Anatomy and Physiology Answer Key

2 specific resistance refers to defense against

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Unformatted text preview: d Antigen Antibody type Heart size increases because (like any muscle) it gets bigger with work. The larger size also means it pumps a greater volume of blood more efficiently. 4. Self-recognition is undesirable: – During pregnancy. Note: Some features of the self-recognition system are disabled to enable growth (to full term) of what is essentially a large foreign body. – During tissue and organ grafts/transplants from another human (allografting) or a nonhuman animal (xenografting). Note: Such grafts are usually for the purpose of replacing rather than repairing tissue (e.g. grafting to replace damaged heart valves). For these grafts, tissuetyping provides the closest match possible between recipient and donor. The self-recognition system must also be suppressed indefinitely by immunosuppressant drugs. Anatomy and Physiology 2. (b) This self-recognition system allows the body to immediately identify foreign tissue e.g. a pathogen, and mount an immune attack against it for the protection of the body’s own tissues. 22 contrast, non-specific resistance refers to defense against any type of pathogen. 3. Anatomy and Physiology 4. 5. The leukocytes (white blood cells) involved in the second line of defense are the monocytes (which mature as macrophages) and the granulocytes (eosinophils, neutrophils, and basophils), so-called because of the granular appearance of their cytoplasm. Their roles are: – Eosinophils produce antimicrobial substances, including proteins toxic to certain parasites. Eosinophils also show some phagocytic properties. – Basophils release heparin (an anticoagulant) and histamine which is involved in inflammation and allergic reactions. – Neutrophils and macrophages are phagocytic, actively engulfing and destroying foreign material (e.g. bacteria). Functional role for (b)–(i) as follows: (b) Destroys pathogens directly by engulfing them. (c) Trap pathogens on sticky mucus and cilia move the trapped microbes out towards the mouth & nostrils. (d) Some secretions (sebum) have a pH...
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