Does venous return increase or decrease during inspiration?

During inspiration, venous return increases due to several physiological mechanisms. As the diaphragm contracts and moves downward, it creates a negative pressure in the thoracic cavity. This negative pressure facilitates the movement of blood from the veins into the thoracic cavity, effectively pulling the blood from the central veins towards the heart.

Additionally, the increased intrathoracic pressure during inspiration reduces thoracic vascular resistance, enabling more blood to flow back to the heart. The increase in venous return is also aided by abdominal pressure as the diaphragm descends, leading to a relative increase in the pressure gradient that encourages blood flow from the peripheral veins towards the heart.

Overall, the combination of decreased thoracic pressure and increased abdominal pressure during inspiration maximizes venous return, making the correct answer to the question that it increases.