This document summarizes the gustatory and olfactory senses. It describes the taste buds and papillae located on the tongue and other areas that detect the five basic tastes: sweet, salty, sour, bitter, and umami. It explains the four main cell types found in taste buds and how each taste is transduced. The pathways for taste and smell sensations are outlined, from receptor cells to the brain areas involved in processing these sensations. Diagrams are included illustrating taste bud anatomy, the taste transduction mechanisms, and the gustatory and olfactory pathways in the brain.

1. Gustatory & Olfactory Senses
Dr. AniketA. Shilwant
Assistant Professor
Dept. of Kriya Sharir
GJP-IASR,CVM University

2. Gustatory Sensation
• Taste sensation – Gustatory sensation
• Organs / Structure – Taste Buds
• Taste buds – oval bodies
• Location – Present on papillae present on Tongue, Epiglottis, Pharynx,
Palate and even Proximal Part Of Esophagus
• Diameter – 50 μ to 70 μ
• In adults nearly 10000 taste buds are present.
• Types of papillae –
• Fungiform
• Filliform
• Circumvallate

3. Gustatory Sensation
• Fungiform – Rounded, present on anterior surface of tongue. Contains upto 10
taste buds.
• Filliform – Small, conical shaped over dorsum part of tongue. Contains very few
taste buds.
• Circumvallate – Larger structures present on posterior part of tongue. Arranged in
V shaped and contains upto 100 taste buds.
• Cells in Taste buds –
• Type I – Supporting cells
• Type II
• Type III – Taste receptor cell
• Type IV – Supporting cells

4. TASTE BUD WITH PAPILLAE AND CELLS PRESENT IN TASTE BUD

5. Gustatory Sensation
• Taste Sensation –
• Sweet
• Salty
• Sour
• Bitter
• Umami
• Loss of Taste Sensation – Ageusia

6. Taste Transduction
• Transduction mechanism is different in each taste receptor.
• Taste Receptors are generally - G-protein coupled receptor (GPCR).
• G protein – Gustducin

7. Taste Transduction
Sweet receptor - substances bind to GPCR and cause depolarization via IInd
messenger system (cyclic AMP)
Salt receptors - Epithelial sodium channel (ENaC)
• Sodium entry – Glutamate release – Depolarization
Sour receptor - Epithelial sodium channel (ENaC)
• Proton entry (Hydrogen) – Depolarization
Bitter receptor - GPCR
• Activates phospholipase C - Production of Inositol triphosphate
• (IP3) – Release of Calcium ions – Depolarization

8. Gustatory pathway
 Fibers from anterior 2/3rd tongue (Trigeminal N. & Facial N.)
Fibers from posterior 1/3rd tongue (Glossopharyngeal N.)
Fibers from epiglottis, palate, pharynx and other structures (Vagus N.)
 Axons of all these runs together and terminate in Nucleus of Tractus
Solitarus (NTS) in Medulla
 From NTS to Medial leminiscus and terminates in Thalamus.
 From Thalamus to Primary Gustatory Area (Area No. 43) in Parietal Lobe

9. Gustatory Pathway

11. Olfactory Sensation
• Vomero-nasal organ
• Accessory olfactory organ also c/a – Jacobson organs.
• Pheromones or Vomeropherins – Sixth Sense*
Olfactory receptor
• Location – olfactory mucus membrane which contains nearly 10 to
20 million of olfactory receptor cells
• Mucosa also contain mucus secreting – Bowman gland
• These are bipolar neuron with shorter dendrites
• Loss of smell sensation – Anosmia

12. Olfactory
Receptor

13. Olfactory pathway
• Axons of Bipolar neuron leaves nostril part
• Pierces Cribriform plate of Ethmoid bone reaches Olfactory
Bulb
• In olfactory bulb synapse with Mitral cells
• Axons of mitral cells leave olfactory bulb and forms Olfactory
Tract
• Olfactory tract run posteriorly ends in Olfactory Cortex

14. Olfactory
Pathway

15. Olfactory Pathway

16. ThankYou All !!!
Dr. Aniket A. Shilwant
Assistant Professor
Department of Kriya Sharir
GJP-IASR, CVM University
Email – ayuraniket18@gmail.com
http://ayugjac.edu.in/Staff_CV.aspx?dl=dn3Mja19480dn3Mja19
http://scholar.google.co.in/citations?user=636K2sMAAAAJ&hl=en
https://www.researchgate.net/profile/Aniket_Shilwant