Examples of olfactory receptors in the following topics:
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- The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity.
- The olfactory nerves consist of a collection of many sensory nerve fibers that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate of the ethmoid bone.
- Olfactory receptor neurons continue to emerge throughout life and extend new axons to the olfactory bulb.
- The sense of smell (olfaction) arises from the stimulation of olfactory (or odorant) receptors by small molecules of different spatial, chemical, and electrical properties that pass over the nasal epithelium in the nasal cavity during inhalation.
- These interactions are transduced into electrical activity in the olfactory bulb, which then transmits the electrical activity to other parts of the olfactory system and the rest of the central nervous system via the olfactory tract.
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- The area in the nasal cavity near the septum is reserved for the olfactory mucous membrane, where olfactory receptor cells are located.
- Each functions using cilia, small hair-like projections that contain olfactory receptor proteins.
- Olfactory transduction is a series of events in which odor molecules are detected by olfactory receptors.
- Once ligands (odorant particles) bind to specific receptors on the external surface of cilia, olfactory transduction is initiated.
- In mammals, olfactory receptors have been shown to signal via G protein.
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- The olfactory epithelium is a collection of specialized olfactory receptors in the back of the nasal cavity that spans an area about 5 cm2 in humans.
- An olfactory receptor, which is a dendrite of a specialized neuron, responds when it binds certain molecules inhaled from the environment by sending impulses directly to the olfactory bulb of the brain.
- Humans have about 12 million olfactory receptors distributed among hundreds of different receptor types that respond to different odors.
- Each olfactory sensory neuron has only one type of receptor on its cilia.
- In the human olfactory system, (a) bipolar olfactory neurons extend from (b) the olfactory epithelium, where olfactory receptors are located, to the olfactory bulb.
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- Humans have about 350 olfactory receptor subtypes that work in various combinations to allow us to sense about 10,000 different odors.
- Compare that to mice, for example, which have about 1,300 olfactory receptor types and, therefore, probably sense many more odors.
- In addition to the activation of the taste receptors, there are similar receptors within the nose that coordinates with activation of the taste receptors.
- Humans detect taste using receptors called taste buds.
- Humans detect taste using receptors called taste buds.
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- Sensory receptors can be classified by the type of stimulus that generates a response in the receptor.
- During smell, olfactory receptors recognize molecular features of wafting odors.
- Cutaneous receptors are
sensory receptors found in the dermis or epidermis.
- Encapsulated receptors consist of the remaining types of cutaneous
receptors.
- A tonic receptor is a sensory receptor that
adapts slowly to a stimulus, while a phasic receptor is a sensory receptor that
adapts rapidly to a stimulus.
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- A diagram of the olfactory system is shown in .
- Pregnancy and childbirth result in a high state of plasticity of the olfactory system that may facilitate olfactory learning within the mother.
- The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via the seventh, ninth, and tenth cranial nerves.
- The structure of taste receptors in humans is shown in .
- Human olfactory system. 1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus (olfaction) 6: Olfactory receptor cells
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- These receptors respond to changes and stimuli
in the environment.
- The olfactory system is the
sensory
system used for the sense of smell (olfaction).
- In humans, olfaction occurs when odorant
molecules bind to specific sites on the olfactory receptors in the
nasal cavity.
- These receptors are used to detect the presence of smell.
- They
come together at a structure (the glomerulus) that transmits
signals to the olfactory bulb in the brain.
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- Some sensory receptors can be classified by the physical location of the receptor.
- Our brains commonly receive sensory stimuli from our visual, auditory, olfactory, gustatory, and somatosensory systems.
- Sensory receptors code four aspects of a stimulus:
- Receptors are sensitive to discrete stimuli and are often classified by both the systemic function and the location of the receptor.
- Sensory receptors are found throughout our bodies, and sensory receptors that share a common location often share a common function.
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- It collects and
sends these vibrations to receptor cells.
- It contains the receptors responsible for detecting
molecules that are small enough to smell.
- These receptor neurons then synapse
at the olfactory cranial nerve, which sends the information to the olfactory
bulbs in the brain for initial processing.
- There are specialized receptors for cold (declining temperature) and heat.
- The cold receptors infer wind direction, an important part in the animal's sense of smell.
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- This takes place at the sensory receptor.
- Receptor potentials are graded potentials: the magnitude of these graded (receptor) potentials varies with the strength of the stimulus.
- For example, touch receptors, light receptors, and sound receptors are each activated by different stimuli.
- Although perception relies on the activation of sensory receptors, perception happens, not at the level of the sensory receptor, but at the brain level.
- All sensory signals, except those from the olfactory system, are transmitted though the central nervous system: they are routed to the thalamus and to the appropriate region of the cortex.