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 A
Explanation
Choice A rationale:
Arteries carry oxygen-rich blood away from the heart to various organs and tissues.
Choice B rationale:
Arteries do not carry blood away from the body. They transport blood within the body.
Choice C rationale:
While arteries do distribute blood throughout the body, this statement is too general and does not accurately describe the primary function of arteries.
Choice D rationale:
Arteries do not carry blood to the heart; this is the function of veins.
Correct Answer is C
Explanation
The correct answer is: c. Air flows into the lungs.
Choice A: A pneumothorax forms, collapsing the lungs.
A pneumothorax occurs when air enters the pleural space, the area between the lung and the chest wall, causing the lung to collapse. This condition is typically caused by trauma or a spontaneous rupture of a lung bleb, not by a drop in lung pressure below atmospheric pressure. When the pressure in the lungs drops below atmospheric pressure, it facilitates the inflow of air into the lungs, not the collapse of the lungs.
Choice B: The bronchioles constrict, causing respiratory distress.
Bronchiolar constriction, or bronchoconstriction, is a narrowing of the airways in the lungs due to the tightening of surrounding smooth muscle. This can cause respiratory distress and is commonly seen in conditions like asthma. However, this is not directly related to the pressure changes in the lungs relative to atmospheric pressure. The primary effect of a drop in lung pressure below atmospheric pressure is the inflow of air, not bronchoconstriction.
Choice C: Air flows into the lungs.
When the pressure in the lungs drops below atmospheric pressure, a pressure gradient is created that allows air to flow into the lungs. This process is known as inspiration or inhalation. The diaphragm and intercostal muscles contract to increase the volume of the thoracic cavity, thereby decreasing the pressure within the lungs relative to the outside atmosphere, causing air to rush in.
Choice D: Air flows out of the lungs.
Air flows out of the lungs, or expiration, occurs when the pressure inside the lungs exceeds atmospheric pressure. This happens when the diaphragm and intercostal muscles relax, decreasing the volume of the thoracic cavity and increasing the pressure within the lungs. This is the opposite of what happens when lung pressure drops below atmospheric pressure.
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