Medical CategoriesAccidents, Emergencies And Poisons
Diseases Of The Blood And Ductless Galnds
Diseases Of The Eye And Ear
Diseases Of The Nervous System
Diseases Of The Skin
Diseases Of Women
Intoxicants And Sun Strokes
Kidney And Bladder
Medical Uses Of Some Common Household Articles
Obstetrics Or Midwifery
Patent Medicines And Secret Forumla
Category: Diseases of The Nervous System
Taste-Buds. There are three kinds of papillae or eminences on the
human tongue,--the circumvallate, the fungiform and the filiform. The
circumvallate are from seven to twelve in number and lie near the root of
the tongue, arranged in the form of a V, with its open angle turned
forward. Each one is an elevation of the mucous membrane, covered by
epithelium and surrounded by a trench. On the sides of the papillae,
embedded in the epithelium, are small oval bodies called taste-buds. These
taste-buds consist of a sheath of flattened, fusiform cells, enclosing a
number of spindle-like cells whose tapering ends are prolonged into a
hair-like process. As the filaments of the gustatory nerves terminate
between these rod-like cells, it is probable that they are the true
sensory cells of taste.
In the human tongue taste-buds are also found in the fungiform papillae,
often seem as red dots scattered over its surface; and to an area just in
front of the anterior pillar of the fauces. It is also possible that
single taste-cells are scattered over the tongue, as the sense of taste
exists where no taste-buds can be found.
Many so-called tastes are really smells. This is easily proved by
compressing the nostrils and attempting to distinguish by taste different
articles of food.
The taste sensation is greatest when the exciting substance is at the
temperature of the body. There is no perceptible sweetness to sugar when
the tongue has been dipped for a half-minute in water either at the
freezing temperature or warmed to 50 degrees C. Neither is there any sense
of taste until the substance is dissolved by the natural fluids of the
mouth, as will be seen by wiping the tongue dry and placing sugar upon it.
The four primary taste-sensations are bitter, sweet, sour and salt. These
probably have separate centers and nerve fibers. Sweet and sour tastes are
chiefly recognized at the front and bitter and alkaline tastes at the back
of the tongue. The same substance will often excite a different sensation,
according as it is placed at the front or back of the tongue.
There are also laws of contrast in taste sensations. Certain substances
will enhance the flavor of another and others will destroy it. Again,
certain tastes may disguise others without destroying them, as when an
acid is covered with a sweet.
Next: INSANITY. History
Previous: INFANTILE PARALYSIS. (Acute Anterior Polio Myelitis)