Taste pathway
•Download as PPTX, PDF•
113 likes•42,274 views
The document discusses the human sense of taste. It describes the five primary tastes detected by taste buds located on papillae on the tongue. Taste buds contain specialized cells that detect tastes and transmit signals through cranial nerves to the brainstem, thalamus, and gustatory cortex. Factors that influence taste include saliva, medications, disease, and aging. Disorders of taste include loss of taste and distortions or phantom tastes.
Recommended
More Related Content
What's hot
What's hot (20)
Similar to Taste pathway
Similar to Taste pathway (20)
Recently uploaded
Recently uploaded (20)
Taste pathway
- 2. CONTENTS • INTRODUCTION • PRIMARY TASTE SENSATION • TASTE BUDS • PAPILLAE OF TONGUE • TASTE PATHWAYS • APPLIED ASPECTS • CLINICAL CONSIDERATIONS • CONCLUSION • REFERENCES
- 3. INTRODUCTION • Sense of taste-allow us to separate undesirable or even lethal foods from those that are pleasant to eat. • Function of taste buds • Taste stimulate secretion of saliva and gastric juices. • Allows to select food
- 4. Primary sensations of taste 2 Sodium Receptor 2 Potassium Receptor 1 Chloride Receptor 1 Adenosine Receptor 1 Inosine Receptor 2 Sweet Receptors 2 Bitter Receptors 1 Gluatamate Receptor 1 Hydrogen Ion Receptor
- 6. SOUR TASTE Concentration of H+ ions Intensity α log of H+ ion More acidic α more sour
- 7. SALTY TASTE Elicited by ionized salts Sodium ion concentration
- 8. SWEET TASTE • Sugars • Glycols • Alcohols • Aldehydes • Ketones • Inorganic salts of lead & beryllium •Amides •Esters • Aminoacids •Small proteins •Sulfonated acids
- 9. BITTER TASTE Long chain organic substances – nitrogen Alkaloids – drugs-quinine,caffeine Deadly toxins found in poisonous plants Rejection of food
- 10. UMAMI TASTE Japanese word- ‘pleasant sevory taste’ Glutamate receptor Kikunae Ikeda in 1908 Fish, mushrooms,aging cheese, spinach, ripe tomatoes,meat extracts.
- 12. THRESHOLD FOR TASTE • Sour taste • HCl 0.0009N • Salty taste • NaCl 0.01M • Sweet taste • sucrose 0.01M • Bitter taste • quinine 0.000008 M
- 13. TASTE BUD • Goblet shaped • Diameter : 1/30 mm • Length : 1/16mm • 50 modified epithelial cells Supporting cells Gustatory cells
- 15. • Appears early – 7 to 8 weeks of IUL • Matures later after gestation • Increase in number after birth • Adults- 3000-10,000 • Children • >45yrs • Ability to Regenerate – gustatory nerve Degenerate ---taste sensation
- 16. TASTE CELLS • Mitotic division • Mature cells- lie toward centre of the bud-break up & dissolve • Life span- 10 days
- 17. HISTOLOGY OF TASTE BUD • Type 1 – long and narrow ,dark cells,irregular nucleus • Type II – long, light cells, round oval nuclei • Type III – similar to type II , dense cored vesicle in basal portion • Type IV - contacts basement membrane,doesnot extend to the taste pore - basal cell
- 18. LOCATION OF TASTE BUDS
- 22. FOLIATE PAPILLAE
- 23. MECHANISM OF TASTE SENSATION Taste cell membrane - - - - - - + + + + + + Taste substance Depolarization Receptor potential
- 25. • Generation of nerve impulses – strong immediate signal Weaker continuous signal Exposed to stimulus
- 27. Central Termination – Afferent Fibers • Facial (VII) nerve- chorda tympani – entirely gustatory • Glossopharyngeal ( IX ) – gustatory & somato sensory fibres • Vagus (X ) – superior laryngeal nerve –gustatory & chemosensory fibres
- 28. NTS ROSTARL ZONE – gustatory information CAUDAL – swallowing, respiartion, gastric motility MEDIAL LATERAL
- 29. • Three main types of neurons • ELONGATE: fusiform cell body, 2 primary dendrites • MULTIPOLAR: stellate , pyramidal soma ,3-4 primary dendrites • OVOID : small soma, 3 or more primary dendrites
- 30. PONTINE TASTE RELAY • Ascending axons bypasses – ventroposteromedial nucleus of thalamus. • Organised along dorsoventral axis • Response characteristics - NTS
- 31. THALAMUS AND CORTEX • Thalamic gustatory relay nucleus ventro medial tip ventro postero medial thalamic nucleus part of ventro basal complex • Projections further ascend – agranular insular cortex • Gustatory stimulation – cortical gustatory projection
- 33. ROLE OF SALIVA • Essential for normal taste function • Dry mouth- difficult to taste • Acts as a solvent • Fungiform – saliva from all salivary glands • Remaining papillae – von Ebner’s • Taste buds –palate,larynx,pharynx- minor salivary glands
- 34. • Feeding/drinking Muscles move food around mouth Facilitates access of solubilzed taste stimuli entirely • Significant – clefts of vallate & foliate papilla
- 35. Effect of reduced salivation • Head and Neck radiation – taste disturbances • Affect turn over of taste buds • Damage nerve terminals • xerostomia- altered taste perception
- 36. Salivary gland removal Electronmicroscopy of taste buds macrophages, large number of bacteria altered taste perception • Sjogren syndrome- reduced taste sensitivity for all 4 taste qualities
- 37. CLINICAL CONSIDERATIONS • Complete loss – aguesia • Partial loss – hypoguesia • Distortions of taste – dysguesia • Abberant taste - Abnormal stimulation – Phantom – chemosensory disorders • Vitamin A deficiency - keratinization • Gustatory hallucinations -epilepsy
- 38. • Familial dysautonomia – smooth tongue + papillae taste buds • Malignancy – anorexia • Burning mouth syndrome • Taste blindness- genetic - recognize taste • Poor oral hygiene
- 39. Incidence of taste disturbance with common medications Medication Incidence , % • Acetazolamide 12-100 • Captopril 2-7 • Lithium 5 • Procainamide 3-4 • Amiodarone 1-3 Rebecca Douglass et al, Drug-related taste disturbance A contributing factor in geriatric syndromes; Can Fam Physician 2010;56:1142-7
- 40. INVESTIGATION Possible causes • Detailed history and examination - local causes. • Haematological and biochemical investigations - nutritional and endocrine causes • Computed tomography - neurological causes • Ageing process J M Boyce, G R Shone, Effects of ageing on smell and taste; Postgrad Med J 2006; 82:239–241.
- 41. MANAGEMENT • Counselling and reassurance • Relatives or neighbours need closer involvement to check for spoiled food that if eaten could lead to food poisoning. • Flavour enhancement - salt J M Boyce, G R Shone, Effects of ageing on smell and taste; Postgrad Med J 2006; 82:239–241
- 42. CONCLUSION • Taste sensation allow us to separate lethal foods • 5 principal taste • Mainly in taste buds • Lack-anorexia, weight loss.
- 43. REFERENCES • Bradley RM: Essentials of Oral Physiology, USA,1998, Mosby • Antonio Nanci. Salivary Glands. Tencate’s Oral Histology 7th ed.Mosby .India. 2008 • G S Kumar.Salivary glands .Orban’s Oral Histology and Embryology.12th ed.Elsevier India;2007 • Arthur Guyton.The Chemical senses. Textbook of medical physiology.10th ed WB Saunders;2001
- 44. • J M Boyce, G R Shone, Effects of ageing on smell and taste; Postgrad Med J 2006;82:239–241. • Rebecca Douglass et al, Drug-related taste disturbance A contributing factor in geriatric syndromes; Can Fam Physician 2010;56:1142-7
Editor's Notes
- 13 chemical rece n taste cells nd r grpd into 5 genrl categories
- Multiple class of chemicals
- Multpl cls f chmcls
- Bitter more sensitive, provide a protective fn against many dangerous toxins n food
- Tp- fluid envmt f larynx oropharynx
- Microvilli receptr surface for taste
- PALATE
- Secnd mesngr trnsmtr substnce, g protein coupled receptor- gustducin closng f k channels
- Cell bodies Geniculate 7 petrosal 9 nodosa 10
- Send axons rostrally & other loctns n d medulla, ovoid connect locally within nts
- Neurons responding to