What is the proper sequence in the flow of air in humans?

Correct Answer: C

Rationale: The correct sequence is C: nasal cavities, pharynx, larynx, trachea, bronchi. Air enters through the nasal cavities, passes through the pharynx, then the larynx where the vocal cords are located, then enters the trachea, and finally branches into the bronchi leading to the lungs. This sequence follows the anatomical pathway of the respiratory system, ensuring proper filtration, warming, and humidification of the air. Choices A, B, and D have incorrect sequences that do not follow the anatomical order of the respiratory pathway, leading to an inaccurate flow of air in humans.

Correct Answer: D

Rationale: The correct answer is D because in the lungs, during gas exchange, carbon dioxide (CO2) is removed from the blood and exhaled. This leads to a lower PCO2 in the alveoli compared to the capillaries. The concentration gradient drives the diffusion of CO2 from the capillaries to the alveoli. Options A and B are incorrect because the partial pressure of CO2 (PCO2) and oxygen (PO2) differ between the alveoli and capillaries due to gas exchange. Option C is also incorrect as PCO2 is lower in the alveoli to facilitate the removal of CO2 from the blood.

Correct Answer: A

Rationale: Correct Answer: A - Increase in volume of thoracic cavity and fall in lung pressure Rationale: 1. During inspiration, the diaphragm contracts and moves downward, increasing the volume of the thoracic cavity. 2. The external intercostal muscles also contract, lifting the ribcage and further expanding the thoracic cavity. 3. As thoracic cavity volume increases, lung pressure decreases, creating a pressure gradient that allows air to flow into the lungs. Summary: B: Fall in pressure inside the lungs - This is a consequence of the increase in thoracic cavity volume, not the cause of air entering the lungs. C: Increased volume of thoracic cavity - This is correct but does not explain how air enters the lungs. D: Muscular expansion of lungs - Lungs do not expand on their own; it is the thoracic cavity that expands to create the pressure gradient for air entry.

Correct Answer: A

Rationale: The correct answer is A: Medulla (pons). The medulla, located in the brainstem, controls involuntary functions like breathing. Specifically, the medulla contains the respiratory center, which regulates breathing rhythm and depth. During forced breathing, the medulla sends impulses to the voluntary muscles involved in breathing, such as the diaphragm and intercostal muscles. The pons, which is closely connected to the medulla, assists in regulating breathing patterns. The vagus nerve (B) is responsible for parasympathetic functions, not voluntary breathing. The cerebral hemispheres (C) are primarily involved in higher brain functions, not breathing regulation. The spinal cord (D) plays a role in transmitting signals between the brain and muscles but does not initiate voluntary breathing impulses.

Correct Answer: B

Rationale: The correct answer is B: Ensure that informed consent is on the chart. This is the priority action because obtaining informed consent is essential before any procedure to ensure that the client understands the risks, benefits, and alternatives. Administering anxiolytic medication (A) may be necessary but is not the priority. Reinforcing teaching (C) and starting antibiotics (D) are important but not as urgent as ensuring informed consent.