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AP Biology - Immune System
Terms in this set (73)
break down bacterial cell walls
-white blood cells
-engulf pathogens in that actually get into the body
TLR or Toll-Like Receptors
-found on the surface of white blood cells-recognize pathogens
-binds fragments of molecules characteristic to a set of pathogens, phagocytosis and destruction is triggered
Types of Phagocytic Cells
engulf and destroy microbes
develop into macrophages-larger phagocytic cells
cells involved in innate response
neutrophils, monocytes, dendritic cells, eosinophils, natural killer (NK) cells, interferons, complement system
populate tissues, like skin, that contact the environment
discharge destructive enzymes to destroy multicellular parasites
Natural Killer (NK) cells
recognize and release chemicals that destroy pathogens
Antimicrobial peptides and proteins
interferons and complement system
-proteins that provide innate defense against viruses and help activate macrophages
-secreted by virus-infected body cells-allowing nearby cells to inhibit viral reproduction
-about 30 proteins that become activated by microbes which causes lysis of invading cells and helps trigger inflammation
pain and swelling brought about by signaling molecules released upon physical injury or entry of pathogens
parts of inflammatory response
mast cells (release histamine), cytokines
release histamine which trigger blood vessel dilation and permeability so phagocytes can enter tissues
-signaling molecules that promote blood flow to the area resulting in red and warmer temperature
-this aids in delivering clotting agents and phagocytic cells to the injured area
Adaptive immunity parts
lymphocytes, antigens, antigen receptor, antibodies, MHC, effector cells, memory cells
white blood cells that recognize and respond to antigens, foreign molecules
lymphocytes that mature in the thymus are
foreign molecules that are recognized by a B or T cell
When a B or T cell binds to an antigen, how does recognition occur?
the small accessible part of an antigen that binds to an antigen receptor
soluble form of receptor proteins (not anchored) secreted by B cells during an immune response. DEFENDS AGAINST PATHOGENS
What initiates B cell activation?
The lock and key fit is initiated by the binding of a B cell antigen receptor to an antigen.
Difference between binding of T cells and B cells
Unlike B cells, T cells only bind to fragments of antigens that are presented or displayed on the surface of a host cell
Major Histocompatibility Complex (MHC) molecule
-host protein that displays the antigen fragment
-recognition for T cells
MHC molecules bind and transport the antigen fragments to the cell surface. A T cell can then bind both the antigen fragment and the MHC molecule
4 major characteristics of adaptive immune system
-diversity of lymphocytes and receptors, self-tolerance; lack of reactivity against an animal's own molecules, proliferation of B and T cells after activation, Immunological memory
-the specificity of B and T cells results from the shuffling and recombination of gene segments
-more than 1 million different B cells and 10 million different T cells
-since antigen receptors are generated by random rearrangement of DNA, they may produce receptors that match the organism's own molecules
-as lymphocytes mature, they are tested for self-reactivity
-Lymphocytes with receptors specific for the body's own molecules are destroyed y apoptosis, or are nonfunctional
How are B and T cells proliferated, and what specifically is produced?
-Effector Cells and Memory Cells are specifically produced
-short-lived and act immediately against the antigen
-B cells: plasma cells
-T cells: helper T and cytotoxic T cells (killer T cell)
once activated, a B or T cell undergoes multiple cell divisions to produce a clone of identical cells
long-lived that can give rise to effector cells if the same antigen is encountered again
Memory cells are responsible for long-term protections against diseases, due to a prior infection
Primary Immune Response
-first exposure to a specific antigen and a lymphocyte is activated
-Selected B and T cells multiply in there to their effector and memory forms
-Effector: Plasma Cells (B cells) and Cytotoxic T and Helper T cells
Secondary Immune Response
same antigen is encountered again-memory cells facilitate a faster, stronger, and longer response
Adaptive Immunity's Two Branches
Humoral immune response and Cell-mediated immune response
Humoral immune response
effector B cells secrete antibodies to help neutralize or eliminate toxins and pathogens in the blood and lymph
Cell-mediated immune response
involves activation and clonal selection of specialized Cytotoxic T cells that identify and destroy infected host cells
What branches of adaptive immunity do Helper T cells help with?
What responses do cell-mediated immune response enables?
Primary and secondary
Helper T cells
trigger both the humoral and cell-mediated immune responses
-signals that are then exchanged between the helper T cells and antigen-presenting cell (body's immune cells)
-activate helper T cells, stimulate division and activate Cytotoxic T and B cells
Cytotoxic T cells
-effector cells that bind to infected body cells that display antigen fragments and destroy them
-trigger secretion of toxic proteins that disrupt membranes of target cells and trigger apoptosis
Humoral response is associated with B or T cells? What else?
B cells and antibodies
characterized by secretion of antibodies by B cells to destroy extracellular pathogens
In humoral response, how is activation of B cells aided
cytokines and helper T cells
What does clonal selection of B cells in humoral response generate?
plasma cells, the effector cells of humoral immunity
Do antibodies kill pathogens?
No, they mark pathogens for destruction or neutralize them.
-develops naturally in response to an infection (or artificially with vaccination)
a nonpathogenic form of a microbe or part of a microbe elicits an immune response to an immunological memory
-provides immediate, short-term protection and occurs when an individual receives antibodies produced by someone else
-does not last long
Passive Immunity Natural Example
antibodies passed to the fetus across the placenta or infants via milk
Passive Immunity Artificial Example
snake bite. Can inject antibodies from an immune animal into a non immune animal.
cells transferred from one person to another can be attacked by the recipient's immune defenses if recognized as "foreign"
Red Blood Cells
A, B, AB, or O antigens
How do physicians minimize rejection when dealing with blood transfusions and the transplant of tissues or organs?
They use donor tissue that closely matches the MHC molecules of the recipient.
Does Blood type O have antigens?
Blood type O
exaggerated hypersensitive responses to antigens called allergens
-for localized allergies, plasma cells secrete antibodies specific for antigens on the surface of pollen grains, which triggers immune cells in connective tissue to release histamine which causes the symptoms of allergies (so many allergy medicines are called anti-histamines)
an acute allergic response can lead to this life-threading reaction. Many people with these hypersensitiveness often carry epinephrine to counteract the allergic response.
-the immune system loses tolerance for self and turns against certain molecules of the individual's own body.
Examples of autoimmune diseases
lupus, rheumatoid arthritis, insulin-dependent diabetes mellitus, and multiple sclerosis
Immune system avoidance
mechanisms ot thwart immune responses have evolved in pathogens
When a pathogen alters how it appears to the immune system by changing the epitopes it expresses. This mechanism is seen in the parasite that causes sleeping sickness and in the influenza virus.
some viruses can avoid an immune response by infecting cells and entering this inactive state. Ex: herpes simplex and herpes zoster. Stimuli include stress, fever, or menstruation
-People with AIDS are highly susceptible to infections and cancers that take advantage of an immune system in collapse.
-The spread of HIV is a worldwide problem.
-The best approach for slowing this spread is education about practices that transmit the virus.
-Treatments for AIDS have been slow to be developed because the virus mutates.
Cancer and Immunity
-the frequency of certain cancers increases when adaptive immunity is impaired
-the immune system can act as a defense against viruses that cause cancer and against cancer cells that harbor viruses
-20% of all human cancers involve viruses
-in 2006, a vaccine was released that acts against human papilloma virus (HPV), a virus associated with cervical cancer
What percentage of human cancers involve viruses?
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