Discuss the determinants of venous return to the heart.
The factors that influence VR are captured in 2 formulae; VR = CO, and VR = (MSFP-RAP) / Venous Resistance. Candidates that used these as the backbone structure of their answer scored well. Quite a few candidates failed to consider factors that affect left heart CO also effect VR. Recognising that CO does = VR appeared to elude some candidates.
For a diagram, the exam candidate would probably have to reproduce something like this:
Beard, Daniel A., and Eric O. Feigl. "Understanding Guyton's venous return curves." American Journal of Physiology-Heart and Circulatory Physiology 301.3 (2011): H629-H633.
Guyton, Arthur C. "Regulation of cardiac output." Anesthesiology: The Journal of the American Society of Anesthesiologists 29.2 (1968): 314-326.
Guyton, A. "Circulatory Physiological: Cardiac Output and Its Regulation." Philadelphia and London: WB Saunders Company (1963).
Guyton, Arthur C. "Determination of cardiac output by equating venous return curves with cardiac response curves." Physiological reviews 35.1 (1955): 123-129.
Levy, MATTHEW N. "The cardiac and vascular factors that determine systemic blood flow." Circulation research 44.6 (1979): 739-747.
Guyton, Arthur C., Arthur W. Lindsey, and Berwind N. Kaufmann. "Effect of mean circulatory filling pressure and other peripheral circulatory factors on cardiac output." American Journal of Physiology-Legacy Content 180.3 (1955): 463-468.
Guyton, Arthur C., James H. Satterfield, and Jeff W. Harris. "Dynamics of central venous resistance with observations on static blood pressure." American Journal of Physiology-Legacy Content 169.3 (1952): 691-699.
Guyton, Arthur C., Dimitri Polizo, and George G. Armstrong. "Mean circulatory filling pressure measured immediately after cessation of heart pumping." American Journal of Physiology-Legacy Content 179.2 (1954): 261-267.
Guyton, Arthur C., et al. "Venous return at various right atrial pressures and the normal venous return curve." American Journal of Physiology-Legacy Content 189.3 (1957): 609-615.
Bendjelid, Karim. "Right atrial pressure: determinant or result of change in venous return?." Chest 128.5 (2005): 3639-3640.
Bendjelid, Karim. "Right atrial pressure: determinant or result of change in venous return?." Chest 128.5 (2005): 3639-3640.
Bressack, Michael A., and Thomas A. Raffin. "Importance of venous return, venous resistance, and mean circulatory pressure in the physiology and management of shock." Chest 92.5 (1987): 906-912.