During a normal inspiration, which event occurs first?
A. air flows into lungs
B. alveolar pressure becomes subatmospheric
C. diaphragm contracts
D. intrapleural pressure becomes more negative
E. thoracic volume increases
Answer: C. diaphragm contracts
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Chewed food mixed with saliva is called a ________, which is swallowed once mastication is complete.
Fill in the blank(s) with the appropriate word(s).
Active sites become exposed when calcium ions bind to
A) tropomyosin. B) actin. C) myosin. D) troponin. E) calcium channels.
Which of the following effects of aging is most vital to a person living in a hot, humid climate?
A) a decrease in melanocyte activity B) thinning of the epidermis of the skin C) a decrease in the number of Langerhans' cells D) a decrease in glandular activity E) All of the answers are correct.
Given the following list of organic molecules, which includes hormones? 1) Nucleic acid derivatives 2) Polypeptides 3) Steroids 4) Proteins
A. 1, 2, 3, 4 B. 1, 2, 3 C. 1, 3, 4 D. 1, 2, 4 E. 2, 3, 4