Which of the following factors would decrease the amount of oxygen discharged by hemoglobin to peripheral tissues?

Correct Answer: D

Rationale: The correct answer is D: decreased amounts of BPG. BPG binds to hemoglobin, reducing its affinity for oxygen. Without BPG, hemoglobin holds onto oxygen tightly, decreasing its release to tissues. Increased temperature (choice A) and decreased pH (choice B) actually enhance oxygen release by hemoglobin through the Bohr effect. Decreased tissue PO2 (choice C) triggers hemoglobin to release more oxygen due to the oxygen-hemoglobin dissociation curve.

Correct Answer: A

Rationale: The correct answer is A: apneustic. Stimulation of the apneustic center in the brainstem prolongs inspiration by sending signals to the respiratory muscles to maintain inspiration. The apneustic center plays a role in regulating the depth and duration of breathing. Explanation for why other choices are incorrect: B: Pneumotaxic center helps regulate the respiratory rate by inhibiting inspiration, not prolonging it. C: Expiratory center is responsible for controlling expiration, not inspiration. D: Baroreceptor center is involved in regulating blood pressure, not respiratory functions.

Correct Answer: C

Rationale: The correct answer is C: alveoli. The conducting zone of the respiratory system includes structures that transport air to and from the gas exchange sites. Alveoli are the primary sites of gas exchange, not part of the conducting zone. Pharynx (A), nasal cavity (B), and bronchi (D) are all part of the conducting zone as they help in air transportation but do not directly participate in gas exchange like alveoli do. Therefore, alveoli is the correct answer as it does not belong to the conducting zone.

Correct Answer: A

Rationale: The correct answer is A: cilia. Cilia are tiny hair-like structures in the respiratory tract that sweep mucus and dirt out of the lungs to keep them clean. Bronchioles are small airways in the lungs through which air passes, not involved in filtering. Hair in the lungs is not a natural structure; it would be harmful. Choice D is incorrect because not all options listed are involved in filtering and keeping the mucus and dirt away from the lungs.

Correct Answer: C

Rationale: The correct answer is C: emphysema. Smoking is a leading cause of emphysema due to the damage it causes to the air sacs in the lungs. This damage leads to decreased lung function, shortness of breath, and other respiratory problems. Hypoxia (choice A) is a condition of low oxygen levels in tissues, not directly caused by smoking. Cancer (choice B) is also linked to smoking, but emphysema is specifically associated with lung damage. Macrosis (choice D) is not a recognized medical condition related to smoking or any other factor.