Module B1: Senses
Precise and accurate use of anatomical, physiological, and medical terminology both in oral and written form is an essential part of most Health Professions programs and an important skill to learn. In this course, you are expected to fully understand and correctly use each of the following terms from this module. Consult your textbook, module book, and lecture notes to be able to define and correctly use each of the following terms. Print or save this file so that you can add definitions, examples, and notes on proper usage for all terms.
Sensory receptor- sensitive to environmental changes and ititiate AFFERENT nerve impulses to carry sensory info to CNS.
Sense organ-nerve tissue surrounded by other tissues that are designed to respond to certain stimuli.
Transduction-converts one form of energy to another,=fundamental purpose of sensory receptors. (Converts stimulus energy (light, heat, touch) into nerve signals)
Action potential a large depolarizing voltage change in a plasma membrane that is conducted along the membrane of a neuron or muscle cell.
Graded potential a local voltage change in plasma membrane that varies, intensity is dependent upon stimulus strength and distance traveled
Threshold the minimum amount of stimulus needed to generate an action potential
Receptor potential a graded potential initiated by sensory stimulus
Sensation-perception resulting from sensory stimulation.
Modality-thermoreceptors, photoreceptors, nociceptors, chemoreceptors, and mechanoreceptors.
Sensory projection-sensory cortex projects a sensation back to the region of stimulation, se we can pinpoint t exactly where the sensation is coming from.
Sensory adaptation sensory receptors adjust to continuous stimulation so that impulses are triggered at slower rates. In addition, the stimuli are filtered out in the brain so the conscious brain becomes less aware of them. (Smell in a room, clothing, and background noise)
Nociceptors-2 types of receptors; different types of pain sensations; fast pain=myelinated, 12-30 m/second, sharp, localized, stabbing pain. SLOW pain-unmyelinated fibers, 0.5-2 m/second. Long-lasting, dull diffuse.
Chemoreceptors-Changes in chemical concentration
Mechanoreceptors mechanical forces
Proprioceptors tension in muscles and tendons
Special senses these are senses with receptors in complex sensory organs of the head. These include smell, taste, hearing, static and dynamic equilibrium, and vision.
Free nerve endings- general touch and pressure. Between epithelial cells.
Tactile (Meissner) corpuscles- light touch and texture. Are small, oval masses within CT, especially numerous in hairless regions of skin, (lips, fingertips, palms, soles, nipples, external genitalia)
Lamellar (Pacinian) corpuscles; - heavy, deep pressure, and vibration. Are larger, located in deeper subQ tissue. Especially in hands, feet genitalia, breasts, tendons, ligaments.
Referred pain when sensations produced-feel like they are coming from some other part (heart attack). It’s because pain sensations from VISCERA are often routed through common nerve pathways shared by sensory nerves supplying other receptors, such as the skin.
Phantom pain- pain that is perceived in a limb that has been amputated
Gustation the sensation of taste
Taste bud- consist of taste receptor cells and supporting cells. Taste cells are located on the tongue, roof of mouth, cheek lining, and the walls of the pharynx. Each bud has approx. 60-100 taste cells. TASTE CELLS HAVE TASTE HAIRS that are SENSITIVE TO particular, dissolved chemicals. CHEMICALS BIND TO THE SPECIFIC RECEPTOR SITES ON TASTE HAIRS-TRIGGERS IMPULSES TO THE BRAIN. ARE 5 PRIMARY KINDS OF CELLS KNOWN. EACH SENSITIVE TO CERTAIN CHEMICALS.
Taste (gustatory) cells SWEET, SOUR, SALTY, BITTER AND UMAMI. ALSO ALKALINE AND METALLIC.