Both mean systemic pressure and venous return (or, vascular function) curve are affected by changes in blood volume or venous tone:
1. Increased blood volume or venous tone (e.g., sympathetic activity) increase mean systemic pressure and venous return curve switches to the right. A new intersection point is reached, where both cardiac output and right atrial (RA) pressure are increased. (choice B)
2. Decreased blood volume (e.g., acute hemorrhage) or venous tone (e.g., spinal anesthesia) produce the opposite effect—decreased mean systemic pressure and venous return curve switches to the left. A new intersection point is reached, where both cardiac output and right atrial (RA) pressure are decreased. (choice
1. Increased blood volume or venous tone (e.g., sympathetic activity) increase mean systemic pressure and venous return curve switches to the right. A new intersection point is reached, where both cardiac output and right atrial (RA) pressure are increased. (choice B)
2. Decreased blood volume (e.g., acute hemorrhage) or venous tone (e.g., spinal anesthesia) produce the opposite effect—decreased mean systemic pressure and venous return curve switches to the left. A new intersection point is reached, where both cardiac output and right atrial (RA) pressure are decreased. (choice