Mrs. M has suffered for many years from ulcerative colitis, a disease in which ulcers and scar tissue form in the lining of the intestine, usually affecting the ileum and/or colon. About a half-hour after eating a large meal, she became acutely ill with a distended abdomen and low blood pressure and finally collapsed. She was brought into the emergency room and diagnosed with a bowel obstruction caused by scar tissue blocking her large intestine. The ER doctor said this obstruction caused a decrease in her blood volume. How could an obstructed bowel make blood volume decrease