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Anatomy 2 - Immune
The Immune System
37
Science
02/12/2011

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Term
What is innate immunity?
Definition
natural immunity: immunity to disease that occurs as part of an individual's natural biologic makeup
Term
What is adaptive immunity?
Definition
The adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic challenges. 
Term
What cells are utilized in the innate immune system?
Definition

Natural killer cells, mast cells, eosinophils, basophils; and the phagocytic cells including macrophages, neutrophils and dendritic cells, and function within the immune system by identifying and eliminating pathogens that might cause infection.


Term
What are the cells of the adaptive immune system?
Definition

1.B lymphocytes (B cells)—humoral immunity
2.T lymphocytes (T cells)—cell-mediated immunity
1.Antigen-presenting cells (APCs)
Do not respond to specific antigens
Play essential auxiliary roles in immunity

Term
Compare & contrast humoral & cell-mediated immunity
Definition

Comparison: humoral immunity is effected by antibodies produced by plasma cells toward a specific foreign antigen.

cellular immunity does not directly involve antibodies, but refers to cellular destruction of alien
cells/tissues by production of cytotoxins locally, typically the latter are produced by T-lymphocytes and natural killer cells

 

Contrast: In humoral immunity, the bodys lymphocytes produce antibodies, which bind to antigens and label it for destruction... In a sense the body is attacking from a distance, making antibodies and sending them out... In Cell mediated, the cells patrol the body directly (like the police) looking for bad cells and destroy them directly... they do not produce antibodies

Term
Describe humoral response
Definition
humoral response
- two stages, clonal selection & clonal expansion
- clonal selection
- B cells has an antibody receptor that is specific to the shape of antigen that has entered the body.
- clonal expansion
- selected B cells divides by mitosis, producing plasma cells & memory cells.
- plasma cells secretes antibodies that specifically combine with the antigen
Term
Describe cell-mediated response
Definition
 pathogen is taken in by macrophage
- macrophage process the pathogen & present their antigen on MHC protein.
- T helper cells attached to antigen & secretes cytokines to stimulate B lymphocytes to produce plasma cells to secretes antibodies.
Term
What are natural killer cells? (NK)
Definition

Large granular lymphocytes present in blood & lymph
Induce apoptosis in cancer cells & virus-infected cells
Secrete chemicals that enhance inflammatory response

Term
What is inflammatory response?
Definition

Triggered whenever body tissues are injured or infected (physical trauma, heat, chemicals, etc)
Functions:
Prevents spread of damaging agents
Disposes of cell debris & pathogens
Sets the stage for repair 

Term
What are the mediators of inflammatory response?
Definition

•Inflammatory mediators
•Histamine (from mast cells)
•Blood proteins
•Kinins, prostaglandins (PGs), leukotrienes, & complement
•Released by injured tissue, phagocytes, lymphocytes, basophils, and mast cells

Term
What is a fever?
Definition

Systemic response to invading microorganisms
Leukocytes & macrophages exposed to foreign substances secrete pyrogens
Pyrogens reset the body’s thermostat upward
Benefits of moderate fever:
Causes liver & spleen to sequester iron & zinc (needed by microorganisms)
Increases metabolic rate, which speeds up repair

Term
What are antigens?
Definition

Substances that can mobilize adaptive defenses & provoke an immune response
Most are large, complex molecules not normally found in body (nonself)
Simply, intruders that are the target of an immune response. 

Term
What are haptens?
Definition

Incomplete antigens.

 

Small molecules (peptides, nucleotides, & hormones)
Not immunogenic by self, but become so when attached to body proteins
Ex: poison ivy, animal dander, detergents, cosmetics

Term
What are antibodies?
Definition

Immunoglobulins —gamma globulin portion of blood
Proteins secreted by plasma cells
Capable of binding specifically with antigen detected by B cells
5 classes

Term
What are the classes of antibodies?
Definition

 

IgM - first antibody released
IgA (secretory IgA) –in mucus & other secretions
Helps prevent entry of pathogens
IgG – most abundant (75–85%)
Can cross placental barrier
IgE - active in some allergies & parasitic infections

 

Term
What is the iga antibody class?
Definition
Found in mucosal areas, such as the gutrespiratory tract and urogenital tract, and prevents colonization by pathogensAlso found in saliva, tears, and breast milk.
Term
What is the igD antibody class?
Definition
Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. It has been shown to activate basophils and mast cells to produce antimicrobial factors.
Term
What is the igE antibody class?
Definition
Binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy. Also protects against parasitic worms.
Term
What is the igG antibody class?
Definition
In its four forms, provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to fetus. The most abdundant.
Term
What is the IgM antibody class?
Definition
Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very high avidity. Eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there is sufficient IgG.
Term
What are the four types of organ transplants?
Definition

1.Autografts: from 1 body site to another in same person
2.Isografts: between identical twins
3.Allografts: between individuals who aren’t identical twins
4.Xenografts: from another animal species (eg pig hearts, valves, etc.)

Term
How does a cytotoxic t cell kill?
Definition

1. It binds tightly to the target cell when it identifies foreign antigen on MHC I proteins.

2. It releases perforin (A protein in killer cells and natural killer cells that causes lysis of target cells on contact.)

 and granzyme (serine proteases that are released by cytoplasmic granules within cytotoxic T cells and natural killer cells. Their purpose is to induce apoptosis within virus-infected cells, thus destroying them) molecules from its granules by exocytosis.

3. Perforin molecules insert into the target cell membrane, polymerize, and form transmembrane pores (cylindrical holes) similar to those produced by complement activation.

 

4. Granzymes enter the target cell via the pores. Once inside, these proteases degrade celullar contents, stimulating apoptosis.

5. The T cell detaches and searches for another prey.

Term
What is an interferon?
Definition
An antiviral protein produced by cells that have been invaded by a virus; inhibits replication of the virus in infected cells.
Term
What are immunodeficiencies?
Definition

Congenital & acquired conditions that cause immune cells, phagocytes, or complement to behave abnormally
Ex. AIDS, Hodgkin’s disease

Term
What are autoimmune diseases?
Definition

Immune system loses ability to distinguish self from foreign
Production of autoantibodies & TC cells that destroy body tissues
Exs: multiple sclerosis, myasthenia gravis, Graves’ disease, type I diabetes mellitus, systemic lupus erythematosus (SLE), & rheumatoid arthritis

Term
What are hypersensitivities?
Definition

Immune responses to a perceived (otherwise harmless) threat
Causes tissue damage
Different types are distinguished by time course & whether antibodies or T cells are involved
Antibodies cause immediate & subacute hypersensitivities
T cells cause delayed hypersensitivity 

Term
What are the differences between auto immune, immunodeficiency, and hypersensitivity?
Definition
auto immune disorders are when your cells forget what is foreign and attacks anything in your body. immunodeficiency is when cells forget how to protect the body against invaders. hypersensitivity is when your cells go crazy against harmless things such as allergens and can damage tissue.
Term
What is the origin of T cells and B cells?
Definition
They form in bone marrow. T cells leave and mature in the Thymus. B cells stay and mature in bone marrow.
Term
What is immunological memory?
Definition
a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide range of pathogens irrespective of antigenic specificity. Other components of the immune system adapt themselves to each new disease encountered and are able to generate pathogen-specific immunity.
Term
What are the four types of T cells?
Definition

Helper T-cells 

Killer T-cells 

Suppressor T-cells 

Memory T-cells 

Term
What is a helper T-cell?
Definition

 assist in both CMI and AMI. They secretelymphokines (cytokines) which are hormones that stimulate other cells in the body to resist invading antibodies. They display the protein CD4 on their surface;

Term
What is a killer T-cell?
Definition
They kill antigens directly once stimulated by agents released by the helper T-cells. They display the protein CD8 on their surface.
Term
What is a suppressor T-cell?
Definition
a controversial cell that is believed to dampen or suppress the immune response
Term
What is a memory T-cell?
Definition
They recognise the original invading antigen. When the antigen returns thousands of memory cells are available to initiate a far swifter reaction than occurred during the first invasion.
Term
What is a helper T cell? The importance and what would happen without it?
Definition

Play a central role in the adaptive immune response
Help activate T & B cells
Induce T & B cell proliferation
Activate macrophages & recruit other immune cells
Without TH, there is no immune response
Without an immune response, the body would have an immunodeficiency disorder.

Term
What are the steps in cell mediated response?
Definition

1.Antigen is engulfed and presented by a macrophage.

2. T cells with specific receptors recognize the antigen.

3. Several cycles of mitosis occur.

4. T cells differentiate into cytotoxic T cells or T memory cells.

5. Cytotoxic T cells migrate to focus of infection.

6. Cytotoxic T cells release perforin and/or lymphotoxin.

Term
Definition