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Chemosensor

    A '''Chemosensor''' also known as '''chemoreceptor''' is a cell (biology)|cell or group of cells that transduction (physiology)| transduce a chemical signal into an action potential There are two main classes of the chemosensor:: direct and distance Two examples of distance chemoreceptors are olfactory receptor neurons in the olfactory system and those in the vomeronasal organ that detect pheromones Examples of direct chemoreceptors include taste buds in the gustatory system and carotid body|carotid bodies that detect changes in pH inside the body

    Chemoreceptors and breathing rate

    Chemoreceptors in the medulla carotid arteries and aorta detect the levels of carbon dioxide in the blood To do this they monitor the concentration of hydrogen ions in the blood which increases the pH of the blood as a direct consequence of the raised carbon dioxide concentration
    The response is that the inspiratory centre (in the medulla) sends nervous impulses to the external intercostal muscles and the diaphragm via the phrenic nerve to increase breathing rate and the volume of the lungs during inhalation

    Chemoreceptors and heart rate

    Chemoreceptors in the medulla carotid arteries and aorta detect the levels of carbon dioxide in the blood in the same way as applicable in the Breathing Rate section
    In response to this high concentration a nervous impulse is sent to the cardiovascular centre in the medulla which will then feedback to the accelerator nerve increasing nervous impulses here and prompting the sinoatrial node to stimulate more contractions of the myogenic cardiac muscle (increase heart rate)

    Chemoreceptors and sense organs

    In taste sensation the tongue is composed of 5 different taste buds: salty sour sweet bitter and umami The salty and sour tastes work directly through the ion channels the sweet and bitter taste work through G protein-coupled receptors and the unami sensation is activated by glutamate
    Noses in vertebrates and antenna in many invertebrates act as distance chemoreceptors Molecules diffused through the air and bind to specific receptors on olfactory sensory neurons activating an opening ion channel via G-proteins
    When inputs from the environment are significant to the survival of the organism the input must be detected As all life processes are ultimately based on chemistry it is natural that detection and passing on of the external input will involve chemical events The chemistry of the environment is, of course relevant to survival and detection of chemical input from the outside may well articulate directly with cell chemicals
    For example: The emissions of a predator's food source such as odors or pheromones may be in the air or on a surface where the food souce has been Cells in the head usually the air passages or mouth have chemical receptors on their surface that change when in contact with the emissions The change does not stop there It passes in either chemical or electrochemical form to the central processor the brain or spinal cord The resulting output from the CNS (central nervous system) makes body actions that will engage the food and enhance survival
    See also: Sensory receptor