Describe the factors that assist the return of systemic venous blood to the heart.
The factors that assist the return of the systemic venous blood to the heart are the contraction of skeletal muscles in the lower limbs and the pressure changes in the thorax and abdomen during respiration. Also, the presence of valves in the veins allows both of these pumps to contribute to the venous return. During the contraction of the skeletal muscles, the muscles would tighten around the vein passing through them, which increases the venous blood pressure, and the proximal valve opens-this pressure drives the blood toward the heart: action called milking. When the muscles relax, this valve closes and prevents the back-flow of blood away from the heart. As of the respiratory pump, when breathing in (inspiration), the diaphragm moves inferiorly-this causes a decrease in pressure in the thoracic cavity and an increase in pressure in the abdominal cavity; resulting in a greater volume of blood moving from the compressed abdominal veins into the decompressed thoracic veins. When the pressures reverse during expiration (breathing out), the valves in the veins prevent back-flow.
What is meant by a circulatory route? Define systemic circulation.
A circulatory route is a route in which blood flows. Systemic circulation includes all the arteries and arterioles that carry oxygenated blood from the left ventricle to systemic capillaries plus the veins and venules that carry deoxygenated blood returning to the right atrium after flowing through body organs.
Trace a drop of blood from the arch of the aorta through its systemic circulatory route to the tip of the big toe on your left foot and back to the heart again. Be sure to also indication which veins return the blood to the heart. .
The drop of blood's journey to the left big toe starts from the aorta. Flowing down the thoracic/ abdominal aorta, the blood drop next makes its way down the left femoral; then, the left femoral becomes the left popliteal.
