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Encyclopedia > Olfactory system

The olfactory system is the sensory system used for olfaction. The accessory olfactory system senses pheromones. The olfactory system is often spoken of along with the gustatory system as the chemosensory senses because both transduce chemical signals into perception. Linda B. Buck and Richard Axel won the 2004 Nobel Prize in Physiology or Medicine for their work on the olfactory system. (See also sense) A sensory system is a part of the nervous system that consists of sensory receptors, neural pathways, and those parts of the brain responsible for processing the information. ... Olfaction, the sense of odor (smell), is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ... Fanning honeybee exposes Nasonov gland (white-at tip of abdomen) releasing pheromone to entice swarm into an empty hive A pheromone is any chemical produced by a living organism that transmits a message to other members of the same species. ... The gustatory system is the sensory system that uses taste buds (or lingual papillae) on the upper surface of the tongue to provide information about the taste of food being eaten. ... In physiology, transduction is the conversion of a stimulus from one form to another. ... PSYCHOLOGY In psychology and the cognitive sciences, perception is the process of acquiring, interpreting, selecting, and organizing sensory information. ... Linda B. Buck, Ph. ... Richard Axel, M.D. (born July 2, 1946, New York City) is an American scientist whose work on the olfactory system won him and Linda B. Buck, then a post-doctoral scientist in his research group, the Nobel Prize in Physiology or Medicine in 2004. ... 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... List of Nobel Prize laureates in Physiology or Medicine from 1901 to the present day. ...


Anatomy

The olfactory system is made up of a number of different areas of the brain. Here is a partial list of some of the brain structures involved: Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ...

An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction cell for olfaction in the olfactory system. ... The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. ... The nasal cavity is a large air-filled space above and behind the nose in the middle of the face. ... The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. ... The nasal cavity is a large air-filled space above and behind the nose in the middle of the face. ... The vomeronasal organ (VNO) or Jacobsons organ (sometimes misspelled Jacobsens) is an auxiliary olfactory sense organ in some vertebrates, all of which are tetrapods. ... The olfactory nerve is the first of twelve cranial nerves. ... Vesalius Fabrica, 1543. ... In anatomy of animals, the piriform cortex, or pyriform cortex is a region in the brain. ... Location of the amygdala in the human brain The amygdala (Latin, corpus amygdaloideum) is an almond-shaped set of neurons located deep in the brains medial temporal lobe. ... The entorhinal cortex (EC) is an important memory center in the brain. ...

Function

The olfactory system must accomplish several tasks:

  • Create a representation of the odor
  • Determine the concentration of the odor
  • Distinguish a new odor from the background environmental odors
  • Identify the odor across different concentrations
  • Pair the odor with a memory of what the odor represents

To accomplish all of these functions, the olfactory system uses many areas of the brain. Representations of the odor may be encoded by space (a pattern of activated neurons across a given olfactory region corresponds to the odor), time (a pattern of action potentials by multiple neurons corresponds to the odor) or a combination of the two. Scientists debate whether the odor code is primarially temporal or spatial. Neurons (also called nerve cells) are the primary cells of the nervous system. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ...

Vesalius' Fabrica, 1543. Human Olfactory bulbs and Olfactory tracts outlined in red

In mammals, odorants are inhaled through the nose where they contact the olfactory epithelium. Olfactory receptor neurons in the olfactory epithelium transduce molecular features of the odorants into electrical signals which then travel along the olfactory nerve into the olfactory bulb. Axons from the olfactory sensory neurons converge in the olfactory bulb to form tangles called glomeruli (singular glomerulus). Inside the glomulerus, the axons contact the dendrites of mitral cells and several other types of cells. Mitral cells send their axons to a number of brain areas, including the piriform cortex, the medial amygdala, and the entorhinal cortex. Image File history File links 1543,Vesalius'OlfactoryBulbs. ... Image File history File links 1543,Vesalius'OlfactoryBulbs. ... Andreas Vesalius (portrait from the Fabrica). ... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu† Homo sapiens sapiens Homo (genus). ... Vesalius Fabrica, 1543. ... Human nose in profile The Nose is a story by Gogol and an opera by Dmitri Shostakovich. ... The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. ... An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction cell for olfaction in the olfactory system. ... The olfactory nerve is the first of twelve cranial nerves. ... Vesalius Fabrica, 1543. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... The glomerulus (plural glomeruli) in olfaction is structure in the olfactory bulb. ... (The term dendrite may also refer to the metallurgical dendrite. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In anatomy of animals, the piriform cortex, or pyriform cortex is a region in the brain. ... Location of the amygdala in the human brain The amygdala (Latin, corpus amygdaloideum) is an almond-shaped set of neurons located deep in the brains medial temporal lobe. ... The entorhinal cortex (EC) is an important memory center in the brain. ...

Amygdala location in each hemisphere of the human brain
Amygdala location in each hemisphere of the human brain

The piriform cortex is probably the area most closely associated with identifying the odor. The medial amygdala is involved in social functions such as mating and the recognition of animals of the same species. The entorhinal cortex is associated with memory. The exact functions of these higher areas are a matter of scientific research and debate. Image File history File links Location of the Amygdala in the Human Brain The figure shows the underside (ventral view) of a semi-transparent human brain, with the front of the brain at the top. ... Image File history File links Location of the Amygdala in the Human Brain The figure shows the underside (ventral view) of a semi-transparent human brain, with the front of the brain at the top. ... In anatomy of animals, the piriform cortex, or pyriform cortex is a region in the brain. ... Location of the amygdala in the human brain The amygdala (Latin, corpus amygdaloideum) is an almond-shaped set of neurons located deep in the brains medial temporal lobe. ... The entorhinal cortex (EC) is an important memory center in the brain. ...


Clinical implications

Damage to the olfactory system can occur by traumatic brain injury, cancer, inhalation of toxic fumes, or neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. These conditions can cause anosmia. Doctors can detect damage to the olfactory system by presenting the patient with odors via a scratch and sniff card or by having the patient close their eyes and try to identify commonly available odors like coffee or peppermint candy, Brain damage or brain injury is the destruction or degeneration of brain cells. ... When normal cells are damaged beyond repair, they are eliminated by apoptosis. ... Anosmia is the lack of olfaction, or a loss of the sense of smell. ...

Sensory system - Olfactory system - edit
Olfactory bulb | Olfactory nerve | Olfactory epithelium | Glomeruli | Olfactory mucosa | Olfactory receptor neurons | Mitral cells | Piriform cortex
Nervous system - Sensory system - edit
Special sensesVisual system | Auditory system | Olfactory system | Gustatory system
Somatosensory systemNociception | Thermoreception | Vestibular system |
Mechanoreception (Pressure, Vibration & Proprioception)

  Results from FactBites:
 
OLFACTORY SYSTEM - LoveToKnow Article on OLFACTORY SYSTEM (4796 words)
The olfactory system consists of the outer nose, which projects from the face, and the nasal cavities, contained in the skull, which support the olfactory mucous membrane for the perception of smell in their upper parts, and act as respiratory passages below.
In mammals the olfactory chamber of the nose is variously developed; most of them are macrosmatic, and have a large area of olfactory mucous membrane; some, like the seals, whalebone whales, monkeys and man are microsmatic, while the toothed whales have the olfactory region practically suppressed in the adult, and are said to be anosmatic.
It is parleepening of the olfactory ticularly common in young girls at the ir relation to the herni- time of puberty, being a form of vicarious Is of the fore-brain, menstruation.
Olfactory system - Wikipedia, the free encyclopedia (460 words)
The olfactory system is the sensory system used for olfaction.
The olfactory system is often spoken of along with the gustatory system as the chemosensory senses because both transduce chemical signals into perception.
Outside the brain, olfactory receptor neurons reside on the olfactory epithelium in the nasal cavity:
  More results at FactBites »

 
 

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