Physiology of Taste (Gustation)

This set of vocabulary flashcards covers the physiological mechanisms, anatomical structures, pathways, and clinical abnormalities related to the sense of taste (gustation).

Gustation

The physiology of taste, which involves specialized chemoreceptors that distinguish between nutritious substances and toxins.

Sweet

The primary taste modality triggered by sugars, alcohols, and some amino acids.

Salty

The primary taste modality triggered by metal ions (inorganic salts).

Sour

The primary taste modality triggered by hydrogen ions (acids).

Umami (Savory)

The primary taste modality triggered specifically by glutamate.

Bitter

The primary taste modality triggered by alkaloids such as quinine, caffeine, and nicotine; it has the lowest threshold as a protective mechanism.

Taste Buds

Sensory organs for taste found in the papillae, soft palate, tonsillar pillars, and epiglottis; they tend to degenerate with age.

Facial Nerve (CN VII)

The cranial nerve responsible for carrying taste sensation from the anterior $\frac{2}{3}$ of the tongue.

Glossopharyngeal Nerve (CN IX)

The cranial nerve responsible for carrying taste sensation from the posterior $\frac{1}{3}$ of the tongue.

Vagus Nerve (CN X)

The cranial nerve responsible for carrying taste sensation from the epiglottis, pharynx, and esophagus.

Gustatory Hairs

Microvilli of gustatory cells that contact dissolved chemicals in saliva to trigger receptor stimulation.

Nuclei of the Solitary Tract (NST)

The location in the medulla where second-order neurons of the taste pathway are situated.

Ventral Posteromedial (VPM) Nucleus

The part of the thalamus where third-order neurons of the taste pathway are located before projecting to the gustatory cortex.

Gustatory Cortex

The region in the parietal lobes where conscious perception of taste occurs.

Temperature Sensitivity

The factor influencing taste where maximum sensitivity occurs between $30-40\,^\circ\text{C}$.

Ageusia

The complete loss of taste, which may be congenital or caused by lesions of the facial or glossopharyngeal nerves.

Hypogeusia

A condition characterized by decreased taste sensitivity often resulting from various diseases.

Dysgeusia

Distorted taste perception, which is sometimes associated with temporal lobe syndrome.

Selective Taste Blindness

An inherited condition marked by a significantly increased threshold specifically for bitter tastes, while other modalities remain normal.