which one of the following statements is false about the trachea?

Correct Answer: B

Rationale: The correct answer is B because the trachea is not covered by the epiglottis; it is a flap of cartilage that covers the larynx during swallowing, not the trachea. A is correct as the trachea is supported by C-shaped rings of cartilage. C is correct as the trachea branches into the right and left bronchi. D is incorrect as B is false about the trachea.

Correct Answer: B

Rationale: Carbonic anhydrase is crucial for acid-base balance by catalyzing the interconversion of carbon dioxide and bicarbonate ions in the blood. The kidneys regulate blood pH by reabsorbing bicarbonate and excreting hydrogen ions. Therefore, carbonic anhydrase in the kidneys plays a vital role in maintaining acid-base balance. The liver is not directly involved in this process but helps in detoxification and metabolism. The heart and pancreas do not have a primary role in acid-base balance regulation. Thus, the correct answer is B: Kidneys.

Correct Answer: A

Rationale: The correct answer is A: LDL 150 mg/dL. LDL cholesterol is known as "bad" cholesterol, and high levels are a risk factor for atherosclerosis. LDL can build up in the arteries, leading to plaque formation and narrowing of blood vessels. Elevated LDL levels increase the risk of cardiovascular disease. Summary: B: Triglycerides 140 mg/dL - Elevated triglycerides are a risk factor for heart disease, but not as directly linked to atherosclerosis as LDL. C: Cholesterol 190 mg/dL - Total cholesterol includes both HDL and LDL, so this value alone does not specify the risk factor for atherosclerosis. D: HDL 100mg/dL - High levels of HDL are actually considered beneficial as it is known as "good" cholesterol and helps to remove LDL from the bloodstream, reducing the risk of atherosclerosis.

Correct Answer: D

Rationale: The correct answer is D because elastic fibers are more abundant in the bronchi and bronchioles than the upper respiratory tract. Elastic fibers provide elasticity and recoil to help with airway expansion and contraction during breathing. This is crucial in the bronchi and bronchioles to maintain airflow dynamics. Choice A is incorrect because regular bronchioles do not contain glands; they are found in the respiratory bronchioles. Choice B is incorrect because larynx contains a significant amount of cartilage, not smooth muscle. Choice C is incorrect because goblet cells are abundant in the larger bronchi, trachea, and bronchioles, not in the small bronchi and respiratory bronchioles.

Correct Answer: D

Rationale: The correct answer is D: Peripheral chemoreceptors respond to decreases in arterial pO2. These chemoreceptors located in the carotid bodies and aortic bodies detect changes in arterial pO2 levels, triggering an increase in ventilation to compensate for low oxygen levels. The apneustic center (A) is located in the pons, not the medulla. Central chemoreceptors (B) primarily respond to changes in arterial CO2 levels, not oxygen concentrations. The chemoreceptors in the aortic bodies (C) primarily respond to changes in arterial pCO2, not pH. Overall, choice D is correct due to the specific role of peripheral chemoreceptors in detecting decreases in arterial pO2 levels and regulating ventilation accordingly.