A. In Sannu’s case why is there both sensory loss and muscle weakness? Leprosy is a disease that has been known since biblical times. It causes skin sores, nerve damage, and muscle weakness that gets worse over time. Leprosy is caused by the bacterium Mycobacterium leprae. It is not very contagious and it has a long incubation period (time before symptoms appear), which makes it hard to know where or when someone caught the disease. Children are more likely than adults to get the disease. Leprosy has two common forms: tuberculoid and lepromatous. Both forms produce sores on the skin. However, the lepromatous form is most severe. It causes large lumps and bumps (nodules).Leprosy is common in many countries worldwide, and in temperate, tropical, and subtropical climates. About 100 cases per year are diagnosed in the United States. Most cases are in the South, California, Hawaii, and U.S. islands. Due to the constant lifestyle of unclean conditions of the water, environment and not wearing shoes placed him in the high risk category, and kept him susceptible to infection and unable to keep himself free from further exsposure/injury. B. Which events of sensation processing are most likely not functioning properly in Sannu’s leprosy? With leprosy you can have reduced sensations, either because of end organ invasion by bacilli, or by nerve trunk invasion. The nerve damage becomes clinically manifest when of the nerve fibers in a nerve trunk become non-functional . All nerve fibers are not destroyed in leprosy; some functional fibers remain even in badly damaged nerves. Regeneration of nerve fibers has been demonstrated histologically proximal to the nerve swellings. Even if the motor nerve conduction velocity is zero, the sensory nerve conduction velocity is never zero on surface recording. Nerve cells are the basic building block of the nervous system. In the PNS, nerve cells can be threadlike—their width is microscopic, but their length can be measured in feet. The long, spidery extensions of nerve cells are called axons. When a nerve cell is stimulated, by touch or pain, for example, the message is carried along the axon, and neurotransmitters are released within the cell. Neurotransmitters are chemicals within the nervous system that direct nerve cell communication. Certain nerve cell axons, such as the ones in the PNS, are covered with a substance called myelin. The myelin sheath may be compared to the plastic coating on electrical wires—it is there both to protect the cells and to prevent interference with the signals being transmitted. Protection is also given by Schwann cells, special cells within the nervous system that wrap around both myelinated and unmyelinated axons. The effect is similar to beads threaded on a necklace. Nerve cell axons leading to the same areas of the body may be bundled together into nerves. Continuing the comparison to electrical wires, nerves may be compared to an electrical cord—the individual components are coated in their own sheaths and then encased together inside a larger protective covering. Peripheral nervous system: The nervous system is classified into two parts: the CNS and the PNS. The CNS is made up of the brain and the spinal cord, and the PNS is composed of the nerves that lead to or branch off from the CNS. The peripheral nerves handle a diverse array of functions in the body. This diversity is reflected in the major divisions of the PNS—the afferent and the efferent divisions. The afferent division is in charge of sending sensory information from the body to the CNS. When afferent nerve cell endings, called receptors, are stimulated, they release neurotransmitters. These neurotransmitters relay a signal to the brain, which interprets it and reacts by releasing other neurotransmitters. Some of the neurotransmitters released by the brain are directed at the efferent division of the PNS. The efferent nerves control voluntary movements, such as moving the arms and...
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