Sense of Smell. By: Liz, Gen, Ethan, and Meakena

Transcription

1 Sense of Smell By: Liz, Gen, Ethan, and Meakena

2 Function of smell The sense and function of smell is also called olfactometry, the testing and measurement of the sensitivity of the sense of smell. Smell is processed by the temporal lobes. The sense is part of your chemosensory system(chemical senses). The ability comes from specialized sensory cells called olfactory sensory neurons that are found high up in the nasal passage in a small patch of tissue.

3 Pathway When one smells an aroma, the scent of the chemicals travels with the air through your nose deep into the nasal cavity where it dissolves into the mucus. From there the specialized olfactory neurons pick up the scent and detect the odor. They transmit the odor to the olfactory bulbs. The bulbs have a pathway that is connected to the limbic system and the neo-cortex of the brain. The sensory receptors in the bulbs send messages directly to these two centers that are responsible for memory and emotion(limbic) and centers where the modification of conscious thought takes place(neo-cortex). These brain centers recognize odors that remind us of people, places, and events associated with the scent.

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5 Anatomy Of Smell The olfactory system consists of the olfactory receptors and the olfactory bulb. The olfactory bulb is on the inferior (bottom) side of the brain. It is supported and protected by the cribriform plate of the ethmoid bone. *Olfactory bulb-is a neural structure of the vertebrate forebrain involved in olfaction, or the sense of smell.

6 The *olfactory receptor cells are neurons that have tiny hair-like projections (cilia) extending into the mucosa of the olfactory epithelium. Signals from the olfactory cells travel to the olfactory bulb, then move on to several parts of the brain.

7 Some of the olfactory fibers travel to the *amygdala, which is part of the limbic system, a group of structures located beneath the cerebral cortex. The limbic system is linked to the perception of odour, sensations of pleasure and pain, emotions like rage, fear, sadness and sexual feelings. The majority of the olfactory fibers travel from the olfactory bulb to the orbitofrontal cortex, which is located on the underside of the frontal lobe of the brain.

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9 *Odorants-a substance giving off a smell, especially one used to give a particular scent or odor to a product. *Olfactory epithelium-pseudostr atified epithelium that contains olfactory, receptor, and nerve cells whose axons connect with the olfactory bulb of the brain.

10 Anatomy of Olfactory Epithelium

11 Diseases, Disorders, and Problems Anosmia: Lacking the sense of smell Hyposmia: Reduced ability to detect odor Parosmia: change in normal perception of odors, odors can be distorted or dramatic changes Phantosmia: sensation of an odor that isn t there

12 Dangers It s extremely dangerous and uncomfortable to lose a sense of smell. Without smell a person can t smell, -Gas leaks -Rotten food -Smoke from a fire Along with losing almost all tastes in food (taste is 80% scents), memories strongly tied with smell, and depression. -Pleasant smells like baked goods, perfume, flowers *Smell is very strongly associated with memory so when someone loses their sense of smell, it can erase memories and cause forgetfulness* *Pretty easy to lose smell, bumping your head could cause Loss of smell

13 How sense is lost There s are numerous ways to develop a sense disorder.. -smoking -head trauma -aging -exposure to certain chemicals -nasal congestion (common cold or sinus but those are usually temporary anosmia) -Nasal polyps A otolaryngologist (ENT) is the doctor one would visit if suspicion of loss of smell. A scratch and sniff test would be done using a list of common smells.

14 Interesting Facts About Sense of Smell People can detect at least one trillion distinct scents. Studies by Rockefeller University have proven this. The combination of activated nerves generates all the unique smells that we as humans can detect. Scent cells are renewed every 30 to 60 days. This is the only sense that does this. Smell is the oldest sense. Chemodetection detecting chemicals related to smell or taste is the most ancient sense. Every single animal has this sense. Studies have shown women have a better sense of smell. Dogs have nearly 44 times more scent cells than humans. Humans have five to six million odor-detecting cells as compared to dogs that have 220 million cells. Loss of sense of smell has been linked to alzheimer's. Like fingerprints, each human has their own scent. Research has shown that smell is the sense most linked to our emotional recollection. So, when linked to a product, that can reap dividends. Nose-blind is real. The sense of smell gets bored easily. When entering a bakery or florist you are very aware of the aroma but by the time you reach the check-out you will no longer be able to smell the different aromas around you. When you are asleep, your sense of smell shuts down. Your sense of smell accounts for 75-95% of the impact a flavour has. Without being able to smell the difference between onion and potato, it d be difficult to tell them apart.

15 Taste And Smell Taste itself is focused on distinguishing chemicals that have a sweet, salty, sour, bitter, or umami taste But it s the interactions between senses of taste and smell that enhance our perceptions of the foods we eat. That s why when we were younger our parents would tell us to plug our nose if we didn t want to taste the food. Olfactory information passes to adjacent parts of the orbital cortex, where the combination of odor and taste information helps create the perception of flavor.

16 Aromatherapy? Research has established that essential oils have an influence on the Limbic System in the brain which brings about changes in the brain's chemistry, and this in turn can influence our emotions. Precisely which emotion is evoked when experiencing a fragrance will of course depend on the natural chemistry of the particular oil concerned.

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19 Activity 1. Match the 2 scents together that are the same smell. 2. Guess what the scent is!

20 Sources