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Olfactory receptors (ORs), also known as odorant receptors, are chemoreceptors expressed in the cell membranes of olfactory receptor neurons and are responsible for the detection of odorants (for example, compounds that have an odor) which give rise to the sense of smell.
Sensory organs are organs that sense and transduce stimuli. Humans have various sensory organs (i.e. eyes, ears, skin, nose, and mouth) that correspond to a respective visual system (sense of vision), auditory system (sense of hearing), somatosensory system (sense of touch), olfactory system (sense of smell), and gustatory system (sense of taste).
The olfactory system, or sense of smell, is the sensory system used for olfaction (i.e., smelling). Olfaction is one of the special senses directly associated with specific organs. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory ...
The Lady and the Unicorn, a Flemish tapestry depicting the sense of smell, 1484–1500. Musée national du Moyen Âge, Paris.. Early scientific study of the sense of smell includes the extensive doctoral dissertation of Eleanor Gamble, published in 1898, which compared olfactory to other stimulus modalities, and implied that smell had a lower intensity discrimination.
Aside from an external nose structure, some primates contain a vomeronasal organ to detect odorants of higher molecular weight. [23] Genomic analysis has asserted that vomeronasal organ receptors became impaired approximately 23 million years ago in primate evolution, before the advent separation of Old World monkeys and hominoids.
They also sense decrease in partial pressure of O 2, but to a lesser degree than for pCO 2 and H + ion concentration. The chemoreceptor trigger zone is an area of the medulla in the brain that receives inputs from blood-borne drugs or hormones, and communicates with the vomiting center (area postrema) to induce vomiting. [citation needed]
Sense organs are transducers that convert data from the outer physical world to the realm of the mind where people interpret the information, creating their perception of the world around them. [ 1 ] The receptive field is the area of the body or environment to which a receptor organ and receptor cells respond.
The vibration theory of smell proposes that a molecule's smell character is due to its vibrational frequency in the infrared range. This controversial theory is an alternative to the more widely accepted docking theory of olfaction (formerly termed the shape theory of olfaction), which proposes that a molecule's smell character is due to a range of weak non-covalent interactions between its ...