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 legs, and involuntary movements, such as making the heart pump blood. The nerves controlling voluntary movements are called motor nerves, and the nerves controlling involuntary actions are referred to as autonomic nerves. The afferent and efferent divisions continually interact with each other. For example, if a person were to touch a hot stove, the receptors in the skin would transmit a message of heat and pain through the sensory nerves to the brain.
The message would be processed in the brain and a reaction, such as pulling back the hand, would be transmitted via a motor nerve. NERVE DAMAGE. When an individual has a peripheral neuropathy, nerves of the PNS have been damaged. Nerve damage can arise from a number of causes, such as disease, physical injury, poisoning, or malnutrition. These agents may affect either afferent or efferent nerves. Depending on the cause of damage, the nerve cell axon, its protective myelin sheath, or both may be injured or destroyed.
CLASSIFICATION. There are hundreds of peripheral neuropathies. Reflecting the scope of PNS activity, symptoms may involve sensory, motor, or autonomic functions. To aid in diagnosis and treatment, the symptoms are classified into principal neuropathic syndromes based on the type of affected nerves and how long symptoms have been developing. Acute development refers to symptoms that have appeared within days, and subacute refers to those that have evolved over a number of weeks. Early chronic symptoms are those that take months to a few years to develop, and late chronic symptoms have been present for several years.
The classification system is composed of six principal neuropathic syndromes, which are subdivided into more specific categories. By narrowing down the possible diagnoses in this way, specific medical tests can be used more efficiently and effectively. The six syndromes and a few associated causes are listed below: Acute motor paralysis, accompanied by variable problems with sensory and autonomic functions. Neuropathies associated with this syndrome are mainly accompanied by motor nerve problems, but the sensory and autonomic nerves may also be involved. Associated disorders include Guillain-Barré syndrome, diphtheritic polyneuropathy, and porphyritic neuropathy. Subacute sensorimotor paralysis. The term sensorimotor refers to neuropathies that are mainly characterized by sensory symptoms, but also have a minor component of motor nerve problems.
Poisoning with heavy metals (e.g., lead, mercury, and arsenic), chemicals, or drugs are linked to this syndrome. Diabetes, Lyme disease, and malnutrition are also possible causes. Chronic sensorimotor paralysis. Physical symptoms may resemble those in the above syndrome, but the time scale of symptom development is extended. This syndrome encompasses neuropathies arising from cancers, diabetes, leprosy, inherited neurologic and metabolic disorders, and hypothyroidism. Neuropathy associated with mitochondrial diseases. Mitochondria are organelles—structures within cells—responsible for handling a cell’s energy requirements. If the mitochondria are damaged or destroyed, the cell’s energy requirements are not met and it can die. Recurrent or relapsing polyneuropathy.
This syndrome covers neuropathies that affect several nerves and may come and go, such as Guillain-Barré syndrome, porphyria, and chronic inflammatory demyelinating polyneuropathy. Mononeuropathy or plexopathy. Nerve damage associated with this syndrome is limited to a single nerve or a few closely associated nerves. Neuropathies related to physical injury to the nerve, such as carpal tunnel syndrome and sciatica, are included in this syndrome C. The evaluation of Sunnus’s Achillies & Babinski reflex activity: Somatic reflexes involve contraction of skeletal muscle. Somatic reflexes are the patellar reflex, the Achilles reflex, the Babinski sign. D. What type of receptor endings mediate the detection of sensation:
Nociceptors are sensory receptors that detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue. Nociceptors are free (bare) nerve endings found in the skin (Figure 6.2), muscle, joints, bone and viscera. Recently, it was found that nerve endings contain transient receptor potential (TRP) channels that sense and detect damage. The TRP channels are similar to voltage-gated potassium channels or nucleotide-gated channels, having 6 transmembrane domains with a pore between domains 5 and 6. They transduce a variety of noxious stimuli into receptor potentials, which in turn initiate action potential in the pain nerve fibers. This action potential is transmitted to the spinal cord and makes a synaptic connection in lamina I and/or II. The cell bodies of nociceptors are mainly in the dorsal root and trigeminal ganglia. No nociceptors are found inside the CNS.
Skin Nociceptors. Skin nociceptors may be divided into four categories based on function. The first type is termed high threshold mechanonociceptors or specific nociceptors. These nociceptors respond only to intense mechanical stimulation such as pinching, cutting or stretching. The second type is the thermal nociceptors, which respond to the above stimuli as well as to thermal stimuli. The third type is chemical nociceptors, which respond only to chemical substances (Figure 6.2). A fourth type is known as polymodal nociceptors, which respond to high intensity stimuli such as mechanical, thermal and to chemical substances like the previous three types. A characteristic feature of nociceptors is their tendency to be sensitized by prolonged stimulation, making them respond to other sensations as well.
Joint Nociceptors. The joint capsules and ligaments contain high-threshold mechanoreceptors, polymodal nociceptors, and “silent” nociceptors. Many of the fibers innervating these endings in the joint capsule contain neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP). Liberation of such peptides is believed to play a role in the development of inflammatory arthritis.
Visceral Nociceptors. Visceral organs contain mechanical pressure, temperature, chemical and silent nociceptors. The visceral nociceptors are scattered, with several millimeters between them, and in some organs, there are several centimeters between each nociceptor. Many of the visceral nociceptors are silent. The noxious information from visceral organs and skin are carried to the CNS in different pathways E. Are interoceptors affected?
Interoceptors detect stimuli in the internal organs such as the stomach, intestines, and urinary bladder and produce such feelings as visceral pain, nausea, stretch, and pressure.
F. Receptors mediate pain/type of pain?
Somatic sensation receptors ,itch/tickle receptors are under the tactile receptors. And his burning is a slow /rapid rate G. What would be the peripheral receptor in a intact limb to give phantom pain?
The peripheral nervous system is a nerve network radiating from the brain and spinal cord to parts of the head and body. Peripheral areas of the body include the skin surface and skeletal muscles. Sensory information, such as heat or cold or pain, travels along sensory pathways to the central nervous system. The sensory data penetrates through sensory receptors, specialized neurons or cells found in the skin and other tissues. These neurons detect internal or external changes in the environment, and convert the energy of the sensations to electrical signals that spread throughout the nervous system. Some sensations, such as reflexes, stop at the spinal cord where a synapse transmits the information to motor neurons, and the appropriate muscles are automatically activated or enervated.
But most sensory information goes on to the brain, which perceives or processes the information. Receptors for the somatosensory system are modified nerve endings of sensory neurons that have axons (see sidebar called “Nerves”) that run from the point of reception straight to the spinal cord. Receptors can also be bare nerve endings, or a nerve ending enclosed in another structure, such as a hair follicle. Sensory receptors are specialized, meaning that certain receptors pick up on certain stimuli or data.
The brain recognizes the exact type of sensor activated because each sensor travels a designated “path” to carry its specific sensory information to the right area of the brain. Types of Sensory Receptors or Cells: Mechanoreceptors – Sensory receptors that pick up changes in pressure or movement. Nociceptors – Sensory receptors that respond to pain stimuli. Thermoceptors – Sensory receptors that respond to changes in temperature. O. Because of leprosy is Sannu at a higher risk?
Recent research suggests that there is a defect in cell-mediated immunity that causes susceptibility to Leprosy aka Hansen’s disease. The region of DNA responsible for this variability is also involved in Parkinson disease, giving rise to current speculation that the two disorders may be linked in some way at the biochemical level. At highest risk are those living in endemic areas with poor conditions such as inadequate bedding, contaminated water, and insufficient diet, or other diseases that compromise immune function.
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