Скачать с ютуб How Your Nose Works Animation - Sense Of Smell Video - How Do Humans Detect Odors - Olfactory System в хорошем качестве

How Your Nose Works Animation - Sense Of Smell Video - How Do Humans Detect Odors - Olfactory System

Your sense of smell warns you of dangers such as smoke and poisonous gases. It also helps you appreciate the full flavours of food and drink. Your sense of smell is 10,000 times more sensitive than your sense of taste. Music source: Emerald Therapy by Audionautix is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/...) Artist: http://audionautix.com/ Olfactory receptors You are able to detect thousands of different smells. The receptors that sense smells are called olfactory receptors. They occupy a stamp-sized area in the roof of your nasal cavity, the hollow space inside your nose. Tiny hairs, made of nerve fibres, dangle from all your olfactory receptors. They are covered with a layer of mucus. If a smell, formed by chemicals in the air, dissolves in this mucus, the hairs absorb it and excite your olfactory receptors. A few molecules are enough to activate these extremely sensitive receptors. Linked to memories When your olfactory receptors are stimulated, they transmit impulses to your brain. This pathway is directly connected to your limbic system, the part of your brain that deals with emotions. That's why your reactions to smell are rarely neutral - you usually either like or dislike a smell. Smells also leave long-lasting impressions and are strongly linked to your memories. The scent of mown grass, for example, might remind you of a childhood summer holiday, and the smell of chocolate chip cookies may make you think of your grandmother. The smells of a rose, perfume, freshly baked bread and cookies...these smells are all made possible because of your nose and brain. The sense of smell, called olfaction, involves the detection and perception of chemicals floating in the air. Chemical molecules enter the nose and dissolve in mucous within a membrane called the olfactory epithelium. In humans, the olfactory epithelium is located about 7 cm up and into the nose from the nostrils. Hair cells are the receptors in the olfactory epithelium that respond to particular chemicals. These cells have small hairs called cilia on one side and an axon on the other side. In humans, there are about 40 million olfactory receptors; in the German Shepherd dog, there are about 2 billion olfactory receptors. No one knows what actually causes olfactory receptors to react - it could be a chemical molecule's shape or size or electrical charge. The electrical activity produced in these hair cells is transmitted to the olfactory bulb. The information is then passed on to mitral cells in the olfactory bulb. The olfactory tract transmits the signals to the brain to areas such as the olfactory cortex, hippocampus, amygdala, and hypothalamus. Many of these brain areas are part of the limbic system. The limbic system is involved with emotional behavior and memory. That's why when you smell something, it often brings back memories associated with the object. As you probably know, when you have a cold and your nose is stuffed up, you cannot smell very well. This is because the molecules that carry smell cannot reach the olfactory receptors. About 2 million people in the United States have NO sense of smell. This disorder is called anosmia. A serious head injury can cause anosmia. Most likely this results in damage to the olfactory nerves as they enter the olfactory bulb. It is also possible that damage of the frontal lobes caused by a tumor or surgery can cause anosmia. Elderly people often have a reduced sense of smell. People are very sensitive to the smell of green bell pepper. This smell can be detected when it is mixed with air at only 0.5 parts per trillion! Natural gas, which many people use to heat their homes and to cook, is odorless. Because natural gas is dangerous to breathe and is explosive, it is important for people to be able to detect a gas leak. That is why gas companies add a smelly ("rotten egg smell") chemical called mercaptan to natural gas. 1 in 1,000 people are insensitive to butyl mercaptan, the stinky smell of skunks. Human olfactory system. 1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus 6: Olfactory receptor neurons Olfaction, also known as olfactics, is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, which can be considered analogous to sensory cells of the antennae of invertebrates. In humans, olfaction occurs when odorant molecules bind to specific sites on the olfactory receptors. These receptors are used to detect the presence of smell. They come together at the glomerulus, a structure which transmits signals to the olfactory bulb (a brain structure directly above the nasal cavity and below the frontal lobe).