{"id":2967,"date":"2025-09-04T13:36:00","date_gmt":"2025-09-04T17:36:00","guid":{"rendered":"https:\/\/earthmoves.vassarspaces.net\/?p=2967"},"modified":"2025-09-04T13:36:02","modified_gmt":"2025-09-04T17:36:02","slug":"ever-smelled-happy","status":"publish","type":"post","link":"https:\/\/earthmoves.vassarspaces.net\/?p=2967","title":{"rendered":"Ever smelled “Happy”?"},"content":{"rendered":"\n

Happy is a perfume that my daughter used to wear sometimes when she was a kid. She got small bottles of Happy from my mother. It kinda does smell like Happy, I think. Or, at least, it conjures some happy times.<\/p>\n\n\n\n

Our sense of smell is intimately tied to our emotions and memory. It’s evolutionarily ancient and, incredibly, still so mysterious. Let’s dive into a little neurobiology of olfaction (our sense of smell).<\/p>\n\n\n\n

Our sensory systems are crucial to our ability to detect and respond to signals in the outside world. We have nine senses (that’s right- nine<\/mark><\/strong>!): vision, hearing, balance\/head movement, proprioception (where our body parts are in space), taste, olfaction, pain, touch and temperature. NINE Senses- so cool.<\/p>\n\n\n

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Image from: https:\/\/www.facebook.com\/groups\/mikerielly<\/a><\/figcaption><\/figure>\n<\/div>\n\n\n

For us humans, our ability to smell is thanks to our olfactory epithelium, which is in our noses. The receptor cells that detect odors (chemicals that are in the air- called volatile odorants) are called chemoreceptors, cells embedded in a sheet-like membrane. These chemical-detecting neurons have proteins on their surfaces that interact with specific molecules diffusing through our mucus layer. We can detect about 10,000 different odorants and most substances are composed of complex mixtures of many different odorants. Think about a perfume- elements of rose, cinnamon, etc, etc. Each chemical interacts with a specific odorant receptor. Here’s a pic that shows how our olfactory system is organized (from my human physiology lecture notes and textbook):<\/p>\n\n\n

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A close-up picture shows how the olfactory sensory neurons interact with the next line of neurons that send signals farther into the brain (also from the textbook I use):<\/p>\n\n\n\n

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As you work through the pictures above, you’ll notice that the sensory neurons (chemoreceptors) have tiny branches that reach out of the nasal epithelium (nasal membrane) and spread out in the mucus layer in your nose (which has the #4 in the pinkish layer in the picture above). An odor molecule from something you are sniffing (suspended in the air you breathe in) has to be carried into the nasal passages and then dissolve into the mucus to reach the receptors. Ever notice that when you sniff to try to identify an odor, particularly a faint odor, you sniff fast and deeply? You try to create an inward air current and multiple puffs of this air to try to get more of the odorant chemicals farther into your nose. If you have thick mucus, like when you have a cold or allergies, it’s much harder to detect odors.<\/p>\n\n\n\n

Anyway, these sensory cells directly interact with the chemicals, which explains why these cells are so vulnerable to toxins that you inhale.<\/p>\n\n\n\n

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https:\/\/www.mdpi.com\/1424-8220\/23\/13\/6164<\/a><\/p>\n\n\n\n

When the chemical interacts with the receptors on the sensory neurons, that will cause signals from the sensory cells to the neurons in the olfactory bulb at the base of the brain and those signals travel along the olfactory nerve into the brain. The olfactory nerves split up and send their signals to the olfactory cortex (thought to be where the odors are identified), and also to areas involved in emotions and memory. Think of the smells coming from a bakery. You can identify the aromas of breads, maybe cookies. Maybe hints of vanilla or baker’s yeast. These odors are complex mixtures of chemicals and somehow our olfactory system can identify different components, and also give you that yummy feeling of home-cooked blueberry scones or birthday cakes or a memory of a time you had a special coffee cake on Christmas morning with your mom.<\/p>\n\n\n\n

Not all odors are happy, of course. I still remember (and can recognize even 40 years later) the putrid odor of a decaying corpse that was discovered in the trunk of a car in a city. The car was brought to the university hospital department of forensic science where there was a renowned forensic scientist …(like a real life Dr. Quincy). The police parked the car in a small courtyard near an elevator (that ran right up past the lab where I was doing my PhD research). The vomit-inducing reek filled the elevator (and the entire shaft) and no one could use that elevator for weeks. Disgusting, horrifying odor I’ll never forget.<\/p>\n\n\n\n

Loss of smell loses much more<\/h2>\n\n\n\n

It is really common to suffer a reduced sense of smell (according to a recent article published in The Neuroscientist<\/em> (Reichert and Schopf, 2018: 24:22-35)), yet you don’t really hear much about it. That all changed with the Covid-19 pandemic, where a profound but mostly temporary loss of smell was one of the key identifying symptoms, especially in the early days of the scourge. Thereafter, the public began to learn more about other conditions where a loss of smell is an important manifestation, like Parkinson’s disease and Alzheimer’s disease and even traumatic brain injury. Turns out about 20% of people suffer a reduction or outright loss of smell, with a higher percentage of smell loss as we age. Given the massive numbers of human-made industrial chemicals that are in the air around us all the time, it’s not surprising that our olfactory system is under assault, even if we cannot identify particular smells. Those volatile chemicals also gain access to our olfactory sensory neurons.<\/p>\n\n\n\n

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When you can’t smell, food is not appealing and eating is really tough. Without smell, taste perception is blunted and mostly what you’re left with is texture. When my father was treated for non-Hodgkin’s lymphoma, the radiation treatments damaged his ability to taste and smell and he thought everything was like cardboard or sand. He hated eating. His senses of smell and taste never fully recovered, but did improve a little bit over time. When you can’t smell, you won’t notice possible gas leaks or smoke from fires, or when food is rotten. I had a friend who had no sense of smell (called anosmia) and he once didn’t realize he had food burning in a skillet on his stove until it had burst into an oil fire.<\/p>\n\n\n\n

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Smell also affects our mood, social behavior and memory processing. Virtually any odor you encounter conjures a memory, or a feeling. There’s a lot more to a smell than just the chemical that sends a signal into your brain. There’s a huge industry surrounding the power of smell to affect mood and memory. The perfume industry is the oldest, perhaps. But, aromatherapy, candles, laundry detergents, personal care products and much more all exploit the mood-setting effects of odorants. The scents are potently profitable. What happens when you walk past an Abercrombie and Fitch store at the mall? Does the smell of fried fish or freshly baked bread wafting across the parking lot draw you into the grocery store or influence your purchases?<\/p>\n\n\n\n

Bottom line: Our sense of smell (olfaction) is really important. And, this system is designed to be on the front lines of our interactions with our chemical world. It’s not surprising that these sensory cells are vulnerable to toxic chemicals. Toxic chemicals in the food we eat, pesticide residues, preservative chemicals, can all damage our sensory neurons. Toxic chemicals in personal products from perfume to shampoo to aromatherapy candles can also damage these sensitive cells.<\/p>\n\n\n\n

What are these chemicals? Much more on this to come. But, back to Happy.<\/p>\n\n\n\n

Happy is made and marketed by Clinique.<\/p>\n\n\n\n

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Happy is said to have “key notes of ruby red grapefruit, spring mimosa, bergamot and Hawaiian wedding flower. Ahhhhh. It’s like they are creating a memory in creating a scent.<\/p>\n\n\n\n

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This newsletter is devoted to explaining how biology works and how it is relevant to our daily lives. Most of us stopped learning about biology in high school or even middle school. And the way we learned it was as isolated concepts and vocabulary to memorize. I hope that this newsletter helps you rekindle that love of biology and might even help with better understanding of some of the important biology all around us. Please share this with anyone you think might want to take a look.<\/p>\n\n\n\n

Thanks for reading!<\/mark><\/p>\n","protected":false},"excerpt":{"rendered":"

Happy is a perfume that my daughter used to wear sometimes when she was a kid. She got small bottles of Happy from my mother. It kinda does smell like Happy, I think. Or, at least, it conjures some happy times. Our sense of smell is intimately tied to our emotions and memory. It’s evolutionarily…<\/p>\n

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