Taste and smell
We'll finish off our exploration of sensory systems with a discussion of taste and smell.
1) Start with this video about taste:
2) Next, watch this video about smell (olfaction):
3) Read this article about an important olfactory structure: Know Your Brain - Olfactory Bulb
4) Finally, answer these questions to test your understanding:
1. What is the correct term for the small bumps that cover the tongue?
- A. taste buds
- B. papillae
- C. taste receptors
- D. microvilli
Show Answer
Correct answer: B
The small bumps that cover the tongue are sometimes mistakenly called taste buds, but the correct term for them is papillae. Taste buds are found in the walls of the papillae, with each papilla containing anywhere from a just a few to hundreds of taste buds. Each taste bud contains 50-150 taste receptor cells, which interact with the substances in the mouth through microvilli that extend into the mouth.
2. The microvilli of taste receptor cells extend through which structure to come in contact with substances in the mouth?
- A. papilla
- B. taste pore
- C. lingual gland
- D. gustatory nerve
Show Answer
Correct answer: B
Microvilli extend from taste receptor cells through an opening called the taste pore into the mouth. These microvilli come in contact with substances in the mouth that can be tasted, also known as tastants. Tastants interact with taste receptor cells through a number of different mechanisms to depolarize the cells.
3. The axons from olfactory receptor cells travel from the olfactory epithelium to this structure, forming the first cranial nerve:
- A. hippocampus
- B. olfactory bulb
- C. hypothalamus
- D. olfactory tubercle
Show Answer
Correct answer: B
The axons of olfactory receptor cells travel from the olfactory epithelium to the olfactory bulb. These axons make up the first cranial nerve, which is generally considered the shortest cranial nerve.
4. Where are olfactory receptors primarily located?
- A. olfactory bulb
- B. olfactory epithelium
- C. olfactory cortex
- D. nasal conchae
Show Answer
Correct answer: B
Olfactory receptors are located in the olfactory epithelium—a specialized area of tissue at the top of the nasal cavity. This is where odorant molecules first bind, initiating the sense of smell.
5. Which of the following is a common cell type in the olfactory bulb that receives input from olfactory receptor neurons and sends output to the olfactory tract?
- A. granule cell
- B. mitral cell
- C. Purkinje cell
- D. pyramidal cell
Show Answer
Correct answer: B
Mitral cells are one of the main output neurons of the olfactory bulb. They receive synaptic input from olfactory receptor neurons (within glomeruli) and send their axons through the olfactory tract to higher brain regions, including the olfactory cortex.
