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38 Cards in this Set

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Define pathogen
an organism or virus that causes a disease
Why are antibiotics effective against bacteria but not viruses?
antibiotics block specific metabolic pathways found in bacteria; viruses reproduce using the host cell's metabolic pathways, which are not affected by antibiotics
Outline the role of the skin in defence against pathogens
The skin is an external, nonspecific defense against pathogens. It is a physical barrier which, if damaged, must be repaired by blood clotting. It is also a chemical barrier because it produces waxes (making it harder for the pathogen to enter) and sweat (which can injure pathogens).
Outline the role of the mucous membranes in defence against pathogens
The skin is an nonspecific defense against pathogens. It is a physical barrier which. It is also a chemical barrier because it produces mucus, which makes it harder for the pathogen to enter.
What do phagocytic leucocytes do?
They ingest pathogens in the blood and body tissues by phagocytosis (make sure you know what that is). Once the phagocytic leucocytes/macrophages ingest the pathogen, they break it down using the enzymes in their lysosomes. Antigens are displayed on the surface in an MHC protein; at this point you can call the cell an antigen-presenting cell. It will travel to the lymph node to stimulate helper T cells
Define antigen
Substances (molecules) which can stimulate the production of antibodies. Pathogens have many types of antigens on their cell surface (often membrane proteins or carbohydrates). Keep in mind that human cells also have antigens. We recognize our own antigens as "self." If you get a transplant or a blood transfusion from another human with different antigens then your immune system will respond to that new tissue/blood.
Define antibody
A Y-shaped protein that recognizes and binds to specific antigens. (Make sure you understand the difference between antigen, antibody, and antibiotic…don't mix them up!)
Explain antibody production
IB topic 6: "Many different types of lymphocytes exist. Each type recognizes one specific antigen and responds by dividing to form a clone. This clone then secretes a specific antibody against the antigen." IB topic 11 adds more: Macrophage ingests pathogen and presents antigen on MHC protein. Antigen-presenting cell goes to lyph node and activates helper T cells (only the helper T cells that can help fight the disease are activated; those cells divide rapidly; "clonal selection"). Helper T cells activate B cells (clonal selection). Some of these differentiate into plasma cells, which produce antibodies; others differentiate to become memory cells.
What do helper T cells do? How are they activated?
Activate B cells and cytotoxic T cells. Activated by antigen-presenting cells/macrophages/phagocytic leucocytes by clonal selection.
What do B cells do? How are they activated?
B cells differentiate into plasma cells and memory cells (see other flashcards). Activated by helper T cells and antigen .
What do plasma cells do? Where do they come from?
They secrete antibodies. They are a type of B cell (undifferentiated B cells divide during clonal selection and then differentiate into plasma cells and memory cells)
What do memory cells do? Where do they come from?
They allow your body to respond very quickly (lots of antibodies made really fast) the NEXT time you are exposed to the pathogen.. They are a type of B cell (undifferentiated B cells divide during clonal selection and then differentiate into plasma cells and memory cells)
What do cytotoxic cells do? How are they activated?
Kill virus-infected cells and cancerous cells. Activated by helper T cells and antigen .
If you have a bacterial infection, what specific defences let you kill it?
Antibodies are good against extracellular pathogens and toxins. You want to state this and explain how you produce antibodies (see other flashcards)
If you have a viral infection, what specific defences let you kill it?
Cytotoxic T cells are good against intracellular viruses. You want to state this and explain how you produce cytotoxic T cells (see other flashcards)
What are some internal, non-specific defenses?
Fever, inflamation, phagocytosis by macrophages
What is a polyclonal response?
When multiple types of antibodies are produced. This is the case when you are infected with a pathogen because it has multiple types of antigens on its surface
What is a monoclonal antibody?
antibodies produced artificially that bind to one type of antigen only
How are monoclonal antibodies made?
1)      Fuse together a tumor cell and a B-cell a) B-cells produce antibodies (you’ll need the one that makes the specific type of antibody you want) b) Tumor cells divide rapidly and cell lines descended from them tend to live longer 2) Hybrid cell will proliferate 3) Hybrid cells will produce antibodies, which you can use in diagnosis and treatment
What are some uses of monoclonal antibodies in treatment?
Targeting cancer cells with drugs attached to monoclonal antibodies; Emergency treatment of rabies or snake bite; Purification of industrially made interferon; Destroying T cells to reduce the rejection of transplants
What are some uses of monoclonal antibodies in diagnosis?
Pregnancy testing (antibody to human chorionic gonadotropin (HCG))…uses ELISA; HIV testing (antibodies to look for antibodies against HIV)…uses ELISA; Heart attack diagnosis (antibodies to look for a specific cardiac isoenzyme)…uses ELISA; Blood and tissue typing for transplant compatibility; Testing for (different strains of) malaria
Define active immunity and give examples
immunity due to the production of antibodies by the organism itself after the body’s defense mechanisms have been stimulated by antigens”; immunity due to disease or vaccination
Define passive immunity and give examples
"immunity due to the acquisition of antibodies from another organism in which the active immunity has been stimulated” ; antibodies through placenta to baby, antibodies in colostrum (breast milk) to baby, injection of antibodies (like snake anti-venom)
Define natural immunity and give examples
immunity due to infection or acquisition from mother; from having a disease yourself and making your own antibodies, antibodies to fetus through placenta, antibodies to baby in breast milk
Define artificial immunity and give examples
immunity due to vaccination (or other non-infectious process); immunity due to vaccination or injection of antibodies (ie snake anti-venom)
If you get sick with a disease once (or get a vaccine) why are you immune from getting it again?
You have made memory cells! They allow your body to respond very quickly (lots of antibodies made really fast) the NEXT time you are exposed to the pathogen. Make sure you can draw/label the graph that illustrates this idea!
What is clonal selection and where do you see examples of it in the immune response?
clonal selection: a small number of lymphocytes are activated and divide rapidly to produce a clone of cells which are all effective against the particular pathogen your body is fighting; Helper T cells (activated by macrophages), B Cells (activated by helper T cells), Cytotoxic T cells (activated by helper T cells)
Explain the principle of vaccination
1) Inject patient with vaccine which contains a)inactive toxins, fragment of pathogen, killed pathogen, weakened pathogen or weakened pathogen/attenuated virus…you don’t want the person to get sick from the vaccine b)Possibly preservatives or something left over from production process (like egg) 2) Patient’s macrophages will ingest and present antigens 3) Helper T cells bind to macrophages and are activated (clonal selection) 4) Antigen binds to B cells. Then, Helper T cells bind to B cells and activate them by clonal selection (lots of mitosis!). Some are plasma cells that make antibodies to deal with whatever was in the vaccine. Some of these differentiate into memory cells. A)The key thing to note is the role of the memory cells. Now that the patient has memory cells, if he/she is ever infected with the real disease with the same antigens he/she can have a fast secondary response and therefore not experience the symptoms of illness. A graph is ideal to show this B)Second booster shots are somet
What are benefits of vaccination?
Some diseases, such as small pox, can be totally eliminated*; Prevention of epidemics and pandemics*; Decreased health care costs* (particularly with respect to decreasing disability—blindness, paralysis, etc); Prevention of harmful side-effects of disease* (Rubella in pregnant women can lead to deafness and blindness in the baby; Mumps can cause infertility in men); Deaths can be prevented, ex. from measles. ; Reduce job absenteeism; Disease free cattle/more food; Healthier society (Items with a * are required by IB)
What are dangers of vaccination?
Possible side effects of mercury in vaccines * (Mercury is used in some vaccines to kill bacteria present in certain vaccines and preserve others from bacterial contamination; Mercury effects: Effects brain development and cognition (larger effect of developing nervous systems of fetuses and children. Also affects functioning of glomerulus in kidney. ;There are now some mercury-free vaccines); Possible overload of immune system * (Excessive amounts of vaccination may reduce the ability of the immune system to cope with new diseases.); Possible links with autism * (MMR (measles, mumps, and rubella) vaccine can increase the chance of autism according to some sources. This may be linked to the use of mercury); Immunity developed after vaccination may not be as effective as immunity due to the actual disease. ; Pregnant women, cancer patients, and others can be harmed by cross-infection from people vaccinated with the live virus, ex. smallpox vaccine. ; Allergic reactions; People with compromised immune system
What is HIV?
the virus that causes AIDS (human immunodeficiency virus)
What is AIDS?
the disease caused by HIV (Acquired Immunodeficiency Sydrome)
What is the cause of AIDS?/ How does AIDS effect the immune system?
Caused by HIV; causes low number of helper T cells; therefore, less B cells are activated and less antibodies are produced; this causes the body to become more vulnerable to pathogens (people with AIDS die from secondary infections or rare cancers that they can't fight off)
How is AIDS transmitted?
Transmission involves transfer of body fluids; HIV does not live outside the body; Sexual intercourse (vaginal, anal or oral)(small cuts); Childbirth (through cuts w/blood); Through placenta and in breast milk (lower risk); Needle sharing (traces of blood on needles); Blood transfusion (safe in US); blood products/factor VIII used to treat hemaphiliacs (now considered safe in US)
What are the social consequences of AIDS?
Discrimination: Individuals with HIV may become stigmatized and not find housing, partners or employment; Cost of health care to countries/insurance; Families become poorer if the individual with AIDS was the wage earner and does not have/is refused life insurance. Reduction of workforce; Grief of family and friends ; Orphaned children…family structure/stability affected; Sexual activity in a population may be reduced because of the fear of AIDS (affects people of all ages, sexes, genders, sexual orientations, socioeconomic ststuses, etc)
Describe the process of blood clotting
Release of clotting factors from platelet results in the formation of thrombin (from prothrombin). Thrombin catalyzes the conversion of soluble fibrinogen into the fibrous protein fibrin, which captures blood cells (making a clot).
What sort of drugs are used against bacteria and viruses?
Antibiotics for bacterial infections; antivirals for viral infections
Do antibiotics and antiviral drugs give you immunity against a disease?
no