Final answer:
Olfactory receptor proteins are activated by odorant molecules. These volatile chemicals bind to receptors in the olfactory neurons, triggering our sense of smell. Humans have around 350 receptor subtypes, allowing us to detect approximately 10,000 odors.
Step-by-step explanation:
Olfactory receptor proteins are stimulated by chemicals called odorant molecules. These volatile chemicals bind to receptor proteins in the olfactory neurons to stimulate the sense of smell. Odorants are mixtures of many different molecules, which are detected when the brain integrates the signals generated by each molecule-receptor pair. In humans, the olfactory receptors are expressed by approximately 400 different genes, which is the largest number of genes coding for a single function in the human genome. These receptors are responsible for our ability to detect a wide array of odors.
The olfactory epithelium houses the olfactory receptor neurons and is located in the superior nasal cavity. The bipolar sensory neurons here have dendrites that extend into the mucus lining the cavity. As airborne molecules are inhaled, they dissolve in the mucus and interact with G protein-coupled receptor proteins on the dendrites, creating a graded membrane potential in the olfactory neurons.
Humans are capable of sensing around 10,000 different odors thanks to about 350 olfactory receptor subtypes. In comparison, animals like mice may detect more odors due to a larger number of olfactory receptor types. It's important to realize that both our senses of taste and smell contribute to our perception of flavor. The olfactory receptors are located in the mucous membrane at the top of the nose, with hair-like extensions that connect with odor molecules, initiating the scent detection process.