A gym teacher was trying out a yoga class. Several stretches required her to twist her abdomen into unfamiliar positions. What allowed her abdominal organs to slide past each other without causing injury?

The serous membrane lining the abdominal cavity and covering many of its organs produces fluid that reduces friction. This lets the organs slide past one another as the teacher twists, helping prevent injury. The meninges surround the brain and spinal cord, vertebrae form the backbone, and blood in the spleen does not provide this protective lubrication.

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