ANATOMY AND PHYSIOLOGY OF THE SENSORY SYSTEM
Section I. GENERAL
The ability to sense stimuli is vital to man's survival. If pain could not be sensed,
burns would be common. Internal problems such as an inflamed appendix or a
stomach ulcer could be unnoticed without pain. Without sight there is a greater risk of
injury from obstacles. Harmful gas could be inhaled if there were no sense of smell.
Loss of a sense of hearing would keep us from recognizing hazards such as automobile
horns. And if there were no taste, toxic substances could be ingested. If we could not
"sense" out environment and make the necessary adjustments, we probably could not
survive on our own.
In this subcourse, you will see the letters EENT and HEENT. EENT stands
for eyes, ears, nose, and throat. HEENT stands for head, eyes, ears, nose,
THE SENSORY PATHWAYS
a. Sensations. The body is continuously bombarded by types of information
called stimuli (stimulus, singular). Those few stimuli which are consciously perceived (in
the cerebral hemispheres) are called sensations. Structures that detect changes in
man's external and internal environment produce sensations on the senses.
b. Senses and Receptions. The senses and the location of their receptors are
Vision--receptors in the eyes.
Smell--receptors in the nose.
Hearing--receptors in the ears.
Taste--receptors in the tongue.
Touch, heat, cold, pain --receptors in the skin.
Position--receptors in the muscles, joints, inner ear.
Hunger, thirst--receptors in the tongue, pharynx, mouth.