Immune System Flashcards
What are the components of the immune system?
Immunocytes (e.g. lymphocytes and macrophages) and a diverse array of molecules (e.g. antibodies and lymphokines)
What is the significance of the immune system?
It recognizes foreign antigens and acts to immobilize, neutralize, and destroy them.
What is one major shortcoming of the immune system?
It must be primed by an initial exposure to antigen before it is capable of protecting the body.
Where do immunocytes originate?
Hematopoietic Stem Cells (Bone Marrow)
What are the three types of of hematopoietic stem cells?
Erythroid, Lymphoid, Myeloid
Erythroid stem cells mature into _____.
Erythrocytes
Lymphoid stem cells mature into _____.
Natural Killer Cells, B-lymphocytes, and T-lymphocytes
Myeloid stem cells mature into _____.
Monocytes, Myeloid Progenitor, Basophils, Eosinophils, Neutrophils, and Mast Cells
Monocytes mature into _____.
Macrophages
Myeloid Progenitor matures into _____.
Megakaryocyte
This is the ability of the body to defend against infectious agents, foreign cells, and abnormal cancer cells.
Immunity
These do not distinguish between different kinds of pathogens.
First and Second Lines of Defense (Non-Specific Immunity)
This line of defense consist of natural/mechanical barriers.
First Line of Defense
The first line of defense consist of natural barriers such as _____.
Skin and Mucous Membranes
This part of the first line of defense inhibits the growth of bacteria on the skin.
Oil Secretions
This part of the first line of defense sweeps mucous and particles up into the throat to be swallowed.
Ciliated cells on the upper respiratory tract.
This attribute of the stomach inhibits the growth of many types of bacteria.
Low pH (1.2-3.0)
These prevent the colonization of pathogens in the intestine and vagina.
Bacteria that normally live in the intestine and vagina.
How many mechanisms does the second line of defense have?
Three
What are the mechanisms of the second line of defense?
- Phagocytic and Natural Killer Cells
- Localized Inflammatory Response
- Antimicrobial Proteins
These cells are attracted to damaged cells and are self-destructive.
Neutrophils
How do neutrophils defend the body?
They enter the infected tissue, and engulf and destroy the microbes there.
This refers to the migration towards the source of chemical attractant.
Chemotaxis
These transform to macrophages once they enter the affected tissue.
Monocytes
Unlike neutrophils, which only live for a few days, monocytes are _____.
Long-lived
These engulf microbe/s in a vacuole, fuse them with lysosomes, and kill them.
Macrophages
What is/are the mechanism of monocytes?
- Generation of toxic forms of oxygen (superoxide and nitric oxide); and
- Lysosomal enzymes to digest microbial components
These are macrophages found in the lungs.
Alveolar Macrophages
These are macrophages found in the liver.
Kuppfer Cells
These are macrophages found in the kidney.
Mesangial Cells
These are macrophages found in the brain.
Microglial Cells
These are macrophages found in the connective tissues.
Histiocytes
These are macrophages found in the spleen and the lymph nodes.
Fixed Macrophages
These cells defend the body from parasitic invaders.
Eosinophils
How do eosinophils defend the body?
By releasing destructive enzyme/enzymes targeting the parasite’s external wall.
Why are natural killer cells unique?
- They do not attack microbes but destroy virus-infected/abnormal cells
- They do not phagocytose but mount an attack via lysis of infected cell/s
How are natural killer cells different from cytotoxic killer T-cells?
- NK cells have no receptors and are non-specific;
- Are granulated; and
- Are not thyums dependent.
When does localized inflammatory response occur?
When there is damage to tissue or entry of microorganisms
What are the four symptoms of the inflamed area?
Redness, Pain, Swelling, and Heat
What is the first step of localized inflammatory response?
Release of bradykinin by capillary tissue cells of damaged tissue.
What is the second step of localized inflammatory response?
Nerve impulse to local pain receptor
What is the third step of localized inflammatory response?
Stimulation of mast cells to release histamine
What is the fourth step of localized inflammatory response?
Vasodilation and increased permeability of capillaries
What is the fifth step of localized inflammatory response?
Neutrophils and macrophages migrate to the site of injury and phagocytose microbes.
What is the physical/external manifestation of vasodilation?
Redness
This refers to squeezing through the capillary wall.
Diapedesis/Extravasation
This refers to the accumulation of dead neutrophils along with tissue cells, bacteria, and living WBCs.
Pus
When there is severe infection, what do leukocytes secrete?
Pyrogens
What do pyrogens do?
Increases Body Temperature (Fever)
What is/are the purpose/s of fever?
- Inhibits growth of some microorganisms
- Facilitates phagocytosis
- May speed up the repair of tissues
This refers to high fever and low blood pressure caused by bacterial infection.
Septic Shock
This is an antimicrobial protein/enzyme present in tears, saliva, and mucous secretions.
Lysozyme
This is composed of 20 serum proteins that carry out a cascade of steps leading to lysis of microbes.
Complement System
These are secreted by virus-infected animal cells.
Interferons
How do interferons defend the body?
They bind to receptors of non-infected cells and induce them to produce substances (in large quantities in recombinant DNA technology).
How do complement systems work?
- Protein seals the invader.
- Protein attaches to invader and punctures the cell membrane.
- Protein attaches to invader and attracts the leukocyte.
This is the line of defense that has specific immunity and involves lymphocytes.
Third Line of Defense
These lymphocytes are for humoral immunity and are produced in the bone marrow.
B-cells
These lymphocytes are for cell-mediated immunity and are produced in the bone marrow but mature in the thymus.
T-cells
This refers to the response mounted my the immune system against pathogens or antigens.
Immune Response
What are the characteristics of immune response?
- Antigen-specific
- Systemic
- Has Memory
What does the antigen-specific characteristic of immune response mean?
It recognizes and directs its attack against particular antigens or foreign substances.
What does the systemic characteristic of immune response mean?
Immunity is not restricted to initial infection site.
This refers to a foreign molecule that elicits a specific response by lymphocyte.
Antigen
This is a portion of the antigen that has a particular molecular shape, and reacts with the antibody.
Antigenic Determinant
How is the immune system triggered by antigens?
It stimulates certain B-cells to secrete antibodies or stimulates T-cells to enhance attack on the infected cell.
When the antigenic determinant of the antigen reacts with the antibody, it forms _____.
Antibody-antigen Complex
The formation of the antibody-antigen complex ultimately leads to _____.
The Inactivation and Removal of the Antigen
What is clonal selection?
The antigen-driven cloning of lymphocytes
What activates a lymphocyte to clone its self?
Selection of a lymphocyte by one of the microbe’s antigens
When a lymphocyte is activated, it divides to produce _____.
Two Clones of Cells: Effector (Plasma Cells) and Memory Cells
What are plasma cells?
Derivatives of B-cells that secrete antibodies
What are memory cells?
A clone of long-lived lymphocyte that remains in the lymph node until activated by exposure to the same antigen that triggered its formation
This refers to the initial immune response to an antigen.
Primary Immune Response
What happens during the primary immune response?
Selective proliferation and differentiation of lymphocytes that occurs the first time the body is exposed to an antigen
This refers to the immune response elicited when an animal encounters the same antigen at some time later.
Secondary Immune Response
The secondary response is more _____, of greater _____, and of _____ duration.
Rapid, Magnitude, Longer
This refers to another does of the original vaccine given some time after the original dose is administered.
Booster Shot
What are the immune responses stimulated by a booster shot?
Large amounts of antibodies and memory cell, and better, longer-lasting immunity
What do the two main classes of MHCs do?
They mark body cells as “self”
These are MHCs present on all nucleated cells .
Class I MHC
These are MHCs present only in specialized types such as macrophages, B-cells, activated T-cells, and interior cells of the thymus.
Class II MHC
This is what happens when self tolerance fails.
Autoimmune Disease
This is the critical feature of the immune system wherein no mature lymphocytes react against cell components.
Self Tolerance
What happens to lymphocytes bearing receptors specific for molecules already present in the body?
They are either rendered non-functional or destroyed by apoptosis.
What is apoptosis?
Programmed Cell Death
This refers to a large set of cell-surface antigens encoded by a family of genes.
Major Histocompatibility Complex
What do foreign MHC markers do?
They trigger T-cell responses that may lead to rejection of transplanted tissues or organs.
These cells have receptors that bind to peptides displayed by the body’s class II MHC molecules.
Helper T-cells
These are cells with antigen receptors that bind with class I MHC molecules.
Cytotoxic T-cells
This refers to a glycoprotein that helps to connect helper T-cells to macrophages by binging to the MHC molecules.
CD4
This refers to a glycoprotein that helps to connect cytotoxic T-cells to cells displaying MHC molecules.
CD8
This refers to a type of lymphocyte that kills infected and cancer cells.
Cytotoxic T-cells
This refers to macrophages and B-cells that present degradation products (peptide remnants) to helper T-cells.
Antigen Presenting Cells
How do helper T-cells “help” B-cells?
They help B-cells make antibodies.
How do helper T-cells “help” T-cells?
They help them respond to antigens or secrete lymphokines or interleukins.
How do suppressor T-cells “suppress”?
- Prevention of further development of T-cells
2. Prevention of B-cells and T-cells from getting out of control
These are clones of long-lived B- or T-cells that are mobilized during secondary immune response.
Memory T-cells
What is the structure of an antibody?
Four polypeptide chains, with constant and variable regions, joined to form a Y-shape
What is the minimum number of binding sites that basic antibody subunit has?
Two
How many monomer units do IgMs have?
Five
How many monomer units do IgAs have?
Two
How many monomer units do IgGs, IgDs, and IgEs have?
One
This immunoglobulin is the first circulating antibodies to appear in response to an initial exposure to antigen.
IgM
What is the significance of the five monomer units of IgMs?
These provide numerous binding sites, which make it very effective.
This immunoglobulin is the most abundant of the circulating antibodies and readily crosses the walls of blood vessels and enters tissue fluids.
IgG
This immunoglobulin is produced by cells in mucous membranes and its main function is to prevent the attachment of viruses and bacteria to epithelial surfaces.
IgA
This immunoglobulin does not activate the complement system and cannot cross the placenta.
IgD
This immunoglobulin is found in many body secretions and helps protect the infant from gastrointestinal infections.
IgA
This immunoglobulin crosses the placenta and confers passive immunity to the fetus; it also triggers action of the complement system.
IgG
This immunoglobulin is mostly found on the surfaces of B-cells, functioning as antigen receptors that help initiate differentiation of B-cells into plasma/memory cells.
IgD
This immunoglobulin is slightly larger than IgG and represent only a small fraction of antibodies in the blood.
IgE
The tails of this type of immunoglobulin attach to mast cells and basophils, and cause cells to release histamine and other chemicals that cause an allergic reaction.
IgE
What are the four steps of the antibody-mediated disposal of antigens?
- Neutralization
- Agglutination
- Precipitation
- Lysis
What happens in the neutralization step of antibody-mediated disposal of antigens?
Antibodies cover the toxic sites of the antigenic agents
What happens in the agglutination step of antibody-mediated disposal of antigens?
Multiple antigenic agents are bound together into a clump by antibodies
What happens in the precipitation step of antibody-mediated disposal of antigens?
Complex of antigen-antibody becomes insoluble and precipitates
What happens in the lysis step of antibody- mediated disposal of antigens?
Some very potent antibodies are capable of directly attacking membranes and thereby causing rupture of cells
This refers to the immune response in which binding of antibody to the surface of a microbe facilitates phagocytosis of a microbe by a macrophage.
Opsonization
What is the role of helper T-cells in cell-mediated immune response?
- Produces Interleukin-1
2. Causes T-cells to multiply
What is the role of helper T-cells in humoral immune response?
- Binds to B-cell antigen complexes
2. Causes B-cells to multiply
This refers to the protein in insects that binds to microbes and assists in their disposal.
Hemolin
These refer to the amoeboid cells in echinoderms that phagocytose foreign matter.
Coelomocytes
This type of humoral immunity develops following exposure to antigen and the person’s body is the one that produces the antibody.
Active Humoral Immunity
This type of humoral immunity occurs when antibodies are supplied by an immune human or animal donor.
Passive Humoral Immunity
What happens when an allergen enters the body?
- B-cells develop into plasma cells that secrete IgE antibodies
- Some of these antibodies bind tails to mast cells
- Degranulation
- Release of histamine via cellular granules
How is degranulation triggered?
Allergen binds to IgE already on mast cell
This is an autoimmune disease in which there are autoantibodies against all sorts of self molecules.
Systemic Lupus Erythematous
This is an autoimmune disease that leads to damage and painful inflammation of the cartilage and bone of joints.
Rheumatoid Arthritis
This is an autoimmune disease wherein the beta cells of the pancreas are the targets of autoantibodies.
Insulin-dependent Diabetes
This is an autoimmune disease in which T-cells reactive against myelin infiltrate the CNS and destroy the myelin of neurons.
Multiple Sclerosis
This is an immunodeficiency disease wherein both branches of the immune system fail to function.
Severe Combined Immunodeficiency
This is an immunodeficiency disease that suppresses the immune system by damaging the lymphatic system.
Hodgkin’s Disease
