CH. 8-senses and receptors

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CH. 8-senses and receptors
2010-04-22 17:59:04
senses receptors

CH. 8-mastication and deglutition (senses and receptors)
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  1. Tactile Sense
    sensors differ based on whether the epithelium is glabrous or not. touch receptors are broadly distributed about the body and are differentiated based on type of stimulus causing them to respond. hairy skin receptors are less critical to swallowing, as the epithelial linings of oral and pharyngeal cavities are hairless. include: meissner's and pacinian corpuscles, merkel disk receptors, ruffini endings. pg 425-426
  2. Thermal Receptors
    4 stimulations are hot, cool, warm, and cold. they are the same as pain sensors(bare nerve endings). different because different nerve endings responding to two broad classes of stimulation. differ from mechanoreceptors- mechanoreceptors respond only when stimulated, thermal have tonic(ongoing discharge). cold receptors increase firing response as temp. or stimulation drops. hot censors cease firing and pain sensors.
  3. Pain Sense(nociceptors)
    nociceptors respond directly to noxious stimulus, to noxious molecules released by injured tissue, acidity caused by injury, or direct contact with traumatic source. nociceptors respond to mechanical trauma and general destruction of tissue.
  4. Muscle Stretch and Tension Sense
    muscle stretch is sensed by muscle spindle fibers(consisting of nuclear chain fibers and nuclear bag fibers in tissue and return muscle to original position). stretch receptors found predominantly in larger muscles. mandibular elevators are richly endowed with stretch receptors(ex: facial muscles). spindle function normally inhibited during active contraction. muscle tension sensed by golgi tendon organs found in tendons and fascia- these organs respond to active contraction of muscles, serve to inhibit muscle spindle fibers.