Final answer:
The Valsalva maneuver demonstrates the increase of intra-abdominal pressure to aid in defecation, urination, and childbirth by contracting the diaphragm and abdominal muscles while closing the glottis.
Step-by-step explanation:
The Valsalva maneuver would be utilized to demonstrate how increasing intra-abdominal pressure can aid in bodily functions such as defecation, urination, and childbirth. When performing the Valsalva maneuver, an individual voluntarily contracts their diaphragm and abdominal wall muscles while closing their glottis. This action stabilizes the volume and pressure of the peritoneal cavity, ultimately increasing the pressure on the intestinal tract during defecation, urinary tract during urination, or the reproductive tract during childbirth.