All of the following factors normally increase the length of the ventricular cardiac muscle fibers except:: (A) Increased venous tone., (B) Increased total blood volume, (C) Increased negative intrathoracic pressure., (D) Lying-to-standing change in posture
Answer is D. D i.e. Lying to standing change in posture When a person moves from a supine position to standing position volume of blood pools in the lower extremity because of high compliance of veins & venous return decreases. As a result of decreased venous return the length of ventricular cardiac muscle fibres is decreasedQ and so the cardiac output in accordance with frank-sterling law.