Immune system skeletal muscle

These disorders are all acquired conditions with no evidence of an hereditary basis. Most of them involve inflammation of the skeletal muscle itself (myositis) (Figure 17), though this may sometimes occur because of initial targeting of the muscle vasculature or connective tissue. Many instances of myositis are classed as idiopathic disorders, in that the precise mechanisms of muscle degeneration are not known, but is widely accepted that these syndromes are associated with abnormal function of the immune system. The syndromes of polymyositis (PM) and derma-... 

Amino acid metabolism is important in all tissues/organs but especially so in the liver, intestine, skeletal muscle, adipose tissue, kidney, lung, brain, cells in the bone marrow and cells of the immune system. 

Muscular system disorders related to the immune system include myasthenia gravis (MG) and tumors. MG is characterized by weak and easily fatigued skeletal muscles, one of the symptoms of which is droopy eyelids. 

MG is caused by antibodies that a person makes against their own Ach receptors hence, MG is an autoimmune disease. The antibodies disturb normal Ach stimulation to contract skeletal muscles. Failure of the immune system to destroy cancerous cells in muscle can result in muscle tumors. Benign muscle tumors are called myomas while malignant muscle tumors are called myosarcomas. 

Myasthenia gravis is a progressive disorder characterized by muscle weakness eye muscles are often the first affected. Research has shown it to be an autoimmune disease in which the victim forms antibodies to his or her nicotinic acetylcholine receptors at motor endplates. It is characterized by fatigability and weakness of the skeletal muscles, especially those of the eyes. Approximately 90% of the patients have droopy eyelids and double vision. Treatments include corticosteroids and thymectomy to reduce the actions of the immune system and anti-ChE agents such as pyridostigmine to improve the effectiveness of the receptors that remain. 

Effects of the test substance on organ systems not investigated elsewhere should be assessed when there is a reason for concern. For example, dependency potential or skeletal muscle, immune and endocrine functions can be investigated. 

Agents that inhibit steps in the steroidogenic pathway and thus alter the biosynthesis of adrenocortical steroids are discussed, as are synthetic steroids that inhibit glucocorticoid action. The effects of corticosteroids are numerous and widespread, and include alterations in carbohydrate, protein, and lipid metabolism maintenance of fluid and electrolyte balance and preservation of normal function of the cardiovascular system, the immune system, the kidney, skeletal muscle, the endocrine system, and the nervous system. 

Fig. 42.3. Interorgan amino acid exchange after an overnight fast. After an overnight fast (the postabsorptive state), the utilization of amino acids for protein synthesis, for fuels, and for the synthesis of essential functional compounds continues. The free amino acid pool is supported largely by net degradation of skeletal muscle protein. Glutamine and alanine serve as amino group carriers from skeletal muscle to other tissues. Glutamine brings NH4 to the kidney for the excretion of protons and serves as a fuel for the kidney, gut, and cells of the immune system. Alanine transfers amino groups from skeletal muscle, the kidney, and the gut to the liver, where they are converted to urea for excretion. The brain continues to use amino acids for neurotransmitter synthesis.

The expanding list of tissues that use differentiation from stem to progenitor to mature cells includes blood cells, immune system cells, central and peripheral nervous tissues, skeletal muscles, and epithelial cells. The resulting chnical stem cell transplantation could greatly increase the physician s armamentarium against degenerative diseases and the consequences of acute failures. 

Vitamin Bi, also called thiamine, is required for all tissues and high concentrations are found in skeletal muscle, heart, liver, kidneys and brain. Thiamine diphosphate (TDP) is the active form and it serves as a cofactor for several enzymes involved in carbohydrate catabolism. These enzymes are also important in the biosynthesis of many cellular constituents, including neurotransmitters, and for the production of reducing equivalents used in oxidant stress defenses (Ba 2008). Thiamine is considered an anti-stress vitamin because it strengthens the immune system and improves the body s ability to withstand stress conditions (Haas 1988). 

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