Venoconstriction increases which of the following?

• A. Heart rate
• B. Respiratory rate
• C. Venous return to the heart
• D. Arterial blood pressure

Answer: (C)

Verified step by step guidance

1. Understand the concept of venoconstriction: Venoconstriction refers to the narrowing of the veins, which is caused by the contraction of smooth muscle cells in the vessel walls. This process reduces the diameter of the veins and increases the pressure within them.
2. Consider the effect of venoconstriction on blood flow: When veins constrict, they push more blood back towards the heart. This is because the reduced diameter increases the pressure, which helps propel blood through the venous system.
3. Relate venoconstriction to venous return: Venous return is the flow of blood back to the heart. Venoconstriction increases venous return because the constricted veins push more blood towards the heart, enhancing the volume of blood returning to the heart.
4. Analyze the impact on arterial blood pressure: Increased venous return can lead to an increase in cardiac output, which may subsequently raise arterial blood pressure. However, the direct effect of venoconstriction is primarily on venous return rather than arterial blood pressure.
5. Conclude the primary effect: The main physiological effect of venoconstriction is the increase in venous return to the heart, as it directly influences the amount of blood being returned to the heart for circulation.