Study sets, textbooks, questions
Upgrade to remove ads
43 - Immune System
Terms in this set (59)
Innate immune Response:
- Found in all animals.
- Leukocytes respond nonspecifically way to pathogens.
Adaptive immune response:
- Known only for vertebrates.
- Lymphocytes responding to specific pathogen antigens.
- Agents causing disease.
- Capable of infecting wide range of animals.
- Recognizes foreign bodies.
- Responds with production of immune cells/proteins.
- Resistance to/protection against disease-causing pathogens.
- Prevents individuals from contracting diseases multiple times.
Innate immune response:
- Relies on common traits of pathogen groups.
- Found in all animals.
- Chitinous exoskeleton forms first pathogen barrier.
- Chitin-based barrier protects digestive system by:
- Lysozyme (enzyme) breaks down bacterial cell walls.
- Cells synthesize/secrete potent antibacterial/antifungal peptides.
- Circulate within hemolymph.
- Phagocytize foreign substances including bacteria:
- Ingestion/digestion (inserts lysosome's digestive enzymes into vacuole containing pathogens).
- Presents physical/chemical barriers (e.g. low pH).
Skin barrier gaps occur:
- Digestive tract
- Reproductive tract
- Respiratory surfaces
- Sensory organs
Protective physical barrier for gaps:
- Mucus—proteoglycan-rich solution secreted by epithelial cells
- Ear wax •
- Lysozyme—occurs in tears
- Despite preventative measures: pathogens can gain entry to subcutaneous tissues.
- Type of connective tissue
- Release histamine:
- Triggers blood vessel dilation
- Triggers blood vessel permeability
- Engulf/destroy pathogens
- Found throughout body
- Recruit other cells
- Engulf/destroy pathogens
Toll-like receptors (TLR) =
pattern-recognition receptors: Membrane receptors (some mammalian innate system cells).
- Pathogen-specific surface compounds activate them.
- Not on host cells
- "On" switches for cell response.
- Each mammalian TLR recognizes molecular pattern - characteristic of of pathogen group (bacteria/virus/fungus):
- CpG DNA (DNA with unmethylated CG sequences)
- Double-stranded (ds) RNA
Mammalian inflammatory response:
- Local or systemic.
- Multi-step innate immune response.
- Occurs at injury site.
Steps of process:
1. Skin breaks/pathogens enter wound.
2. Platelets release blood-clotting proteins at wound site.
3. Wound site tissues/macrophages secrete chemokines.
- Signaling molecules recruiting immune cells by forming gradient marking site pathway.
4. Mast cells release blood vessel constricting chemical messengers near wound:
- Reduces blood flow/blood loss.
5. Mast cells secrete histamine/other signaling molecules: dilating blood vessels farther from wound:
- Increasing permeability.
5. Neutrophils/macrophages remove pathogens by phagocytosis:
- Engulf/digest foreign particles.
6. Macrophages secrete cytokines:
- Chemicals attract other immune system cells to site.
- Activate tissue repair cells.
- Induce fever (systemic response) via pyrogens elevating body temperature aiding healing.
8. Inflammatory response eliminates foreign material/wound repaired.
- Pyrogens released by macrophages/pathogens.
- Septic shock—life-threatening/ overwhelming inflammatory response.
Adaptive immune response = acquired immune response based on interactions between:
- Specific immune system cells
- Specific antigens
Four key adaptive immune response characteristics:
- Adaptive immune system components bind only specific sites on specific antigens.
- Adaptive response recognizes nearly limitless antigen array.
- Adaptive response reactivated quickly if previous infection antigens recognized.
4. Self-non-self recognition:
- Molecules produced by individual body cells ≠ antigens.
Lymphocytes formed/matured/ activated/transported in distinct immune system components :
1. Lymphocytes mostly produced in bone marrow.
2. Also originate in spleen.
- Lymphatic organ in abdominal cavity.
3. B cells mature in bone marrow.
4. T cells mature in thymus after migrating from bone marrow.
5. Lymphocytes recognize antigens/become activated in spleen/lymph nodes.
6. Lymphocytes circulate through blood/secondary organs of immune system.
- lymph nodes
- lymphatic ducts
- Thin-walled/branching/lymhatic system tubules transporting lymph throughout body.
Large numbers of lymphocytes associated with:
- Skin cells
- Mucus secreting epithelial tissues primarily in:
- Digestive tract
- Respiratory tract
- Called mucosal-associated lymphoid tissue (MALT).
- Guard points of entry against pathogens.
Lymphocytes normally in inactive state.
- Inactive lymphocytes have:
- Large nucleus
- Little cytoplasm
- Few mitochondria
- Ruffled membrane
If lymphocyte does encounter appropriate antigen: becomes activated.
Activation produces dramatic lymphocyte changes.
Lymphocytes from bone marrow versus from thymus:
Bone marrow lymphocytes (B cells)
Thymus lymphocytes (T cells) involved in array of functions:
including recognizing/killing viral infected host cells.
Four central claims of clonal-selection theory:
1.Each lymphocyte bears thousands of unique membrane surface protein receptor copies recognizing only one antigen.
2. Lymphocyte bound to specific antigen = activated.
3. Activated lymphocyte divides/makes many identical copies because infection selected/cloned them.
4. Some activated lymphocyte descendent clones persist after pathogen eliminated - allows rapid response if infection recurs.
B-cell receptor (BCR)
protein on B cell surface binding antigens (= IgD).
other B cell produced antibodies
Three components of B-cell receptor:
1. Two identical light chains.
2. Two identical heavy chains (~twice light chain size).
3. Transmembrane domain within each heavy chain anchors B cell plasma membrane receptor.
Five classes of immunoglobulins:
1.IgG (2nd soluable class produced)
2. IgD (membrane bound)
3. IgE (soluable class)
4. IgA (soluable class)
5. IgM (1st soluable class produced)
Each class distinguished by:
- Its heavy chain constant region.
- Distinct immune response function.
T-cell receptor (TCRs) surface proteins bind antigens:
1. Antigens processed by other immune system cells.
2. Displayed on plasma membranes of other cells (antigen presentation).
- B cells bind antigens directly.
- T cells bind only to other cells displaying antigens.
TCR = two protein chains
- Alpha (α) chain
- Beta (β) chain:
- Both shaped similar to BCR short "chain."
- selected antigen region binding antibodies/BCRs/TCRs
- Each epitope recognized by particular antibody/BCR/TCR.
- Antigen can often bear 10 - 100 different epitopes.
Different B cell BCRs/antibody light chains/heavy chains have:
1. Common segment: constant (C) region.
2. Unique segment for each of B cell type: variable (V) region.
TCRs also bear variable region near ends of both protein chains.
Unique/highly variable BCR/TCR amino acid sequences allow binding to their unique epitopes.
When dendritic cells arrive at wound:
1. Dendritic cells ingest antigens present at wound.
2. Antigen enters membrane-bound compartment inside cell.
3. Enzyme complex breaks proteins into pieces/bind to MHC protein.
4. MHC-antigen complex transported to cell surface.
5. MHC-antigen complex displayed on cell surface.
T lymphocyte activation begins:
- Dendritic cell/infected cell takes up antigens.
- T cell interacts with dendritic cells within lymph organs.
- Antigen cut into pieces.
- Packaged with specific cell proteins (MHC).
- Transferred to cell surface.
- Antigen-presenting cells interact with T cells
- T cells bind presented antigens via TCR/begins activation process.
Two types of T lymphocytes classified as CD8+ or CD4+:
- CD4 or CD8 accessory proteins on plasma membranes.
- CD8+ T cells (killer T cells) interact with MHC-class-I-bound antigens.
- CD4+ cells (helper T cells) interact with MHC-class-II-bound antigens.
Antigen-presenting cell carries message - activating T cell:
"I've found antigen—response required."
Activated T cells undergo clonal expansion
- Divide producing series of clones.
- Antigen response produces large lymphocyte population.
Activated CD8+ T cells undergoing clonal expansion
- Cytotoxic T cells (killer T cells).
- Cytotoxic T cells interact only with host body cells displaying MHC Class I protein bound antigens.
- Signals infected cell ➜ sacrifice itself.
- Body cells displaying MHC class I protein bound antigen sends cytotoxic T cell message: "Kill me."
Activated CD4+ T daughter cells become helper T cells:
help other lymphocytes activate
Helper T cells interact with MHC Class II protein-bound antigen presenting lymphocytes:
found on B cell
Lymphocytes displaying MHC class II protein bound antigen sends message to helper T cells:
B-cell activation involves four steps:
1. B cell encounters/binds foreign protein in lymph node/spleen ➞internalizing/processing/presenting molecule on cell surface MHC Class II protein.
2. Antigen complex interaction with helper T cell receptors ➜ B cell activation of helper T cell.
3. Activated helper T cell releases cytokines (chemical messengers) activating B cell.
4. Activated B cell divides: some daughter cells differentiating into: Short-lived plasma cells producing large quantities of antibodies.
- Long-lived memory cells responding rapidly to additional antigen exposure.
Antibodies specific to pathogen:
- circulate in blood
- bind to antigens
- mark them for destruction
Antigen-antibody complexes bind complement proteins:
Triggers complement protein cascade activation (membrane attack complex).
Two major ways adaptive immune system eliminate viruses:
1. Cell-mediated response•Involves cytotoxic T cells (activated CD8+ cells)
- Occurs at infected cell's surface.
2. Humoral response.
- Involves antibodies
- Occurs in blood/lymph.
- MHC class I bound viral antigen displaying cell recognized by activated CD8+ T cells (cytotoxic T cells).
- Bind to virus-infected cell•Produce cell membrane pores
- Activates self-destruct response
Cell-mediated response prevents new generations of virus particles from maturing.
- Viruses reproduce only inside host cells.
- Limits spread of infection.
Antibodies coat free virus particles preventing cell infection
Antibodies bound to viral exterior allows:
1. Virus blocked from infecting host cells.
2. Macrophages/other phagocytic cells recognize antibody-coated particles ➜phagocytize them.
- Virus population reduced to zero.
To prevent strong immune reactions - physicians:
1. Obtain transplanted organ from sibling/other donor where MHC proteins extremely similar to recipient (tissue-typing).
2. Treat with drugs suppressing immune response
- No participation by memory cells in primary immune response.
- Provide secondary immune response if same antigen re-enters body.
- Circulating memory cells ↑ likelihood lymphocytes with correct antigen-specific receptors activate quickly.
- Secondary response faster/more efficient than primary response.
- ↑ Memory cell receptor binding ability for antigen's epitope = somatic hypermutation.•Fine-tunes immune response.•Memory cells with best binding receptors: live//produce daughter cells.
- Those binding antigen less effectively: die.
- Somatic hypermutation produced antibodies:
- Bind faster/better than antibodies from plasma cells arising from primary immune response.
Three types of vaccines:
1. Subunit vaccines: (e.g. hepatitis B/influenza) = isolated viral proteins.
2. Inactivated viruses: (e.g. hepatitis A/polio) damaged by chemical treatments/exposure to ultraviolet light.
- Antigenic without causing infections.
3. Attenuated ("live") viruses: (smallpox/polio/measles) complete virus particles unable to rapidly grow in host cells.
- After vaccination:
- Primary immune response produces memory cells.
- Later occurring second infection allows memory cells quick response /eliminates before illness appears.
abnormal over-reactive antigen response.
potentially lethal reaction occurring from severe allergic immune response.
Recommended textbook explanations
Campbell Biology (AP Edition)
Cain, Campbell, Minorsky, Reece, Urry, Wasserman
Biocalculus: Calculus for the Life Sciences
Modern Biology: Student Edition
Janet L. Hopson, Postlethwait
Biocalculus: Calculus, Probability, and Statistics for the Life Sciences
Sets found in the same folder
Bio Midterm II
biology 1111 exam 4
42 - Circulation and Gas Exchange
44 - Osmoregulation and Excretion
Sets with similar terms
BIOL 3200 "Adaptive Immune Response" (Exam 4)
AP Bio Ch 43 Vocab
Mastering Biology Ch. 43 The Immune System
Other sets by this creator
Common Ions You Need to Know
Definitions for Midterm 1
BIO LAB 1111 - MIDERM 1
Biology 1111 Lab Midterm with Alternativ…
Other Quizlet sets
Ic exam chapter 12
anatomy and physiology
Historical & Monarchy Books