Final answer:
A fluid-filled cyst or a collection of nerve cells outside the brain and spinal cord is called a ganglion or cyst. The cerebrospinal fluid (CSF) is crucial for cushioning the brain and spinal cord, circulating nutrients, and removing waste.
Step-by-step explanation:
The term that means a fluid-filled cyst or a collection of nerve cells outside the brain and spinal cord is a ganglion when referring to the collection of nerve cells, or could be described as a cyst when referring specifically to a fluid-filled sac. The cerebrospinal fluid (CSF) plays a critical role within the central nervous system (CNS). CSF is a clear bodily fluid that circulates in the ventricular system of the brain and the central canal of the spinal cord, providing cushioning for the brain within the skull, circulates nutrients, and removes waste products. It is produced by ependymal cells in the choroid plexus filtering the blood.
The ventricular system is connected to the subarachnoid space by apertures, allowing CSF to flow and surround the CNS. This is significant for the protection and mechanistic operation of the brain and spinal cord. If the production or absorption of CSF is disrupted, it can lead to conditions like hydrocephalus, which causes an enlargement of the ventricles and puts pressure on the brain tissue.