The venous reserve is the blood held in venous networks within which structures?

1. Roughly 21 percent of venous blood sits in networks inside the liver, the bone marrow and the integument. 2. That parked volume is named the venous reserve. 3. Sympathetic venoconstriction stiffens those walls and pushes the reserve back toward the heart for redistribution. 4. The other organ groups listed are perfused targets rather than named reservoirs of venous blood. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 20 "The Cardiovascular System: Blood Vessels and Circulation", section 20.1 Structure and Function of Blood Vessels_