A) nucleolus.
B) cerebral cortex.
C) suprachiasmatic nuclei.
D) substantia nigra.
E) brainstem.

A) muscle and nerve cell function.
B) connective tissue function.
C) signal transduction and neurotransmission.
D) cellular adhesion and blood clotting.
E) none of the above.

A) certain brain cells have many extra orexin/hypocretin receptors, so that the cell receives too many messages to sleep.
B) the orexin/hypocretin receptor is missing, abnormal in structure, or unable to move to the surface of certain brain cells, blocking signals to stay awake.
C) a gene is missing in chromosome 6 that encodes the protein narcoleptin.
D) a viral infection activates genes that promote sleep.
E) four key genes are overexpressed.