A) Myelin sheaths form an insulating layer around the axons of neurons in the central and peripheral nervous systems. These structures function to slow the transmission of impulses along the axon.
B) Myelin sheaths form an insulating layer around the axons of neurons in the central and peripheral nervous systems. These structures function to speed up the transmission of impulses along the axon.
C) Myelin sheaths form an insulating layer around the axons of neurons only in the peripheral nervous system. These structures function to speed up the transmission of impulses along the axon.
D) Myelin sheaths form an insulating layer around the cell bodies of neurons in the central and peripheral nervous systems. These structures function to speed up the transmission of impulses along the axon.

A) Bipolar
B) Multipolar
C) Unipolar
D) Anaxonic

A) The gray matter of the cerebellum is referred to as the arbor vitae or the "tree of life."
B) The white matter of the cerebrum consists of neuron cell bodies, dendrites, unmyelinated axons and neuroglia. Myelinated axons and neuroglia can be found in the gray matter.
C) The white matter of the spinal cord has a characteristic butterfly shape.
D) The gray matter of the cerebrum consists of neuron cell bodies, dendrites, unmyelinated axons and neuroglia. Myelinated axons and neuroglia appear white and are insulated.