Sannu's Story

Topics: Nervous system, Sensory system, Action potential Pages: 5 (1323 words) Published: April 23, 2013
Unit 8. Case Study 1. Sannu’s Story
Sannu has contracted Leprosy. As a sixteen year old teenager, it is hard to pin point when he was infected since Leprosy has a long incubation period. As a small boy traveling barefoot along trails in his village, Sannu’s body has already adapted to his living conditions. Sannu’s feet are tough and calloused. As Sannu ages, so does his Leprosy infection progress. The infection will cause neuropathy in his extremities which will lead to many injuries to his feet and hands. The wounds acquired will be infected for weeks or even months without treatment. The neuropathy caused by the Leprosy infection is characterized by causing a decrease in sensation in the extremities, muscle weakness, and numbness. Sannu’s feet that have been toughened by his environment and life style have been further injured due to lack of sensation and medical treatment. In an attempt to keep his feet clean to aide the healing of his infections, Sannu is more than likely maintaining a sedentary life style. This life style along with the progression of the Leprosy infection will weaken Sannu’s muscles.

A feature common to all forms of Leprosy is nerve infection. Nerve damage appears to result from the multiplication of bacilli within Schwann cells and damage to the perineurium. Most of the deformities occurring from Leprosy are in fact due to trauma or a secondary infection. In a Leprosy infection one of the first symptoms are anesthesia to heat and cold. Leprosy affects the peripheral nervous system by attacking the myelin sheath surrounding the axons which affects the reliability and speed of nerve impulses. In other words, the nerve fibers are no longer insulated and nerve impulses cannot be conducted efficiently. There are different types of sensory receptors located throughout the body and are designed based on a selective stimulus response. The appropriate receptive field is stimulated within a sensory receptor producing a response. In Sannu’s condition this action is delayed or absent due to the damage of his free nerve endings. Free nerve endings detect pain, temperature, and touch as well as tickle and itch. Sannu’s encapsulated nerve endings are also damaged. Encapsulated nerve endings detect pressure, vibration, and touch sensations.

When Dianna performed the tests to check Sannu’s Achilles tendon and Babinski’s reflex, she was evaluating his somatic senses. Somatic senses involve sensations such as touch, pressure, and pain as well as temperature perception. These are all affected in Leprosy infection.

In Sannu’s case he has also lost the sensations of touch, pressure, and pain in his feet and hands due to the affects of leprosy on his nociceptors, mechanoreceptors, proprioceptors, and exteroceptors. These sensations are also present in the sensory receptors free nerve endings and encapsulated nerve endings.

Sannu’s interoceptors would not be affected in a Leprosy infection because interoceptors pertain to the body’s internal environment. Mycobacterium leprae grow best in relatively cool areas of the body such as: the skin, peripheral nerves, the mucosa of the upper respiratory tract as well as the chamber of the eye and in severe untreated cases the testes and eventually other vital organs. Leprosy affects the exteroceptors of the external surface of the body.

Nociceptors are the receptors of pain and are located in all tissues of the body with an exception of the brain. Proprioceptors do no adapt very much, this is why Sannu still feels pain in his leg that has been amputated. Sannu’s pain is slow pain. Slow pain is referring to pain that is chronic, burning, aching, or throbbing.

The peripheral receptors activated during a stimulus are the nociceptors. Like other cutaneous and subcutaneous receptors, Nociceptors transduce a variety of stimuli into receptor potentials. Also, like other somatic sensory receptors, Nociceptors arise from cell bodies in dorsal root ganglia that send one axonal...
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