(1) The auditory pathway is auricle → external auditory canal → 1 tympanic membrane →3 ossicles →6 cochlea → auditory nerve → auditory pathway in cerebral cortex. There are auditory receptors in the cochlea, which generate nerve impulses under the stimulation of vibration. (2) The formation process of vision is that the light reflected by external objects passes through the cornea and aqueous humor, enters the eyeball from the pupil, and then passes through the lens and the lens. It can form a clear image on the retina and stimulate the photoreceptor cells on the retina. The nerve impulses generated by these photoreceptor cells travel along the optic nerve to the visual center of the cerebral cortex, forming vision. As shown in the figure, there are respiratory center and cardiovascular movement center in the gray matter of brain stem 7. (3) In the human nervous system, eight cerebellums can maintain the balance of human body. Make the movements coordinated and accurate. 4. The semicircular canal can detect the direction of head movement, which also plays an important role in maintaining human balance. (4) The place where the cell bodies of neurons meet is gray, which is called gray matter, and the gray matter of the brain is on the surface. So it is also called cerebral cortex. Tissue is formed as a result of cell differentiation. So the answer is: (1) 1→3→6 6 Cochlea (2) Cornea → aqueous humor → lens → vitreous body → retina → optic nerve → visual center 7 brain stem (3)8 cerebellum 4 semicircular canal (4) Cell body differentiation.