Tongue – Mechanism of Stimulation

Tongue

In man the taste buds are found only in the mouth and are abundant in the
tongue. They are distributed over the dorsal and under surface of of the tongue,
on the laryngeal surface of the epiglottis, pharynx and on the cheek.

Each taste bud occupies the entire thickness of the epithelium. There is
an opening on its free surface known as the pore canal. Taste buds are
numerous at birth and their number decreases with age.

Taste sensation and disribution of taste cells

There are four primary or fundamental tastes. They are sweet, sour, salt
and bitter. Alkaline and metallic taste are also sometimes included.

Taste buds mediating the four primary taste are localized in certain
regions on the tongue. The taste bud sensitive to bitter taste are at the back of
the tongue. Those for sour tastes are on the lateral surface. Those mediating salt
at the anterior part of the dorsum near the tip. The taste bud sensitive to sweet
are near the tip.

The taste bud in the palate respond to sour and bitter taste but
have some sensitivity to sweet and salt. The pharynx and epiglottis are not
sensitive to all four tastes. It is found that both sweet and salt are insensitive to
taste in these regions.

Mechanism of Stimulation

Taste receptors are stimulated by substances in solution. The
dissolved substances act on the microvilli of the taste receptors which project
at the gustatory pore and sets up a generator potential to the receptor.

This inturn activates the afferent nerve ending at the base of the receptor, producing a propagated action potential in the nerve. The mechanism of
production of generator potential varies in different receptors of taste.

Tongue – Mechanism of Stimulation

Tongue

Mechanism of Stimulation

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