Term
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Definition
| An organism or virus that causes disease. |
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Term
| Explain why antibiotics are effective against bacteria but not viruses. |
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Definition
- antibiotics block specific metabolic pathways found in bacteria, but not eukaryotic cells
- because viruses reproduce using the host cell (eukaryotic) metabolic pathways, the are unaffected by antibiotics
- antibiotics have produced great benefits world-wide in the control of bacterial diseases
1. Staphylococcus infections controlled
2. STD's, such as gonorrhea and syphilis controlled
- antibiotic resistance has evolved in bacterial populations |
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Term
| Outline the role of skin and mucous membranes in defence against pathogens. |
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Definition
- 1st line of defence = nonspecific
- skin:
. tightly bound barrier of dead, keratin-rich epidermal cells
- tough, elastic, waterproof surface
. sebum: oily secretions from sebaceous gland in hair folicle, preventing skin cracking
. inhibits growth of pathogens
- mucous membranes:
. linings of intestinal tract, respiratory tract, eyes, genitals
. mucous traps microbes
. lysozymes: antibacterial enzymes
. cilia: clear respiratory tract
. acidity:
- stomach: pH = 2
- vagine pH = 5-6 |
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Term
| Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissues. |
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Definition
- damage to tissues allows invasion across 1st line of defence:
. microbes successfully invade body fluids or tissues
. damaged cells release histamine and other chemicals initiating inflammation
- phagocytes attracted to site by chemotaxis toward histamine
. phagocytes recognize microbes as foreign by antigen recognition
. variety of phagocytic cells: neutrophils (65% of WBCs), monocytes (4% of WBCs), macrophages (derived from monocytes)
- phagocytes endocytotically engulf microbes in phagosomes, which are digested by enzymes held in lysosomes
. digested microbe fragments are displayed on cell membrane
. phagocytes with microbe fragments displayed = antigen-presenting cells: APCs |
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Term
| Distinguish between antigens and antibodies. |
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Definition
- antigen: a molecule recognized as foreign by the immune system; it elicits an immune response
- antibody: = immunoglobulin
. a globular protein
. recognizes an antigen by its complementary shape and charge
. thus allowing it to attach to the antigen specifically
. marking it for attack by the immune system |
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Term
| Explain antibody production = Humoral rseponse. |
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Definition
- macrophages:
1. following phagocytotic digestion, display antigen on surface
2. becoming antigen-presenting cells = APCs
- macrophage APCs activate helper T-lymphocytes
1. only T-lymphocytes with receptor proteins specifically matching the antigen of the APCs
- B-lymphocytes activated by helper T-lymphocytes
1. only those B-lyphocytes with antibodies specifically matching helper T-lymphocytes receptor proteins are activated
- clonal selection of activated B-lymphocytes
1.produces a large population of B-lymphocytes
. plasma cells
. memory cells
- B-lymphocyte plasma cells produce massive quantities of antibodies (1000s/sec)
1. by protein synthesis
2. releasing antibodies by exocytosis
3. into the surrounding humors
. blood
. tissue fluids
- antibodies adhere to antigens
1. marking them for phagocytosis by macrophages
- memory lymphocytes specific to the pathogen remain in elevated quantities
1. B-lymphocytes and helper T-lymphocytes
2. reside in the lymph nodes
3. upon subsequent exposure to the antigen
. produce a rapid and intense response
. = secondary response |
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Term
| Outline the effects of HIV on the immune system. |
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Definition
- reduction in the number of active lymphocytes
- loss of the ability to produce antibodies |
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Term
| Discuss the cause, transmission and social implications of AIDS. |
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Definition
- disease: AIDS
- cause: HIV: human immunodeficiency virus which attacks the CD4 cells of the immune system
- transmission:
. sexually transmitted (vaginal, oral, anal)
. interstitial fluid
. blood-borne (transfusion, mother/child: placenta or breast milk, contaminated needles)
- social implications:
. the vast majority of cases are in Africa, with rapid increases in Asia
. changes in sexual behaviour
. unease over blood transfusions
. ostracizing PWA
. breakdown of family structure
. huge drain on medical resources
. huge loss in work force
. drugs are available to control effects of HIV, but cost is high
. poor families have limited resources, and are impoverished by the cost of drugs;
. poor nations have little drug availability
- moral implications:
. do those with technology and wealth have an obligation to help others lacking such resources? |
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