is to attack _____.
mostly virus-infected cells, and tissues infected by bacteria or parasites, cancer cells and foreign cells introduced by blood transfusion or organ transplant
Plasma cells _____.
multiply and make antibodies that circulate in blood and lymph B cells that make antibodies are called plasma cells.
Functions of the lymphatic system include _____
return of fluid to the circulatory system and fighting infections
The immune system is initially capable of mounting responses to particular microorganisms because _____.
the body contains an enormous diversity of white blood cells, each with a specific kind of antigen receptor
During a secondary immune response, _____.
the generation of effector cells begins with memory cells produced during the primary immune response
The biggest difference between the cell-mediated immune response and the humoral immune response is _____.
the location of the pathogens they respond to
Cytotoxic T cells kill infected body cells by _____.
using perforins to make holes through which apoptosis-inducing chemicals can enter
