Olfactory System - Sense of Smell

The olfactory system is responsible for our sense of smell. This sense, also known as olfaction, is one of our five main senses and involves the detection and identification of molecules in the air. Once detected by sensory organs, nerve signals are sent to the brain where the signals are processed. Our sense of smell is closely linked our sense of taste as both rely on the perception of molecules. It is our sense of smell that allows us to detect the flavors in the foods we eat. Olfaction is one of our most powerful senses. Our sense of smell can ignite memories as well as influence our mood and behavior. Olfactory System Structures   Patrick J. Lynch, medical illustrator / Creative Commons / Wikimedia Commons Our sense of smell is a complex process that depends on sensory organs, nerves, and the brain. Structures of the olfactory system include: Nose: opening containing nasal passages that allows outside air to flow into the nasal cavity. Also a component of the respiratory system, it humidifies, filters, and warms the air inside the nose.Nasal cavity: cavity divided by the nasal septum into left and right passages. It is lined with mucosa.Olfactory epithelium: specialized type of epithelial tissue in nasal cavities that contains olfactory nerve cells and receptor nerve cells. These cells send impulses to the olfactory bulb.Cribriform plate: a porous extension of the ethmoid bone, which separates the nasal cavity from the brain. Olfactory nerve fibers extend through the holes in the cribriform to reach the olfactory bulbs.Olfactory nerve: nerve (first cranial nerve) involved in olfaction. Olfactory nerve fibers extend from the mucous membrane, through the cribriform plate, to the olfactory bulbs.Olfactory bulbs: bulb-shaped structures in the forebrain where olfactory nerves end and the olfactory tract begins.Olfactory tract: band of nerve fibers that extend from each olfactory bulb to the olfactory cortex of the brain.Olfactory cortex: area of the cerebral cortex that processes information about odors and receives nerve signals from the olfactory bulbs. Our Sense of Smell Our sense of smell works by the detection of odors. Olfactory epithelium located in the nose contains millions of chemical receptors that detect odors. When we sniff, chemicals in the air are dissolved in mucus. Odor receptor neurons in olfactory epithelium detect these odors and send the signals on to the olfactory bulbs. These signals are then sent along olfactory tracts to the olfactory cortex of the brain through sensory transduction. The olfactory cortex is vital for the processing and perception of odor. It is located in the temporal lobe of the brain, which is involved in organizing sensory input. The olfactory cortex is also a component of the limbic system. This system is involved in the processing of our emotions, survival instincts, and memory formation. The olfactory cortex has connections with other limbic system structures such as the amygdala, hippocampus, and hypothalamus. The amygdala is involved in forming emotional responses (particularly fear responses) and memories, the hippocampus indexes and stores memories, and the hypothalamus regulates emotional responses. It is the limbic system that connects senses, such as odors, to our memories and emotions. Sense of Smell and Emotions The connection between our sense of smell and emotions is unlike that of the other senses because olfactory system nerves connect directly to brain structures of the limbic system. Odors can trigger both positive and negative emotions as aromas are associated with specific memories. Additionally, studies have demonstrated that the emotional expressions of others can influence our olfactory sense. This is due to activity of an area of the brain known as the piriform cortex which is activated prior to odor sensation. The piriform cortex processes visual information and creates an expectation that a particular fragrance will smell pleasant or unpleasant. Therefore, when we see a person with a disgusted facial expression before sensing an odor, there is an expectation that the odor is unpleasant. This expectation influences how we perceive the odor. Odor Pathways Odors are detected through two pathways. The first is the orthonasal pathway which involves odors that are sniffed in through the nose. The second is the retronasal pathway which is a pathway that connects the top of the throat to the nasal cavity. In the orthonasal pathway, odors that enter the nasal passages and are detected by chemical receptors in the nose. The retronasal pathway involves aromas that are contained within the foods we eat. As we chew food, odors are released that travel through the retronasal pathway connecting the throat to the nasal cavity. Once in the nasal cavity, these chemicals are detected by olfactory receptor cells in the nose. Should the retronasal pathway become blocked, the aromas in foods we eat cannot reach odor detecting cells in the nose. As such, the flavors in the food cannot be detected. This often happens when a person has a cold or sinus infection. Smell Disorders Individuals with smell disorders have difficulty detecting or perceiving odors. These difficulties may result from factors such as smoking, aging, upper respiratory infection, head injury, and exposure to chemicals or radiation. Anosmia is a condition defined by the inability to detect odors. Other types of smell defects include parosmia (a distorted perception of odors) and phantosmia (odors are hallucinated.) Hyposmia, the diminished sense of smell, is also linked to the development of neurodegenerative diseases such as Parkinsons and Alzheimers disease. Sources Neuroscience News. â€Å"How the Emotions of Others Influence Our Olfactory Sense.†Ã‚  Neuroscience News, 24 Aug. 2017.Sarafoleanu, C, et al. â€Å"The Importance of the Olfactory Sense in the Human Behavior and Evolution.†Ã‚  Journal of Medicine and Life, Carol Davila University Press, 2009.â€Å"Smell Disorders.†Ã‚  National Institute of Deafness and Other Communication Disorders, U.S. Department of Health and Human Services, 16 Jan. 2018.

Teacher Is The Best Teacher - 1747 Words

Teachers are innately known as being influential in the lives of their students. Throughout their school experience, everyone has their favorite teacher or teachers. I certainly had my share of favorites. Even those that I didn t love still made an impact on me and we re incredibly memorable. To this day, both the good and bad (as I saw it) teachers from my past 12 years of learning have been inspirations that have shaped my desire to become a teacher. As a kindergartner, Mrs. Bryant was the best teacher a child could ask for. Though I can t remember much specific details about that first year of school, I knew I loved going to class. Mrs. Bryant always greeted me and gave me hugs in the morning. I felt as if she knew me so well; and that, despite the 25 year age gap, she was my not just my teacher but my friend. When all the kids had nap time after recess, Mrs. Bryant would let me read books quietly instead of napping since she knew I could never get myself to nap (or even just sit there pretending to for 30 minutes). I felt especially loved every day as I sat and quietly read. I have since then never completely lost the desire to be a teacher, to be as amazing as Mrs. Bryant. However, when I moved up to the big leagues of first grade, things took a complete 180. Again, my memory is fuzzy, but I still can not recall a single positive moment from that year. And every terrible instance seemed to be at the fault of Mrs. Ball. On the first day of class I used a brand newShow MoreRelatedEssay Best Teacher, Worst Teacher974 Words   |  4 PagesBest Teacher, Worst Teacher Although I have had many different types of teachers, there are two that stick out more than any others. The first was my third and sixth grade teacher. She was the best teacher I ever had. The second was my seventh grade teacher. 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Sarnath Free Essays

The Buddha went from Bodhgaya to Sarnath about 5 weeks after his enlightenment. Before Gautama (the Buddha-to-be) attained enlightenment, he gave up his austere penances and his friends, the Pancavaggiya monks, left him and went to Isipatana. [4] After attaining Enlightenment the Buddha, leaving Uruvela, travelled to the Isipatana to Join and teach them. We will write a custom essay sample on Sarnath or any similar topic only for you Order Now He went to them because, using his spiritual powers, he had seen that his five former companions would be able to understand Dharma quickly. While travelling to Sarnath, Gautama Buddha had to cross the Ganges. Having no money with which to pay the ferryman, he crossed the Ganges through the air. When King Bimbis ¤ra heard of this, he abolished the toll for ascetics. When Gautama Buddha found his five former companions, he taught them, they understood and as a result they also became enlightened. At that time the Sangha, the community of the enlightened ones, was founded. The sermon Buddha gave to the five monks was his irst sermon, called the Dhammacakkappavattana Sutta. It was given on the full-moon day of Asalha PuJa. [5] Buddha subsequently also spent his first rainy season at Sarnath[6] at the Mulagandhakuti. The Sangha had grown to 60 in number (after Yasa and his friends had become monks), and Buddha sent them out in all directions to travel alone and teach the Dharma. All 60 monks were Arahants. Several other incidents connected with the Buddha, besides the preaching of the first sermon, are entioned as having taken place in Isipatana. Here it was that one day at dawn Yasa came to the Buddha and became an Arahant. [7] It was at Isipatana, too, that the rule was passed prohibiting the use of sandals made of talipot leaves. [8] On another occasion when the Buddha was staying at Isipatana, having gone there from R ¤Jagaha, he instituted rules forbidding the use of certain kinds of flesh, including human flesh. [9] Twice, while the Buddha was at Isipatana, M ¤ra visited him but had to go away discomfited. [10] How to cite Sarnath, Papers