THE SPECIAL SENSES
Section I. INTRODUCTION
GENERAL VERSUS SPECIAL SENSES
a. The human body is continuously bombarded by all kinds of stimuli. Certain
of these stimuli are received by sense organs distributed throughout the entire body.
These are referred to as the general senses.
b. Certain other stimuli (table 13-1) are received by pairs of receptor organs
located in the head. These are the special senses.
bulbus oculi (eye)
ear (membranous labyrinth)
olfactory hair cells in nose
taste buds in mouth
Table 13-1. The special senses.
c. Since the general senses respond to immediate contact, they are very
short range. In contrast, the special senses are long range.
INPUT TO BRAIN
From the special sense organs, information is sent to the brain through specific
cranial nerves. When this information reaches specific areas of the cerebral cortex, the
sensations are perceived at the conscious level.
Section II. THE SPECIAL SENSE OF VISION
Within the bulbus oculi (eyeball) is an inner layer called the retina. See Figure
13-1 for the location of the retina within the bulbus oculi. See Figure 13-2 for the types
of cells found within the retina.