Anatomy and Physiology Answer Key

B although the fev1fvc ratio is reduced in asthmatics

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Unformatted text preview: omes scarred, less flexible, and thicker. This reduces the amount of alveolar expansion possible and reduces the diffusion efficiency across the gas exchange surface. 4. Many restrictive diseases are caused by inhalation of dusts and pollutants associated with particular occupations, e.g. asbestos workers, coal miners, beryllium miners, cement workers etc. 5. In an asthma attack, histamine is released from sensitized mast cells. The histamine causes airway constriction, accumulation of fluid and mucus, and inability to breathe. The Effects of High Altitude (page 173) 1. (a) Less oxygen is available for metabolic activity so people become breathless and often dizzy. Associated effects are headache, nausea, tiredness and coughing. (b) Altitude sickness or mountain sickness. 2. (a) Heart and breathing rates increase. (b) Increased breathing rate increases the rate at which new air is brought into the lungs (compensating for lower oxygen). Increased heart rate pumps blood more rapidly to tissues to improve oxygen delivery. 3. (a) Any two of: RBC concentration in the blood may increase, the blood may become thicker, over a Biozone International 2009 Photocopying Prohibited 29 long period of time, capillary networks increase in density (b) Increased RBCs and blood concentration increase the amount of oxygen that can be carried. Increased capillary density increases the amount and efficiency of oxygen delivery to tissues. 2. See diagram. CS PS Pyloric sphincter between stomach and small intestine The Human Diet (page 177) Nutrients are required as (a) and (b) in any order: (a) An energy source (b) As the raw materials for metabolism, growth, and repair. 2. (a) The new food pyramid distinguishes between “healthy” and “unhealthy” fats, and “healthy” and “unhealthy” (refined) carbohydrate sources. This is contrary to the older pyramid, which placed all fats together as to be avoided, and recommended that all carbohydrates form the base of the food pyramid. The new pyramid recommends a high intake of plant oils which correlates with reduced rates of heart disease. (b) Evidence: Althoug...
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