Veins are referred to as capacitance vessels because they:
Contract forcefully to move blood.
Have the ability to generate high blood pressure
Store a large volume of blood at low pressure
Contain one-way valves to prevent backflow.
The Correct Answer is C
A. Contract forcefully to move blood: Veins do not generate strong contractile force like arteries. Their walls contain less smooth muscle and elastin, making them less capable of producing active propulsion of blood. Venous return primarily depends on skeletal muscle contraction, respiratory pressure changes, and pressure gradients rather than forceful venous contraction.
B. Have the ability to generate high blood pressure: High pressure is characteristic of the arterial system, particularly large elastic arteries near the heart. Veins operate under low-pressure conditions and are structurally designed to accommodate volume rather than generate or withstand high pressures.
C. Store a large volume of blood at low pressure: Veins are termed capacitance vessels because they are highly compliant and can hold approximately 60–70% of the total blood volume at any given time. Their thin walls and large lumens allow them to expand and serve as a blood reservoir, which can be mobilized during sympathetic stimulation.
D. Contain one-way valves to prevent backflow: While many veins, especially in the extremities, contain valves that prevent retrograde flow, this feature does not define them as capacitance vessels. The term “capacitance” specifically refers to their ability to store and accommodate large volumes of blood at low pressure.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is {"dropdown-group-1":"A"}
Explanation
A. Vascular tone: All blood vessels containing smooth muscle maintain a baseline level of partial contraction known as vascular tone. This resting state of constriction is regulated by autonomic input and local factors, allowing vessels to rapidly dilate or constrict as needed to regulate blood pressure and tissue perfusion.
B. Vasodilation: Vasodilation refers to an active widening of blood vessels beyond their baseline tone. It is a dynamic adjustment rather than a constant state, and not all vessels are continuously dilated under normal physiologic conditions.
C. Vasoconstriction: Vasoconstriction is also an active process in which vascular smooth muscle contracts further than baseline tone. It occurs in response to sympathetic stimulation or hormonal signals, but it is not the constant resting condition of all vessels.
D. Blood pressure: Blood pressure refers to the force exerted by circulating blood on vessel walls, not a property that vessels inherently “exhibit.” While vessels are exposed to blood pressure, the question relates to their intrinsic smooth muscle activity, which is vascular tone.
Correct Answer is C
Explanation
A. To supply blood to the kidneys: The kidneys are primarily supplied by the renal arteries, which branch directly from the abdominal aorta inferior to the origin of the celiac trunk. The celiac trunk does not provide arterial blood flow to renal structures.
B. To carry deoxygenated blood to the inferior vena cava: The celiac trunk is an arterial vessel arising from the abdominal aorta. It carries oxygenated blood away from the heart, not deoxygenated blood toward the inferior vena cava, which is a venous structure.
C. To supply blood to the liver, stomach, and spleen: The celiac trunk is a major unpaired branch of the abdominal aorta that trifurcates into the left gastric, splenic, and common hepatic arteries. These branches supply oxygenated blood to foregut structures including the liver, stomach, spleen, and portions of the pancreas and duodenum.
D. To transport blood to the lower limbs: Blood supply to the lower limbs is provided by the common iliac arteries, which arise from the distal abdominal aorta. The celiac trunk functions much higher in the abdominal cavity and does not contribute to lower extremity circulation.
E. To drain blood from the digestive organs: Venous drainage from the digestive organs occurs through the hepatic portal vein and associated venous system, not the celiac trunk. The celiac trunk is part of the arterial supply, not venous return.
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