Smelly Facts Much of the thrill of kissing comes from smelling the unique odors of another's face. By simply smelling a piece of clothing, most people can tell if a woman or a man had been wearing it. Each of us has an odor that is unique, just like our fingerprints. Women have a keener sense of smell than men do. According to some sources, the stethoscope was invented not to hear the heartbeat better, but to give doctors some distance from a patient's bodily odors. Taste is closely related to smell, in fact, taste is thought to be roughly “80%” smell.

More Smelly Facts Smells stimulate memory. Students given olfactory stimulation along with a word list retain much more information and remember it longer. A smell can trigger very strong memories, positive and negative. Many smells are heavier than air and can be smelled best at ground level. We smell best if we take several short sniffs, rather than one long one. Moths can identify a single molecule by its smell. Dogs can distinguish non-identical human twins by smell, but not identical ones. Dogs can smell some cancers in people.

What do we call it? The smells of a rose, perfume, freshly baked bread and cookies...these smells are all made possible because your nose and brain work together. As with other senses, the sense organ receives a stimulus and sends information to the brain. The brain processes, perceives, and interprets this information. The sense of smell is called olfaction. Anosmia is the medical term for the complete loss of your sense of smell.

The Olfactory Apparatus: parts of the nose involved in smelling

It all starts with molecules… Odors are just small molecules that drift through the air into your nasal cavity through the nostrils and mouth. An object will have no odor unless its molecules can break free from the object and enter the air. Rocks have little smell….why? Awaiting the molecules is the olfactory apparatus, which includes all the parts of the nose involved in smelling.

How you smell: the big picture. cooking/seasoning/taste/smell. html

Once in the nasal cavity… Odor molecules first dissolve in nasal mucus. The molecules then connect to hairs on olfactory receptor cells in the olfactory membrane. Receptor cells work with certain smell types. About forty of these cells must detect odor molecules before a smell can be identified by your brain. Receptor cells send nerve signals to the olfactory bulb, a large nerve extension from the brain. Signal moves from bulb to brain by olfactory nerve.

Some vocabulary terms you ought to know... The olfactory membrane is equivalent to the retina. The olfactory receptor cells are equivalent to the rods and cones, or the hair cells in the cochlea of your inner ear. Olfactory Bulb Olfactory membrane

Smell, emotion, memory, and brain. The olfactory nerve carries the smell signal to the limbic region of the brain, where emotion and emotional memory are processed. The signal then goes to the cortex for perception and interpretation. Smell has a sort of “privileged access to our subconscious.” Smell is our most ancient of senses.

Dogs: they can smell well, but….

How come dogs have a better sense of smell than humans? Dogs have much larger olfactory membrane.  Postage stamp size vs. size of a small plate Dogs have way more receptor cells.  12 million cells vs. 200 million cells Dogs have more types of receptor cells.  500 types vs. “thousands” of types Dogs are able to distinguish more odors  10,000 odors vs. “millions” of odors

A dog’s nose The wet snout catches and dissolves odor molecules.

Taste and Tongues Watch out for this! Five tastes, not four. You can taste all flavors all over your tongue. Sweet, salt, sour, bitter, umami

This old tongue map is out of date now. 9_bad_tongue.html

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A little on taste… Molecules of food stimulate taste receptor cells to send messages to your brain. The sweet, salty, and umami buds are the least sensitive and the bitter and sour ones are the most sensitive. Taste bud

Taste apparatus parts The tongue is covered with visible bumps called papillae. These bumps are covered with microscopic taste buds. Taste buds are covered with receptor cells. Receptor cells are covered with sensory fibers that interact with taste molecules. Molecule shape determines what tastes the fibers interact with. Sort of like a key (taste molecule ) fitting in a lock (fiber).

The taste process… The tongue has…  Papillae (bumps) which have…  Taste buds which have… Taste receptor cells that have… Sensory fibers (hairs) that send… Signals along a nerve to the… Brain which perceives and interprets information.

Snakes and smell Snakes use their Jacobson's Organ. located in front of the roof of the snake's mouth, functions as an odor receptor. The forked tongue snares molecules in the air, which dissolve in the moisture of the snake's tongue. (like a dog’s snout) it inserts the tips of the forked tongue into the two awaiting openings of the Jacobson's organ where the particles are identified and analyzed.