What produces the movement labeled '2'?

Correct Answer: C

Rationale: Step 1: The movement labeled '2' is inhalation. Step 2: During inhalation, the diaphragm contracts and moves downward. Step 3: This creates more space in the thoracic cavity, allowing the lungs to expand and fill with air. Step 4: Therefore, the correct answer is C: diaphragm contracts produces the movement labeled '2'. Summary: Choice A and B are incorrect because the rectus abdominis is not directly involved in inhalation. Choice D is incorrect because the diaphragm needs to contract to create the necessary space for inhalation.

Correct Answer: C

Rationale: The correct answer is C because the Dorsal Respiratory Group (DRG) is involved in both inspiration and expiration, not just forced breathing. During quiet breathing, the DRG primarily controls inspiration, while the Ventral Respiratory Group (VRG) primarily controls expiration. In forced breathing, both the DRG and VRG are activated to increase respiratory effort. Choice A and B are both true statements as the DRG controls inspiration and the VRG controls expiration. Choice D is incorrect as the VRG is involved in both quiet and forced breathing, not just forced breathing.

Correct Answer: A

Rationale: The correct answer is A: visceral and parietal pleurae. The visceral pleura covers the surface of the lungs, while the parietal pleura lines the thoracic cavity. They form a double-layered membrane that helps reduce friction during breathing. Choices B and C are incorrect because the mediastinum is a central compartment in the thoracic cavity, not a layer of the pleura. Choice D is incorrect as it does not provide a valid alternative.

Correct Answer: A

Rationale: The correct answer is A: 500 million alveoli. The adult lung consists of approximately 300 million alveoli at birth, with an additional 200 million alveoli developing postnatally. This total of 500 million alveoli maximizes the surface area for efficient gas exchange in the lungs. Therefore, choice A is correct. Choices B, C, and D are incorrect because they do not accurately represent the estimated number of alveoli in the adult lung based on scientific research and anatomical studies.

Correct Answer: D

Rationale: The correct answer is D because the formation of the Adam's apple is influenced by the production of sex hormones, which increases during puberty, leading to growth in the laryngeal prominence. This growth is more prominent in males due to higher levels of testosterone. Therefore, all the factors mentioned in choices A, B, and C contribute to the formation of the Adam's apple.