Immunity Pt 2 Flashcards
Define pathogen and what is meant by communicable, contagious, and vector
Disease causing micro-ogranism
-communicable/infectious/ and transmissible
Communicable disease-disease passed from one person to another by infection with micro-organisms (also called infectious/transmissible)
Contagious- disease passed on by direct human contact
Vector-agent such as insect capable of transferring a disease-causing organisms from one person to another
Define bacteria. How to reproduce? Pathogenic or not?
Examples
prokaryote, cell wall, lack organelles and nucleus
-binary fission reproduction
-non-pathogenic
-Cholera, Chlamydia, Whooping cough, meningitis
Define virus and it’s structural characteristics. How to reproduce? Pathogenic or not?
Examples
Small, infectious agentl protein sheath surrounding core of nucleic acid;
-depend on living cells to reproduce
-pathogenic
-HIV, AIDS, bird flu, chicken pox
How do pathogens transmit x6 and quick explanation
(direct or indirect for each)
-By contact: direct or indirect physical
-Ingestion: contaminated food/drink
-Transfer of body fluids: blood to mucous membrane contact
-Infection by droplets: breathing, talking, coughing, etc
-Airborne transmission: dehydrated particles
-Transmission by vectors: by animals, insects, ticks, or mites
Difference between specific vs non-specific defences
Specific: defence of the body directed against a specific pathogen e.g. B and T cells
Non-specific: defence of the body that acts against all pathogens e.g. external and internal defences
What are the external non-specific defences x4
-skin: physical barrier
Sebum: oily secretion that kills some pathogenic bacteria
Sweat: salts + fatty acids that prevent bacteria growth
-mucous membranes : Line body cavities that open to exterior. Goblet cells produce the mucus which traps particles
e.g., digestive, urinary, reproductive tracts protected by mucus in nose, lungs, etc
-cilia: tiny beating hair like projections, found in nasal cavity+trachea, move trapped particles in mucus to throat to cough
-hairs: found in nasal cavity to trap particles
Bottom three aid respiratory protection
What are chemical external non-specific defences x3
Acids: Stomach: gastric acids that kill bacteria in food
Vagina: secrete lactic acid reduce growth of micro-organisms
Sweat glands: slightly
Urine: slightly
Lysozyme: Enzyme that kills bacteria. Found in most body fluids and cerumen (protects outer ear against infection by some bacteria, it is slightly acidic earwax)
Fluid movement: flushing action urine and tears
What are the internal defences x4
phagocytosis, fever, inflammatory response, lymphatic system
What are three main types of phagocytes/APC’s (add explanation)
Describe phagocytosis and add diagram
Cellular process for ingesting and eliminating particles
-neutrophils: lifespan few days, make up pus that forms after infection, destroy via phagocytosis
-dendritic cells: use info about ingested particles to assist with specific immunity
-macrophages: mono differentiate into macro once entering tissues
Meaning of itis. Define purpose of inflammation and it’s signs
(it’s non-specific)
itis=inflammation of specific organs/tissues
purpose: reduce spread of pathogens, remove damaged tissue and cell debris, begin repair of damaged tissues
signs: redness, swelling, pain, heat
Define whole process of inflammatory response
(7 steps)
- damage or chemical change will cause mast cells or WBC’s to activate and release histamine and heparin
- Histamine ^blood flow via vasodilation=excess heat loss via radiation/redness due to blood pigment. Also ^permeability of capillaries=more fluid to site of infection=swelling
- Other chemicals released by mast cells attract phagocytes and stimulate pain receptors
- Phagocytes begin to die=pus
- New cells produced via mitosis to repair tissue
reduce spread of pathogens, remove damaged tissue and cell debris, begin repair of damaged tissues
Define fever, e.g.
how it occurs
role of pyrogens
benefits
Elevated body temperature. Body’s thermostat is set at higher temperature (39)
1.macrophage is activated and releases pyrogens (e.g. interleukin-1)
2.pyrogens act on the hypothalamus to increase the set point
3.causes body to produce heat (e.g. shivering, vasocon.)
4.when fever breaks, normal set point re-established
benefits:
-inhibits some microbe growth
-inhibits virus replication through release of interferon
-speed up chem. reactions in body
What does lymphatic system; function and how it differs to circulatory system
-function:macrophagespick up bacteria from tissue, bacteria in lymph, forced to percolate through lymph nodes. There, white blood cells (lymphocytes) attack and kill bacteria.
-differ: lymph vessels are blind ended, unidirectional and absorbent circulatory are none.
What is the immune system composed of
Different types of cells that occur in most organs of the body and that protect against foreign organisms, alien chemicals and abnormal cells.
Define immune response. Function? What are the two part of response?
Homeostatic mechanism triggered by entrance of foreign substances or microorganisms into body (body doesn’t recognise protein)
Helps deal with invasion and restore internal environments to normal condition.
-humoral response/antibody-mediated immunity (B cells)
-cell-mediated response (T cells)
Explain how B-cells and T-cells get their names
Both are produced in the bone marrow and end up in lymphoid tissue. Half the cells go to thymus to mature into T cells before being incorporated into lymphoid tissue. Other half mature in bone marrow to become B cells then become part of lymphoid tissue.
Explain what an antigen is providing some examples.
Substance capable of causing an immune response
e.g. virus particles, bacteria (whole/part), toxins, molecules on cells=blood, pollen, egg whites
What are antibodies and examples? Explain what is meant by an antigen-antibody complex
-Y-shaped protein produced by plasma cells in response to non-self antigens. Belong to group of proteins=immunoglobulins (Ig)
-Antibody produced in response to antigen can combine to antigen to form the complex.
-possible as antigens contain active sites that have specific shapes and combine w/a complimentary antibody=lock and key model
What are antigen presenting cells (APC) and examples?
Immune cells that detect antigen presence, engulf, and inform immune response about infection.
e.g. dendritic cells. macrophages, B cells
Distinguish between the primary and secondary responses in the immune reaction
Primary/humoral response involved production/release of antibodies into blood and lymph. Provides resistance to viruses, bacteria, bacterial toxins before their entrance into body’s cells
Secondary response- provides resistance to intracellular phase of bacterial and viral infections unlike the humoral response.
Describe the process of antibody mediated immunity
Works against before entrance. Production of antibodies by B cells which circulate body and attack invading antigens
1.APC recognise, engulf (phagocytosis), and digest pathogens that bind to MHCll to be displayed as antigen on their surface
2.APC present antigen to specific B cells and T helpers
3.B cell becomes ‘sensitised /activated, T helper cells releases cytokines that activate more B cells
4.activated B cells enlarge+ divide, producing clones
5.most B cells become plasma cells that secrete antibodies to circulate blood, lymph + extracellular fluid
6.antibodies combine w/specific antigens to form antigen-antibody complex and destroy/inactivate non-self-antigens
7.remaining clones become memory cells that remain in lymphoid tissue allowing more rapid response to infection
List the ways in which antibodies can act to inactivate antigens
-inactivate by combining w/them or inhibiting their reaction w/other cells
-bind to surface of viruses+prevent cell entrance
-coat bacteria increase edibility by phagocytes
-(agglutination) increase edibility
-dissolves organisms
-make soluble toxins insoluble increase edibility
What is a benefit of memory cells to antigen exposure
Remain in lymphoid tissue and recognises antigen more quickly = faster response to exposure. Antibody levels will therefore rise rapidly to a higher level that lasts longer
increase antibody concentration decreasing time taken for second immune response in comparison to the first=less symptoms
Describe the process of cell mediated immunity
Works post-infection. Formation of special lymphocytes (T cells) that destroy invading cells
1.APC recognises, engulf (phagocytosis) + digest pathogen that binds to MHCll to be displayed as antigen on surface
2. APC present antigen to specific T cells
3. cytokines (released by t helper cells)stimulate T-cells to form clones after being sensitised, enlarging and dividing
4. most become Helper T-cells or Killer T-cells which migrate to infection site
5. Killer T-cells attached and destroy antigen by releasing cytotoxins that destroy membrane
6. Helper T-cells secrete substance that attracts more macrophages/increase macrophage activity
7. other clones=memory cells that remain in lymphoid tissue
9. Suppressor T cells derived from Killer T-cells secrete cytokines to signal lymphocytes to reduce activity = inhibiting B and T cells
What are the types of immunity
(draw as table)
Passive:
Natural-antibodies enter bloodstream across placenta or in breast milk
Artificial-antibodies are injected into blood stream
Active:
Natural-ability to manufacture antibodies results form an attack of a disease
Artificial-ability to manufacture anti-bodies results from being given antigen by vaccination
What form of immunity is longer lasting between natural and artificial? Why?
Natural. Longer lasting as memory cells are produced w/antibody production.
Define vaccine
How does immunisation differ
the artificial introduction of antigens to a person so that they acquire immunity without suffering illness
Immunization-programming immune system so that the body can respond rapidly to infecting micro-organisms
Describe each of the four types of traditional vaccines with an example of an associated disease
Live attenuated microorganisms:
Alive microorganisms. Decrease ability to produce disease symptoms e.g. polio, rubella, yellow fever, measles, mumps, tuberculosis
Inactivated:
Dead microorganisms. Shorter lasting immunity. e.g. cholera, typhoid, whooping cough
Toxoid:
Inactivated toxins from bacteria (toxoids) e.g. diphtheria and tetanus
Subunit :
Fragment of the organisms is used in antigen e.g. HPC and Hepatitis B
Outline the problems associated with traditional vaccines
Social: use of animals//human tissue to produce vaccines, informed consent, testing on animals, availability, increase concerns of promoting sexual activity in teens
Cultural: religious beliefs
Economic: cost of vaccine, commercialisation
Define antibiotics. Limitations?
Drugs used to fight infections of micro-organisms/bacteria
Cannot treat viral infections
What are the 4 types of antibiotics/explanations
Broad spectrum: affect many types of bacteria
Narrow spectrum: affect particular type of bacteria
Bacteriostatic: treat infections by stopping reproduction
Bactericidal: treat infections by killing bacteria
Define antiviral
drug used for treatment of viral infections specifically
antibiotics are ineffective
Define infection
invasion by and multiplication of pathogenic microorganisms within the body
Define leucocyte
white blood cells involved in protecting against infectious disease and foreign invaders
Define phagocyte
leucocytes that engulf/digest microorganisms+cell debris that are also capable of carrying out phagocytosis
What are the ways in which macrophages function?
-move through tissues looking for/destroying pathogens.
-fixed , dealing with pathogens that come to them. Particularly important in removing microbes and dying cells through phagocytosis.
Distinguish between self and non-self antigens
Self-antigens are large molecules produced in own body. Nonself-antigens are foreign compounds that do trigger a response
Define “agglutination”
Clumping together of microorganisms/cells
Give the additional importance of cell-mediated immunity
Also important in fighting whole cells, such as providing resistance to fungi and parasites, and in rejecting foreign-tissue transplants. Also in fighting cancer cells.
Explain what a “sensitized” T cell is
T cell that has been presented with antigen via the APC. The T cell is stimulated by cytokines released by helper T cells that cause it to become sensitised, enlarging and dividing.
