What is the purpose of valves in veins?.
Prevent backflow of blood.
Aid in redirection of blood flow.
Keep oxygenated blood from mixing with unoxygenated blood.
Aid in the pumping of blood.
The Correct Answer is A
Veins have valves that ensure blood flows toward your heart. They work hard, against gravity, to bring the blood that flowed down via arteries back up to your heart. This prevents the backflow of blood.
Choice B rationale:
Veins do not aid in the redirection of blood flow. Their primary function is to return deoxygenated blood from the body back to the heart.
Choice C rationale:
The function of preventing oxygenated blood from mixing with unoxygenated blood is not performed by the valves in veins but by the structure of the circulatory system itself.
Choice D rationale:
While veins do aid in the circulation of blood, they do not aid in the pumping of blood. The pumping action is performed by the heart.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale:
Innate immunity is not an acquired immunity. Acquired immunity refers to immunity that develops after exposure to a specific pathogen.
Choice B rationale:
Innate immunity does not retain a memory of a pathogen after defeating it. This is a characteristic of adaptive immunity.
Choice C rationale:
Innate immunity does not offer protection against a particular pathogen. It provides a general defense against a wide range of invaders.
Choice D rationale:
Innate immunity is present at birth. It provides a fast response that involves first- and second-line defenses.
Correct Answer is C
Explanation
Choice A rationale:
While the nasopharynx does play a role in warming and moistening inspired air, this is not its primary function.
Choice B rationale:
The nasopharynx does not primarily filter dust. This function is mainly performed by the nasal cavity and the hairs within the nostrils.
Choice C rationale:
The nasopharynx provides openings for the right and left Eustachian tubes. These tubes connect the middle ear to the nasopharynx and help equalize air pressure on either side of the eardrum.
Choice D rationale:
The nasopharynx does not contain olfactory receptors responsible for the sense of smell. These receptors are located in the nasal cavity.
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