Summary
Chemoreceptors in taste buds and olfactory epithelium detect dissolved and airborne molecules.
In depth
Taste buds detect sweet, sour, salty, bitter and umami; receptors are GPCRs or ion channels. Olfactory neurons express one of about 400 receptor types; signals go directly to the olfactory bulb and limbic system, linking smell with memory. Flavour is mostly smell.
Humans have around 400 olfactory receptor genes. Smell can be lost with age or infection. Taste preferences influence nutrition.
Example: loss of smell is a symptom of some viral infections.
Taste buds (about 2000 to 8000 per person, mostly on the tongue) turn over every 10 days or so. Sweet, umami and bitter use GPCRs (T1R and T2R families, with about 25 bitter receptors), while salty and sour involve ion channels (ENaC, OTOP1). The tongue map showing regions is a myth, since all areas sense all tastes. Signals go via cranial nerves VII, IX and X to the gustatory cortex. Flavour combines taste, smell, texture and temperature.
Humans have about 400 functional olfactory receptor genes (mice about 1000), the largest gene family. Each neuron expresses one receptor, and neurons expressing the same receptor converge on the same glomerulus in the olfactory bulb (Buck and Axel, Nobel Prize 2004). Odours are coded by combinations. Smell loss (anosmia) was a symptom of COVID-19, and is also an early sign of Parkinson and Alzheimer disease.
Example: when you have a cold, food seems tasteless because the smell component of flavour is blocked.
Frequently asked questions
What is Taste and Smell?
Chemoreceptors in taste buds and olfactory epithelium detect dissolved and airborne molecules.
Which area of biology covers Taste and Smell, and how advanced is it?
Taste and Smell is one of the 54 topics in Neuroscience. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Sensory Receptors, Limbic System, Cerebral Cortex.
Can you give an example of Taste and Smell?
A blocked nose dulls taste.
What should I learn before Taste and Smell?
Work through the Beginner topics in Neuroscience first, such as Nervous System, Neuron, Central and Peripheral Nervous Systems, then return to Taste and Smell. Intermediate topics assume the Beginner vocabulary.
What topics are related to Taste and Smell?
The closest topics to Taste and Smell are Sensory Receptors, Limbic System, Cerebral Cortex, Neurodegenerative Diseases. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Taste and Smell?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Taste and Smell. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Taste and Smell different from Sensory Receptors?
Taste and Smell: Chemoreceptors in taste buds and olfactory epithelium detect dissolved and airborne molecules. Sensory Receptors: Mechanoreceptors, thermoreceptors, chemoreceptors and photoreceptors transduce stimuli into signals. Read both side by side and note what each one explains.
How should I study Taste and Smell step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Sensory Receptors and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.