Final answer:
Protoplasmic astrocytes are primarily found in the gray matter of the CNS, while fibrous astrocytes are mainly located in the white matter. Both types of astrocytes play vital roles in supporting neuronal function, maintaining homeostasis, and forming the blood-brain barrier.
Step-by-step explanation:
Astrocytes are a type of glial cell found within the central nervous system (CNS). There are two major types of astrocytes: protoplasmic and fibrous. Protoplasmic astrocytes are located predominantly in the gray matter of the brain and spinal cord, where they are involved in supporting neuronal function, regulating neurotransmitter levels, and maintaining the blood-brain barrier.
Meanwhile, fibrous astrocytes are primarily found in the white matter and are characterized by their long unbranched processes. They contribute significantly to the physical support of the CNS and help maintain the proper ion balance for the conduction of nerve impulses along axons.
Astrocytes in general perform various crucial functions such as repairing brain injury, modulating neuronal activity, and securing materials from the blood — a process which can be visualized by brain imaging techniques like PET and fMRI. They also participate in the formation and function of the synapses, the sites of communication between neurons.