Micro_Chap24 – Flashcards
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Unlock answers| Immunity |
| Ability of an organism to resist infection |
| Where do all cells involved in immunity originate from? |
| Stem cells in bone marrow |
| What does the Immune system do? |
| protect against foreign cells and macromolecules |
| Antigen/ immunogen: |
| foreign cell or macromolecule that induces immune system |
| types of immunity? |
naturally acquired immunity artificially acquired immunity |
| Naturally acquired active immunity: |
host produces antibodies & T cells - can last from years to life time |
| Naturally acquired passive immunity: |
-when antibodies are passed from one host to another ex. antibodies through placenta from mother to fetus. -lasts few weeks to months |
| Artificially acquired active immunity: |
-result of vaccination -host makes antibodies that can last for years. |
| what do vaccinations/ immunizations contain? |
1. toxoid 2. killed bacteria cell 3.inactivated virus 4. live cells 5. purified polysaccharide |
Toxoid
ex.? |
chemically modified exotoxin retains antigenicity but loses toxicity.
ex. Tetanus, Diphtheria |
Killed bacteria cell
ex.? |
formaldehyde, heat
ex. Cholera (dead Vibrio cells) |
Inactivated virus
ex.
|
Formaldehyde
ex. Salk polio vaccine, influenza |
live cells/ virus
ex.
|
attenuated: has lost its virulence
ex. Tuberculosis, chicken pox most effective way
|
Purified polysaccharide
ex.
|
from the bacterial cell
ex. Meningitis |
| Artificially acquired passive immunity: |
Host receives antibodies (antiserum) from another host that has formed antibodies against a specific antigen -snakebite victim -lasts only few weeks |
Phagocytic leukocytes do what? (neutrophils & macrophages + monocytes) |
engulf and destroy pathogens contains lysosomes (inclusions contain H2O2, lysozyme, proteases, phosphatases, nuclease, and lipase) |
Neutrophils aka |
| PMNs --polymorphonuclear leukocytes |
Macrophages and monocytes when is it called a monocyte? what does a macrophage do? |
- called monocyte when circulating -differentiates into macrophage when enters tissues -Macrophage: antigen presenting cell > presents peptide antigens to T cells to activate a specific immune response. |
| Adaptive immunity: |
Immune system reacts to specific antigens (foreign proteins, sugars, chemicals) -retains "memory" of these antigens
|
| Humoral Immunity: |
production of antibody proteins -each binds different antigens |
| Cellular immunity: |
T cells that bind different antigens -kill pathogens, control antibody production |
| Immunogenicity: |
| Ability of antigen to elicit immune response. |
| What is an ex. of a good antigen? |
Proteins: b/c they are fixed and nonrepetitive shape |
Immune reaction is specific. blood types: type A attacks type B blood cell antigen AB blood has both antigens, won't make antibodies ; |
| Antigen Presenting Cell (APC) |
| Phagocytic cells that present processed antigens to T cells. |
Antibody (Immunoglobin) what is it? produced by what? interacts with what? |
| A soluble protein produced by B cells; interacts with antigen |
| After ingestion of a pathogen, what happens with phagocytes and B cell lymphocytes? |
| phagocytes and B cell lymphocytes present antigens on the surface to T cell lymphocytes |
| The ingestion of the pathogen results in? |
Cell mediated immunity; or Antibody mediated / Humoral immunity |
| Cell mediated immunity involves? |
| T cell lymphocytes |
| What does T cell lymphocytes do? |
| Mainly protects against tumor cells and virus-infected cells |
| Where are T cells derived from? |
| ;Bone marrow stem cells |
| Where do these stem cells migrate? |
| to the Thymus |
| In the thymus, what do these stem cells do? |
| differentiate into T lymphocytes. |
| When phagocytes digest pathogens, _____ from pathogen are bound to the surface of phagocyte. |
| polypeptides |
| What happens when an APC binds to a T cell? |
| the T cells differentiate |
What are the major classes of T cells? ; |
1. Helper T cells (h1,h2,h0) 2. Cytotoxic T cells 3. Memory T cells 4. T cell receptors |
| Th1: |
| activates Tc cells |
| Th2: |
| Binds B cells ; activates them to divide into plasma and memory cells |
| Th0: |
| Undifferentiated T cells |
| Cytotoxic T cells |
Destroy tumor cells and infected cells by releasing cytotoxin - also recognizes grafted tissues ; organs as foreign |
| Memory T cells |
| allows host to respond to 2nd exposure quickly |
| T cell receptors |
| receptor that binds antigen specifically. |
| Structure? |
2 peptides (alpha ; beta) each with constant and variable domain |
| which structure binds the antigen? |
| Variable domains |
| Major Histocompatibility Complex proteins |
| "self" proteins on surface of cells |
| What does MHC proteins do? |
| bind to antigen |
| T cell receptors recognizes ______ |
| antigen/ MHC protein |
| Class 1 MHC proteins on surface of all nucleated cells presents what? |
| intracellular antigens to Tc cells |
| Class 2 MHC proteins on surface of antigen-presenting cells presents what? |
| Extracellular antigens to Th cells |
| When do T cells become activated? |
| When antigen/ MHC binds to T cell receptor |
| T cell; T cell receptor; Peptide antigen (epitope); MHC protein; antigen presenting cell |
| Tc cells destroy what? |
| Antigen presenting cell |
| Th1 cells do what? |
| recruit macrophages to destroy antigen bearing cell. |
| What are attacked by the Th1 cell activated macrophages? |
tumor cells transplanted organs tissues |
When antibodies bind to antigens, they _____them. ; |
| inactivate |
| antibodies are most active against |
| bacteria, bacterial toxins, and viruses in blood stream |
What do antibodies recognize if not the entire pathogen? ; |
| regions called Epitopes. |
| binding of an antibody does not directly kill the cell. |
Antibody binding: 1. activates _____ system 2. Enhances __________ 3. causes _________ 4. neutralizes _______ |
1. complement 2. phagocytosis 3. agglutination (clumping together) 4. antigens |
| Complement system |
| group of proteins that act together to enhance immune system |
Complement can: 1. increase _______ 2. Attract and activate _______ 3. cause _______ |
1. inflammation 2. phagocytes 3. lysis |
| Opsonization |
process of enhancing phagocytosis by binding both to a microbe and phagocyte, bringing them closer in proximity. |
| what region allows each fragment to bind antigen independently? |
| Hinge region |
| Antibody structure? |
| Y shaped protein |
IgG consists of how many polypeptide chains? ; |
| 4 |
| The 2 large/ heavy chains are identical ; held together by; |
| 2 disulfide bonds |
| The 2 small/ light chains are also identical and held together by; |
| 1 disulfide bond |
| Antibody has Constant and Variable domains. |
| What region does the antigen bind? |
| Variable regions |
| Each IgG can bind 2 antigens. |
| What defines the class of antibody? |
| The heavy chain in the constant domain |
| 5 classes of antibody: |
IgG IgA IgM IgE IgD |
| IgG |
Most abundant- 80% of Ig in serum Only antibody that can be transferred through placenta Gamma heavy chains |
| IgA |
Predominant antibody in secretions (saliva, tears, milk, mucus.) Dimer Alpha heavy chain |
| IgM |
2nd most abundant; 1st class of antibody made in response to infection Aggregate of 5 molecules attached by disulfide bonds ; J chain protein can bind up to 10 antigens Mu heavy chains ; |
| IgE |
Low concentrations, responsible for allergies binding of antigen to IgE causes release of histamine (allergies) Epsilon heavy chain |
| IgD; |
Found on the surface of B cells Binding of antigen to these antibodies stimulates B cells to produce antibody IgG Delta heavy chains. |
| B cell is a type of ? |
| Lymphocyte that makes antibodies |
| Where are B cells made and matured? |
| in bone marrow |
B cells disperse through: ; |
| blood and lymph |
| B cells collect in: |
| Lymph nodes and spleen. |
| 1st step in making antibodies |
b cell must phagocytize foreign cell so that polypeptides from that cell are bound onto B cell surface. ; |
| 2nd step to make antibodies |
| Th cell binds to the polypeptide on B cell, this triggers B cell to divide. |
B cells differentiate into: ; |
| Plasma cells and memory cells |
Which antibody is made first, then what? ; |
| IgM first, then IgG |
| Isotope switching/ class switching |
| Predominant antibody produced becomes IgG instead of IgM |
Immune response diseases ; |
Hypersensitivities ; super antigens |
| Hypersensitivity type 1 |
results from 2 or more exposures to same allergen 1st exposure - B cell produce IgE; IgE binds mast cells and basophils 2nd exposure - Mast cells and basophils release histamine |
Histamine produces what?; causes what? ; |
produces prostaglandin, leukotrienes causes allergy symptoms. |
| anaphylactic shock |
constriction of airways and drop in blood pressure ; |
treatment for allergies: ________ to neutralize histamine ________ to reduce inflammation ___________ to counter effects of histamine ____________- allergy shots that shift antibody production from IgE to IgG |
1. antihistamines 2.steroids 3. adrenalin 4. desensitization |
Type II Hypersensitivity: antibodies bind to foreign ________ antigen -blood transfusion recipients -Rh- mother has antibodies to Rh+ fetus -can occur within hours |
| cell surface |
Type III hypersensitivity: antibodies bind to ________antigen -large amounts of antigen- antibody complex are formed -triggers complement cascade -stimulate mast cells -in response to certain antibiotics -can take weeks to occur |
| soluble |
| Type IV-Delayed type hypersensitivity |
result of sensitivity to chemicals or microbes Th1 cells release cytokines that activate macrophages, NK cells, and Tc cells takes few days to occur typical antigens: M. tuberculosis; chemicals that covalently bind to skin creating new antigens symptoms: hardening swelling, reddening pain and localized heating |
| type 2 hypersensitivity autoimmune diseases |
autoantibodies Rheumatic fever hemolytic anemia Graves disease Myasthenia gravis |
| autoantibodies |
| antibodies that interact with self antigens, destroying self-molecules |
| Rheumatic fever |
Autoantibodies to cardiac cells, damages heart valves caused by similarity between epitope in M protein of Streptococcus pyogenes and cardiac tissue --(antigenic mimicry) |
| hemolytic anemia |
| autoantibodies to Rh blood group; destroys RBC |
| Graves disease |
| Autoantibodies to thyroid stimulating hormone receptor causing hyperthyroidism |
| Myasthenia gravis |
autoantibodies to acetylcholine receptor; causes progressive muscle weakness
|
Type III diseases : antibodies bind soluble proteins, creating insoluble complex leading to complement and inflammation |
Rheumatoid arthritis Systemic lupus erythematosis |
| Rheumatoid arthritis |
| complexes deposited in joints; inflammation & destruction of cartilage |
| Systemic lupus erythematosis |
| complexes deposited in kidney, lungs, & spleen |
type IV autoimmune diseases : T cells respond to self antigens |
Multiple sclerosis Type 1 diabetes |
| Multiple sclerosis |
T cells attack myelin protein, destroying covering of neurons
|
| type 1 diabetes |
t cells attack insulin producing cells in pancreas; preventing insulin production |
super antigens: proteins that can cause very strong immune response, activate more T cells than normal -bypass normal route of antigen processing by binding TCR &MHC -results in cytokine production, systemic inflammation. |
Toxic shock syndrome Scarlet fever |
Toxic shock syndrome
|
| staphylococcus aureus super antigen exotoxin |
| Scarlet fever |
| Streptococcus pyogenes super antigen erythrotoxin |
