Dynamic equilibrium also known as Homeostasis is responsible for these fluctuations. Hope it helped!
Cerebrospinal Fluid
Produced by the choroid plexuses of the brain, the cerebral spinal fluid is contained in the subarachnoid cavity and spinal canal. It is reabsorbed by the arachnoid granulations.
Besides acting as a cushion for the CNS, the cerebral spinal fluid plays a critical part in the immunology of the central nervous system, blood flow in the CNS and autoregulation.
Answer:The excretory system is a close partner with both the circulatory and endocrine system. The circulatory system connection is obvious. Blood that circulates through the body passes through one of the two kidneys. Urea, uric acid, and water are removed from the blood and most of the water is put back into the system.
Explanation:
It's a pyramid of numbers, I believe.