Final answer:
The primary function of cerebrospinal fluid (CSF) is mechanical cushioning, acting as a shock absorber for the central nervous system and aiding in the removal of metabolic wastes.
Step-by-step explanation:
Primary Function of Cerebrospinal Fluid (CSF)
The primary function of cerebrospinal fluid (CSF) is mechanical cushioning. It acts as a shock absorber to protect the brain and spinal cord, which are parts of the central nervous system (CNS), from injury due to impact or sudden movements. The CSF also serves several other critical functions such as the distribution of neuroendocrine factors, removal of metabolic wastes, and prevention of brain ischemia by regulating intracranial pressure, which facilitates blood perfusion. Such regulatory roles are essential for maintaining a stable environment suitable for the CNS functions.
The CSF is produced in the choroid plexuses and circulates through the ventricles and subarachnoid space surrounding the brain and spinal cord. By being reabsorbed into the bloodstream via arachnoid granulations, the CSF also takes with it metabolic wastes from the nervous tissue. This system helps keep the brain adequately nourished, free from waste, and well protected by forming a fluid cushion within the dura mater, a tough protective membrane.
Given the options A) Nutrient transport, B) Protection against pathogens, C) Mechanical cushioning, and D) Temperature regulation, the answer is C) Mechanical cushioning, reflecting its role in protecting the brain and spinal cord by surrounding them in a cushioning fluid buffer.