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48 Cards in this Set
- Front
- Back
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How do microbes and humans interact |
• Microbes are very abundant in the environmentand as well as in and on our bodies • We use microbes to make many foods and weeven use them to make drugs • Microbes are important as decomposers torecycle nutrients • Some microbes cause disease in humans, wecall these pathogens |
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Microbes |
Microbes are microscopic organisms andparticles that include: – Bacteria – Viruses – Prions – Others (fungi, multicellular parasites, single-celled protistans) |
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Bacteria |
• Prokaryotic cells • Single-celled • Almost all have a cell wall • Have DNA in a single chromosome • Have ribosomes • Some have accessory rings of DNA calledplasmids |
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Pathogens |
organisms such as viruses and bacteria that are capable of causing disease |
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Cocci, Bacilli, and Spirilli |
Cocci are spherical in shape, bacilli are rod-shaped, and spirilli are spiral shaped bacteria |
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Methicillin and Other "Cillin" Drugs |
are used against certain bacteria because they interfere with the production of the cell wall |
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Capsules |
exist in some bacteria and prevent them from being destroyed by phagocytic white-blood cells and certain one-celled organisms |
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Binary Fission |
This ability allows some species of bacteria, under ideal conditions, to double their numbers every 12 minutes |
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Bacterial Toxins |
Will be the cause of discomfort after eating from a salad bar |
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Plasmid |
an additional ring of DNA found in some bacteria |
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Viruses |
acellular, obligative parasites that contain a protein coat called a capsid may contain DNA or RNA as their genetic material are capable of multiplying in a host cell because viral DNA instructs the cell to produce more of the virus |
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Prions |
• Infectious proteinparticles • Cause degenerativedisease of thenervous system • Normal proteinschange their shape |
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4 Functions of the Lymphatic System |
• Lymphatic capillaries absorb excess tissue fluidand return it to the bloodstream • Lymphatic capillaries (lacteals) in the smallintestine absorb fats associated with proteins • Works in the production, maintenance anddistribution of lymphocytes in the body • Helps in defense against pathogens |
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Components of the Lymphatic System |
Tonsil Right Lymphatic Duct Red Bone Marrow Axillary Lymph Nodes Thymus Thoracic Duct Spleen Inguinal Lymph Nodes |
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Lymphatic Vessels
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• One-way valve system that carries fluid calledlymph • Made of capillaries, vessels and ducts • Function to return tissue fluid (includes water, solutes and cell products) to the bloodstream • The larger vessels are similar in structure toveins and even have valves |
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Two Classes of Lymphatic Organs |
Primary and Secondary |
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Primary Lymphatic Organs |
• Red bone marrow – Site of blood cell production – More bones in children have red marrow and itdecreases as we age – Some white blood cells mature here • Thymus gland – Bilobed gland found in the thoracic cavity superior to the heart – Largest in children and shrinks as we age – Immature T lymphocytes move from the marrow tothe thymus where they mature and 95% will stay |
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Secondary Lymphatic Organs |
• Lymph nodes – Small, oval-shaped structures found along thelymphatic vessels filled B cells, T cells andmacrophages – Common in the neck, armpit and groin regions • Spleen – In the upper left region of the abdominal cavity – Filled with white pulp containing lymphocytes and redpulp is involved with filtering the blood |
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What do the nonspecific defensesinclude? |
• First line of defense: – Barriers to entry: physical and chemical • Second line of defense: – Phagocytic white blood cells – Inflammatory response – Protective proteins: complement andinterferons |
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The First Line of Defense: Physical Barriers |
– Skin – Tears, saliva and urine physically flush out microbes – Mucous membranes line the respiratory, digestive, reproductiveand urinary tracts – Resident bacteria/normal flora that inhabit the body useavailable nutrients and space thus preventing pathogens fromtaking up residence |
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The First Line of Defense: Chemical Barriers |
– Secretions of the oil glands – Lysozyme found in saliva, tears and sweat – Acidic pH of the stomach and vagina |
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The Second Line of Defense: Phagocytic White Blood Cells |
• Includes neutrophils and macrophages • Both leave circulation and move into tissue • Cells that are important in the inflammatoryresponse |
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The Second Line of Defense: Inflammatory Response |
- Four hallmark symptoms are redness, heat, swelling and pain - Histamine is released by mast cells causes the capillaries to dilateand become more permeable including to phagocytic white bloodcells - Increased blood flow to an area increases the warmth that inhibitssome pathogens - Increased blood flow also brings more white blood cells to an injuredarea with neutrophils being the first scouts to kill pathogens - This response can be short-lived but if the neutrophils cannot controlthe damage cytokines (chemicals) will call in more white blood cellsincluding macrophages |
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The Second Line of Defense: Protective Proteins |
Complement : - Group of blood plasma proteins - Involved in the inflammatoryresponse by binding to mast cellsto release histamine - Attract phagocytes to pathogensby binding - Form a membrane attack complexthat make holes in some bacteriaand viruses that causes them toburst • Interferons: - Proteins produced by virallyinfected cells sent out to warmneighboring healthy cells |
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Third Line of Defense |
– Helps protect us against specific pathogens when nonspecific defenses fail – Helps protect us against cancer – Depends on the action of B and T cells(remember that these are lymphocytes) |
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B Cells |
Produce plasma cells and memory cells |
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Plasma Cells |
Produce specific antibodies |
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Memory Cells |
Ready to produce antibodies in the future |
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T Cells |
Regulate immune response produce cytotoxic T cells and helper T cells |
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Cytotoxic T Cells |
Kill virus-infected cells and cancer cells Have vacuoles containing granzymes and perforins Perforins punch holes intarget cells followed bygranzymes that cause thecell to undergo apoptosis |
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Helper T Cells |
Regulate immunity Secrete cytokines that helpmany immune cellsfunction |
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Memory T Cells |
Ready to kill in the future |
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Characteristics of B Cells |
Antibody-mediated immunity against pathogens Produced and mature in bone marrow Directly recognize antigen and then undergo clonal selection Clonal expansion produces antibody-secreting plasma cells as well as memory B cells |
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Third Line of Defense: Antibody-Mediated Immunity By B Cells |
- Each B cell has a unique receptor called a BCR that binds a specificantigen - This binding and cytokines secreted by helper T cells result in clonalexpansion in which this B cell makes copies of itself - Most of the cells produced are plasma cells that secrete antibodies - Other cells become memory cells which result in long-term immunity - After an infection has passed plasma cells undergo apoptosis(programmed cell death) leaving memory cells |
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Structure of Antibodies |
• A Y-shaped protein • The trunk of the Y is aconstant region thatdetermines the class ofthe antibody • The end of the arms (Y)are the variable regionswhere specific antigensbind |
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The 5 Classes of Antibodies |
IgG - Main antibody type in circulation; crosses the placentafrom mother to fetus - Binds to pathogens, activates complement, and enhances phagocytosis by white blood cells IgM - Antibody type found in circulation; largest antibody; first antibodyformed by a newborn; first antibody formed with any new infection - Activates complement; clumps cells IgA - Main antibody type in secretions such as saliva and milk - Prevents pathogens from attaching to epithelial cells in digestive and respiratory tract IgD - Antibody type found on surface of immature B cells - Presence signifies readiness of B cell IgE - Antibody type found as antigen receptors onbasophils in blood and on mast cells in tissues - Responsible for immediate allergic response and protectionagainst certain parasitic worms |
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Characteristics of T Cells |
Cell-mediated immunity against virus-infected cells andcancer cells Produced in bone marrow, mature in thymus Antigen must be presented in groove of an HLA (MHC) molecule Cytotoxic T cells destroy nonself antigen-bearing cells Helper T cells secret ecytokines that control the immune response |
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Third Line of Defense: Cell-Mediated Immunity by T Cells |
- Each T cell has a unique receptor called a TCR that will recognize apiece of an antigen with the help of an antigen-presenting cell (APC) - An APC engulfs an antigen, breaks it down and presents it on itssurface in association with a membrane protein called an MHC(called human leukocyte antigens in humans or HLA) then presentsit to T cells in the lymph node or spleen - The T cell will specifically recognize the combination of the HLAprotein and the piece of antigen - Clonal expansion will occur leading to mostly helper T cells,cytotoxic T cells and a few memory T cells - After an infection has passed, helper and cytotoxic T cells undergoapoptosis leaving memory cells |
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Immunity |
• Is the ability to combat diseases andcancer • Can be brought about naturally through aninfection or artificially through medicalintervention • There are two types of immunity: activeand passive |
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Active Immunity |
• The individual’s body makes antibodies against aparticular antigen • This can happen through natural infection or throughimmunization involving vaccines • Primary exposure is shorter-lived and slower to respondwhile a secondary exposure is a rapid, strong response • This type of immunity is usuallylong-lasting • It depends on memory B and T cells |
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Passive Immunity |
• An individual is givenprepared antibodiesagainst a particularantigen • This type of immunity isshort-lived • This can happen naturallyas antibodies are passedfrom mother to fetus orartificially via an injectionof antibodies |
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How do we make antibodies to be usedfor passive immunity? |
We make monoclonalantibodies (derived fromplasma cells that originatedfrom the same B cell) inglassware outside the body (invitro) This is done through fusion ofplasma cells with myelomacells that allow them to divideindefinitely This fusion results in a cellcalled a hybridoma |
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How can the immune system react thatmaybe harmful to the body? |
• Allergies • Tissue rejection • Immune system disorders |
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Allergies |
• Hypersensitivities to harmless substances such aspollen, food or animal hair • An immediate allergic response is caused by the IgEantibodies that attach to mast and basophils. Whenallergens attach to these IgE molecules histamine isreleased and we see allergy symptoms. • An immediate allergic response that occurs when theallergen enters the bloodstream is anaphylactic shock inwhich the blood pressure drops and is life-threatening • Delayed allergic responses are initiated by memory Tcells such as seen with poison ivy |
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Tissue rejection |
• This can occur when cytotoxic T cells respond totissue that is not recognized as “self” tissue • This can be controlled by giving patientsimmunosuppressive drugs and by transplantingorgans that have the same MHC proteins in thedonor and recipient • Currently we are trying to grow organs in the labthat can be transplanted with less rejection |
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Disorders of the Immune System |
Autoimmune diseases and Immunodeficiency dieases |
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Autoimmune Diseases |
– A disease in which cytotoxic T cells or antibodies attack the body’s own cells as if they were foreign – Examples: multiple sclerosis, lupus, myastheniagravis and rheumatoid arthritis |
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Immunodeficiency Diseases |
– A disease in which the immune system iscompromised and thus unable to defend the bodyagainst disease – Examples: AIDS and SCID |
