Anatomy and Physiology: Special Senses – TASTE and SMELL

The olfactory receptors are extremely sensitive. Only a few molecules are required to activate them. Olfactory neurons tend to adapt rather quickly when they are exposed to unchanging stimulus of odor. This is the main reason why a woman stops smelling her own perfume but quickly picks up the scent of another person’s perfume.


The tongue is a versatile organ with specialized functions like taste and speech. Beneath a cover of taste buds, the tongue is almost entirely made up of muscle. The muscles of the tongue are essential for its bodily movement and intrinsic manipulations, required for actions like speech, articulation, deglutition or swallowing, whistling, licking, kissing and even cleaning teeth.
Taste is the brain’s interpretation of chemicals that trigger receptors on the tongue, which are housed in the taste buds. The basic chemical components, are found in foods, toxins, and other ingested matter. Unappealing tastes are usually associated with toxins, as this is a defense mechanism preventing consumption. The chemicals bind their particular receptors and initiate signaling that travels through the nerves to the brain, where they are interpreted.

Taste Buds

The taste buds are specific receptors for the sense of taste which are widely distributed in the oral cavity. Of the 10,000 taste buds that humans have, most are located in the tongue. Few are found on the soft palate and inner surface of the cheeks.

Papillae – small peg-like projections that covers the dorsal surface of the tongue. These peg-like projections are of three types namely:

  • Sharp filiform papillae
  • Rounded fungiform papillae
  • Circumvallate papillae

Taste buds are found on the sides of the circumvallate papillae but are more numerous on the fungiform papillae. When a person eats something, the specific cells that respond to the chemical dissolved in the saliva are epithelial cells called gustatory cells. Gustatory cells are surrounded by supporting cells in the taste bud. Their long microvilli, the gustatory hairs, protrude through the taste pore and when they are stimulated, they depolarize and impulses are transmitted to the brain. To carry the taste impulses three cranial nerves transports it to the gustatory cortex namely:

  • Cranial nerve VII
  • Cranial nerve IX
  • Cranial nerve X

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Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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