China
Africa
Explore chapters and articles related to this topic
Sensory System
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The sensory system can code the intensity, location and quality of a stimulus. The modality of sensation depends on the specificity of the receptor and the location of a stimulus related to the receptive field. Regions of the body that are densely innervated (lips and fingers) can provide precise information about the shape, size and position of the stimulus. A large or suprathreshold stimulus can also increase the number of neurons responding by the recruitment of more sensory units. Stimulus intensity may be coded by the frequency of impulse in each sensory unit or by the number of active sensory units. There appears to be a linear relationship between the receptor generator potential amplitude and the sensory nerve action potential frequency. The stimulus intensity may have a linear or a logarithmic (Weber–Fechner law) relationship with the frequency of action potentials in the sensory nerves.
Physiology of the nervous system
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2015
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The sensory system can code the intensity, location and quality of a stimulus. The modality of sensation depends on the specificity of the receptor and the location of a stimulus related to the receptive field. Regions of the body that are densely innervated (lips and fingers) can provide precise information about the shape, size and position of the stimulus. A large or suprathreshold stimulus can also increase the number of neurons responding by the recruitment of more sensory units. Stimulus intensity may be coded by the frequency of impulse in each sensory unit, or by the number of active sensory units. There appears to be a linear relationship between the receptor generator potential amplitude and the sensory nerve action potential frequency. The stimulus intensity may have a linear or a logarithmic (Weber–Fechner law) relationship with the frequency of action potentials in the sensory nerves.
Cognitive development – learning, knowing and problem-solving
Published in Ajay Sharma, Helen Cockerill, Lucy Sanctuary, Mary Sheridan's From Birth to Five Years, 2021
Ajay Sharma, Helen Cockerill, Lucy Sanctuary
Children gain information about the world through various sensations: vision, hearing, touch, taste, smell and sensation of movement (kinaesthetic). Sensations become perception when they connect with the stored information in memory and acquire meaning.
Safety and feasibility of transcranial direct current stimulation in amyotrophic lateral sclerosis – a pilot study with a single subject experimental design
Published in Physiotherapy Theory and Practice, 2019
Sangeetha Madhavan, Anjali Sivaramakrishnan, Sam Bond, Qin Li Jiang
The participant was a 36-year-old Hispanic man, with no other known past medical history, 7 months post-diagnosis of ALS, and 1 year after the onset of symptoms. The participant was not on any prescription medications due to lack of insurance coverage. At the time of an initial visit to the laboratory, a neurological examination revealed bilateral atrophy in the thenar, hypothenar muscles and deltoid muscles. Fasciculations were noted in the right arm, abdomen and both legs. Strength testing results, using Kendall et al. (1993) manual muscle testing grades, are reported in Table 1. Strength testing showed mild decrease in strength at the ankles and knees with a somewhat pronounced decrease at the hips. Strength in the arms was also affected, with greater weakness in the shoulder muscles, and mild weakness in elbow and hand muscles. The weakness was more prominent on the right side than the left. The participant was unable to stand from sitting without using his arms for support, but was able to walk unassisted. There were no deficits in sensation, cranial nerves, co-ordination or speech. Muscle tone was increased in bilateral upper extremities and lower extremities (Table 1). Reflexes were 3+ in bilateral biceps, triceps, knee and 4+ at ankle. Babinski’s sign was absent.
Subjective assessments of floor slipperiness before and after walk under two lighting conditions
Published in International Journal of Occupational Safety and Ergonomics, 2018
Kai Way Li, Caijun Zhao, Lu Peng, Ai-qun Liu
Floor slipperiness has been one of the major issues in studying the phenomenon of slip and fall incidences. In physics, floor slipperiness is an antonym of floor slip resistance or alternatively the friction of the floor. For human aspects, floor slipperiness is the perception of human on the status of the floor concerning the likelihood of a slip and fall incidence. It therefore involves subjective measures of the friction of the floor. Visual perception is the primary source of subjective assessment of floor slipperiness. This is natural because, when walking, people look at the floor and judge the floor slipperiness based on visual clues. Lesch et al. [7] indicated that people rely on visual cues to judge floor slipperiness and they do so consistently. In addition to visual perception, people also rely on tactual sensation and proprioceptive feedback to assess floor slipperiness. Tactual sensation of the foot provides feedback in friction especially when walking barefoot. Proprioceptive feedback related to bodily balance is obtained during movements of body segments in a gait. Information from all of these channels is integrated mentally and jointly affects the floor slipperiness judgment [8]. Tisserand [9] indicated that there is a mental model of friction limits when a person is walking. The person revises the image of friction to organize information received and then makes gait adaptation so as not to exceed those limits. Conducting subjective rating of floor slipperiness at workplaces is not complicated as compared with friction measurements. Examples of subjective rating of floor slipperiness in the field have been reported [10].
Thyrotoxic periodic paralysis: a presentation of hyperthyroidism increasing in frequency around the world
Published in Journal of Endocrinology, Metabolism and Diabetes of South Africa, 2023
His neurological examination revealed global weakness in all four limbs with proximal muscle groups being more affected than distal. Tone was noted to be reduced in all four limbs. Power was 0/5 proximally and 1/5 distally. He was unable to lift his head off the bed. Reflexes were diminished globally. Plantar response was flexor in both lower limbs. Sensation and proprioception were intact and the cranial nerves were not affected. Respiratory muscles, swallowing and bladder and bowel function were not affected. Examination of other organ systems was unremarkable.