PRACTICAL 1SENSORY RECEPTOR SENSITIVITY Example

PRACTICAL 1SENSORY RECEPTOR SENSITIVITY Example PRACTICAL 1:SENSORY RECEPTOR SENSITIVITY â€" Assignment Example > PRACTICAL 1: SENSORY RECEPTOR SENSITIVITY: Aim: To determine the characteristics of cetaceous receptors by studying variations in response of mechanoreceptors and thermoreceptors. To observe variations in localization of touch over various body parts. To observe variations in location and concentration of heat receptors. Introduction. The sensory receptors are widely classified into three categories depending with the origin of the stimulus: Namely; interoceptors, proprioceptors and the exteroceptors. This model of classification though has the limitation of revealing little regarding the sensory apparatus of the general somatic afferent. And for this matter is appropriate that we also base the classification of the kind of stimulation on which the receptor will respond to and are; the thermoreceptors, the nociceptors and the mechanoreceptors. Mechanoreceptors response to receptors or tissues is of similar mechanical deformations of touch, pressure, vibration and stretch. The sens ations recorded normally range from the random body position to touch and the orientation in space. In this Laboratory practical session, we are to observe the variation in discrimination over different body parts by deploying two-point discrimination method. Nolar, M.F. , (1987}Physiologically, the dermis of the skin has two specialized nerve endings which are the receptors for the temperature. The Krause’s end bulb is more sensitive than the receptors for heat and is specialized for cold reception. To distinguish the heat receptor from the touch receptors when the temperatures are low is always difficult and even when the temperatures are high, distinguishing them with the pain receptors is also difficult. Weinstein, S., (1968)Before going into the details of the composition of each receptor group, the significant to understand the various afferent fiber groups that work hand in hand with the various receptors kinds. There are two kinds of nerve fibers; the myelinated and the non myelinated. The myelinated nerve fibers have a much high velocity of conduction than the non-myelinated nerve fibers. The non myelinated nerve fibers are cuteneous nerves with a diameter of about 0.2 â€" 1.5 um and their conduction velocity is approximately 0.4-2.0 m/s. The stimuli sensitivity of the non-myelinated nerve fibers varies between the glabrous which are less sensitive and the glabrousskin being more sensitive. It’s the physical motion or the indentations that cause the excitement of the mechanoreceptors. Some mechanoreceptors are situated in the superficial and in the deep areas of the skin. At the superficial section, there is Merkel disk receptors and Meissner’s corpuscles. Schmidt, R.F. , (1981). Part A: Two-Point DiscriminationMethodology: 1.Blindfold the subject and ensure he/she is seated and relaxed with hands resting on a bench or arm rest. 2.Commence with a minimum separation of stimuli by using both ends of a two-point compass and stimulate the subject ’s finger. Ask the subject to report if he/she feels 1 or 2 stimuli. 3.Increase the separation distance of the compass points by 1 mm until the subject first reports 2 stimuli. RECORD the separation distance. 4.Start with a separation distance of 10 mm and progressively decrease the separation distance by 1 mm until the subject first reports one stimulus. RECORD the separation distance.