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shock results from lack of fluid or blood volume.

A. Increasing fluid intake: Hypervolemia is characterized by excess extracellular fluid volume, often due to renal failure, heart failure, or excessive sodium retention. Increasing fluid intake would further expand intravascular and interstitial volume, worsening edema, hypertension, and risk of pulmonary congestion.

B. Administering intravenous fluids: Intravenous fluids are indicated in hypovolemia or shock states, not in fluid overload. Administering IV fluids in hypervolemia would exacerbate increased preload, elevate hydrostatic pressures, and potentially precipitate complications such as pulmonary edema or heart failure exacerbation.

C. Reversing the underlying cause of fluid retention: Management of hypervolemia targets the root cause, such as impaired renal excretion, excessive sodium intake, or heart failure. Interventions may include diuretics, sodium restriction, fluid restriction, or optimizing cardiac function, all directed at correcting the mechanism driving fluid accumulation.

D. Stimulating thirst mechanisms: Stimulating thirst would increase fluid intake and further worsen volume overload. In hypervolemia, strategies often involve fluid restriction rather than encouraging intake, as the primary issue is excess circulating volume, not deficiency.

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.