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Every time you take a breath, you are (1) _____ the respiratory surfaces of your lungs. Each lung has approximately 300 million tiny thin-walled outpouching air sacs called (2) ____.
Inhaled air dead-ends in these (2), each of which is surrounded by a network of pulmonary (3) _______ into which oxygen from air diffuses and is exchanged for (4) ___ ___ waste gases diffusing from the bloodstream into alveolar cavities.
The (5) ____ _____ surrounds each lung. In succession, air passes through the nasal cavities, pharynx, and (6) _____, past the epiglottis into the (7) ______ (the space between the true vocal cords), into the trachea, and then to the (8) _____, (9) _____, and alveolar ducts. Exchange of gases occurs across the epithelium of the (10)______.
In addition to gas exchange, breathing has other functions, such as ridding the body of excess heat and water vapor, adjusting the body's acid-base balance, and producing (11) ____ to communicate with other creatures.
A. pleural membrane
B. bronchioles
C. ventilating
D. vocalizations
E. alveoli
F. larynx
G. capillaries
H. glottis
I. bronchi
J. carbon dioxide

During inhalation, the (1) _____ moves downward and flattens, and the (2) ____ moves outward and upward. When these things happen, the chest cavity volume (3) _______ and the internal pressure (4)_____.
When the thoracic (chest) cavity expands during inhalation, the lungs must expand too because water molecules in the (5) _____ fluid are cohesive and behave like a "glue" binding the lungs to the thoracic wall. With active expiration (breathing out), the muscles in the abdominal wall contract, and pressure is exerted upward on the (6) _____, decreasing the volume of the chest cavity. The internal (7) _____ muscles also contract, pulling the chest wall downward and inward and further decreasing the volume of the chest cavity. Internal pressure (8) _____ and flows up the airways and outward because pressure in the alveoli is (9) _____ than the atmospheric pressure.
Quite exhalation is (10) _____; the muscles relax and the lungs recoil without any further energy outlays after an inhalation.
(11) _________ is the distension of lungs and the loss of gas exchange efficiency such that running, walking, and even exhaling are painful experiences. At least 90 percent of all (12) ____ ____ deaths are the result of cigarette smoking; only about 10 percent of afflicted individuals will survive.
A. increases
B. drops
C. greater
D. passive
E. intercostal
F. diaphragm
G. rib cage
H. intrapleural
I. lung cancer
J. Emphysema

Solution Preview

First question:
1. c (ventilating)
2. e (alveoli)
3. g (capillaries)
4. j (carbon dioxide)
5. a (pleural ...