What is the role of the gustatory system in the pathophysiology of taste and smell disorders?

Answer

Taste perception is mediated by individual taste buds, with 50-100 tightly packed cells in each bud. Taste buds are made up of modified epithelial cells and chemical receptor cells; however, the receptor cells are not direct neurons as in the olfactory system. Taste bud cells are classified into cell types I-IV and include supporting cells (types I and II), receptor cells (type III), and basal progenitor cells (type IV).^[8]These cells have a life span of approximately 10 days and arise continuously from the underlying basal cell layer in a process of constant turnover, similar to that of olfactory receptor neurons. Any bud may contain any of the receptor cells necessary to identify each different taste.

Afferent nerve branches making synaptic contact with receptor cells penetrate the base of the taste bud. Taste buds occupy papillae, which are projections embedded in the tongue epithelium. A single nerve fiber innervates multiple taste papillae, and the nerve contact exerts trophic influences on the epithelium.

The specificity of the gustatory receptor cells is determined by the epithelium in which it resides, not by the particular nerve innervating the bud. A single fiber in the chorda tympani may respond to multiple types of tastes, some tastes more than others. This ability of single nerve fibers to respond to multiple types of stimuli is referred to as broad tuning, and it is shared by the olfactory system.

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Head anatomy with olfactory nerve.
Olfactory receptors.

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Author

Eric H Holbrook, MD Associate Professor, Department of Otolaryngology, Harvard Medical School; Chief of Rhinology Division, Massachusetts Eye and Ear Infirmary

Eric H Holbrook, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Rhinologic Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: 480 Biomedical, Inc.

Coauthor(s)

Donald Leopold, MD Professor of Otorhinolaryngology, University of Vermont College of Medicine

Donald Leopold, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Allergy Asthma and Immunology, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Rhinologic Society

Disclosure: Received consulting fee from Optinose, Inc for consulting. for: Neilmed, Inc - consultant.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Ted L Tewfik, MD Professor of Otolaryngology-Head and Neck Surgery, Professor of Pediatric Surgery, McGill University Faculty of Medicine; Senior Staff, Montreal Children's Hospital, Montreal General Hospital, and Royal Victoria Hospital

Ted L Tewfik, MD is a member of the following medical societies: American Society of Pediatric Otolaryngology, Canadian Society of Otolaryngology-Head & Neck Surgery

Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA Professor of Otolaryngology, Dentistry, and Engineering, University of Colorado School of Medicine

Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American Head and Neck Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Cerescan;Cliexa, eMedevents, Neosoma, MI10<br/>Received income in an amount equal to or greater than $250 from: , Cliexa;;Neosoma<br/> Received stock from RxRevu; Received ownership interest from Cerescan for consulting; for: Neosoma, eMedevents, MI10.

Additional Contributors

Courtney A Noell, MD Consulting Staff, Department of Otolaryngology, Texas Ear, Nose and Throat Specialists

Courtney A Noell, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, Texas Medical Association

Disclosure: Nothing to disclose.

Hassan H Ramadan, MD, MSc, FACS, FARS Professor and Chairman, Director of Rhinology and Allergy Center, Department of Otolaryngology-Head and Neck Surgery, Professor, Department of Pediatrics, West Virginia University School of Medicine

Hassan H Ramadan, MD, MSc, FACS, FARS is a member of the following medical societies: American Academy of Otolaryngic Allergy, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Rhinologic Society

Disclosure: Nothing to disclose.

Christine D Cairns, MD Resident Physician, Department of Otolaryngology, Fletcher Allen Health Care, University of Vermont College of Medicine

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author Richard L Mabry, MD, to the development and writing of this article.

What is the role of the gustatory system in the pathophysiology of taste and smell disorders?

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