Final answer:
The skeletal muscle pump greatly affects the return of venous blood and lymph to the heart by increasing venous pressure when skeletal muscles contract, encouraging upward blood flow thanks to one-way valves, and assisting with lymph movement.
Step-by-step explanation:
The skeletal muscle pump has a significant impact on the return of venous blood and lymph to the heart. This mechanism aids in the movement of blood against the force of gravity and assists veins that have lower pressure compared to arteries.
When skeletal muscles contract, particularly during activities such as walking or running, they press on nearby veins. This pressure leads to blood being pushed upwards thanks to one-way valves within the veins that prevent backflow, allowing for an effective return of blood to the heart.
Furthermore, the contractions of the muscles around lymph vessels help move lymph through the lymphatic system until it ultimately returns to the bloodstream via the larger veins in the chest.
The role of the skeletal muscle pump is paramount because it directly augments blood velocity when moving from venules to veins and increases venous return.
Without the action of the skeletal muscle pump, there is a risk of blood pooling in lower extremities, potentially leading to a lack of sufficient oxygenated blood reaching the brain, causing syncope.
This mechanism is crucial in maintaining an efficient return of systemic blood and lymph to the heart and is particularly active during physical activity.