甲状腺激素有什么生理作用

    What is the physiological role of thyroid hormones?

    ( 1) on the influence of metabolic heat production effect: thyroid hormone can make the intracellular oxidation speed is increased, the increase of oxygen consumption, heat production increased, that is in the fasting state, the total heat production and oxygen consumption in nearly half the role of thyroid hormone in the results, the role of thyroid hormones " said heat effect ". The heat effect of physiological significance is that the body is maintained at a certain level of energy metabolism, regulate body temperature to the constant. Homoiothermal animal body temperature regulation, although thyroid hormone plays a leading role, but must rely on the nervous system and endocrine system, 杭州看专科甲亢医院 such as the pituitary growth hormone, adrenocorticotropic hormone, adrenal medullary hormones common to assist to complete. Thyroid hormone can improve the vast majority of tissue oxygen consumption rate, increased heat production, 1 mg of thyroid hormone can increase heat production 4185000 joules ( 1000000 cards), equivalent to 250 grams of glucose and 110 grams of fat produced heat, the effect is very obvious, but some are not affected, such as the brain, lung, spleen, gonad the thymus, lymph node, skin, etc.. In the embryonic brain may be due to thyroid hormone stimulation and increased the rate of oxygen consumption, but after birth, the brain loses the ability to respond. Hyperthyroidism patients with heat production increased, hi cool heat, while hypothyroidism when producing less heat, patients hi heat aversion to cold, are not well 杭州哪个医院甲亢adapted to the change of environment temperature. Sugar, fat, protein metabolism: glucose metabolism: the metabolism of thyroid hormone effects include physiological dose and supra-physiological doses in two aspects. Physiological doses of thyroid hormones can promote intestinal absorption of glucose and galactose, stimulates gluconeogenesis and glycogen synthesis. Super physiological doses of thyroid hormones can promote liver glycogen decomposition, accelerated glucose utilization, promote the degradation of insulin. Therefore, hyperthyroidism, with hyperglycemia and glucose tolerance curves in patients with reduced sugar, slightly more, can appear even elevated blood glucose, urine glucose. But the super physiological dose of thyroid hormone can accelerate the peripheral tissue glucose utilization, the blood glucose lowering effect. So the fasting blood glucose in patients with hyperthyroidism can still be at normal levels, glucose tolerance test can also be in the normal range. Fat metabolism: thyroid hormone has a stimulation of fat synthesis and promoting fat decomposition dual function, but the general effect is to reduce the fat storage, reducing blood lipid concentration. Isotopic tracing study of cholesterol results prove that, T4 or T3 while promoting liver tissue uptake of acetic acid, accelerated cholesterol synthesis, but the more obvious effect is enhanced cholesterol degradation, accelerated cholesterol from bile in the discharge of the hyperthyroidism, blood cholesterol is lower than normal, function low is higher than normal. Protein metabolism: thyroid hormone stimulation through the mRNA form, promotes protein and enzyme production, muscle, liver and kidney protein synthesis were increased obviously, cell number and volume increased, urine nitrogen reduction, showing a positive nitrogen balance. In contrast, T4 or T3 secretion, decreased protein synthesis, muscle weakness, but intracellular mucin increased,杭州哪个医看甲亢最好 gonads, renal tissue and subcutaneous tissue clearance water increased, causing edema, known as myxedema. Myxedema hypothyroidism in adults is a clinical feature. T4 or T3 secretion is excessive and normal secretion have the obvious difference, the protein catabolism increases greatly, urinary nitrogen increasing, negative nitrogen balance. Muscle protein catabolism in strengthening the results, so that the muscle weakness; but then the excitability of the central nervous system, continued to spread that nerve impulses, muscle subjected to frequent stimulation, performance of fiber tremor, which consume additional energy, increased basal metabolic rate is one of the important reasons. ( 2) on the development and growth of thyroid hormone effects of human growth must material, can promote the growth, development and maturity. Animal experiments show that: resection of thyroid gland, tadpole, development stopped, can turn into a frog. If in the water by adding the proper amount of thyroid hormone, the tadpoles and restore growth and become a frog. In humans, thyroid hormone can not only promote the growth and development, can promote the secretion of growth hormone and growth hormone on the organization, enhance the effect, both between existing synergy. Thyroid hormone promotes the growth, development and the role through the promotion of tissue growth, secretion, so that the increased cell volume, increased to realize, the nervous system and skeletal development is particularly important, especially in the first 4 months of the greatest influence. A patient with congenital thyroid hypoplasia of the fetus, birth length and development is basic and normal, just to the number to 3 ~ 4 months later to mental retardation, bone growth stagnation phenomenon as the main feature of the " cretinism ", this shows that over a period of time of thyroid hormone on brain and long bones the normal development of essential. Therefore, treatment of " cretinism " must seize the opportunity. ( 3) on the nervous system of the effect of thyroid hormone on central nervous system effects not only in mature, also performed in maintain its normal function, that is to say the nervous system function and development, depend on the amount of thyroid hormone regulation. Thyroid hormone too much or too little direct relationship with the development of the nervous system and functional status, in fetal and early postnatal deficiency of thyroid hormones, brain growth and maturation affected, eventually make cerebral dysgenesis, appear thereby to mental, neural and skeletal dysplasia as primary manifestation of cretinism thyroid hormone supplementation, the more as early as the more timely, nervous system damage smaller, otherwise, can cause irreversible mental disorder. For adult, thyroid hormone plays an important role in improving central nervous excitability, hyperthyroidism patient often presents with neuroticism, many words to consider, not concentrating, quick-tempered, insomnia, hands flat when slight tremors; hyperthyroidism crisis can occur when delirium, coma. But in hypothyroidism is visible with memory problems, apathy, hypoesthesia, sluggish, association and language activity decreases, drowsiness, to an adult excitatory symptoms or low functional symptoms are reversible, mostly disappeared after treatment. ( 4) the effects on the cardiovascular system, the amount of thyroid hormone for the maintenance of normal cardiovascular function necessary. An excess of thyroid hormone on cardiovascular system activity has obvious strengthening effect, manifested as increased heart rate, in a quiet state, heart rate can amount to 90 ～110 times / min, stroke effectively, increased cardiac output, peripheral vasodilation, systolic blood pressure on the high side, increased pulse pressure. However, hyperthyroidism blood circulation efficiency is actually lower than the healthy people, because of their cardiac output increased levels often exceed tissue metabolism increased demand, and even some power is wasted. As a result of long-term cardiac load is overweight, and thyroid hormone to myocardial oxygen consumption increased, myocardial ischemia, degeneration, can lead to arrhythmias, ventricular dysfunction. Conversely, thyroid hormone deficiency, hypothyroidism, see slow heart rate, cardiac output is reduced, peripheral vasoconstriction, pulse pressure becomes smaller, skin, brain, renal blood flow decrease. ( 5) on the digestive system of the effect of thyroid hormone can cause gastrointestinal emptying increases quickly, small transformation time is shortened, the visible peristalsis, appetite, food intake was significantly higher than normal, but still hungry, and obvious emaciation; the increase in stool frequency and mushy, and containing no digestion of food. As a result of thyroid hormone on the liver of a direct toxic effect, make relative hypoxia and liver cell degeneration and necrosis, which showed hepatomegaly and liver function damage, transaminase, and even jaundice. And when the thyroid hormone deficiency, hypothyroidism patients not only no appetite hyperthyroidism performance, anti see appetite to drop, due杭州看最好的甲状腺医院 to intestinal peristalsis weaken common bloating and constipation. ( 6) on water, electrolyte metabolic effects of thyroid hormone has a diuretic effect, regardless of the normal or mucinous edema patients were obviously, in diuresis while, still can promote the excretion of electrolytes. With experimental diabetes insipidus animal, if removal of the thyroid gland, which makes the urine volume decrease. Super physiological doses of thyroid hormones can promote the decomposition of protein, so that the urine potassium excreted more than sodium, together with a lot of potassium into the cell, so the hyperthyroidism is often due to excessive loss of potassium and hypokalemia. Thyroid hormone deficiency, increased capillary permeability, water, sodium and mucin retention in the subcutaneous tissue, may form a myxedema. Effect of thyroid hormone on osteoblasts and osteoclasts have excitatory effects, so that the bone turnover rate, excess thyroid hormone can cause disorders of calcium and phosphorus metabolism, causing demineralization of bone, osteoporosis, and osteitis fibrosa cystica. One in 72 cases of hyperthyroid patients are mineral metabolism study, found that 50% of patients serum diffusible calcium elevation, 30% patients with elevated serum inorganic phosphorus, 44% patients with elevated alkaline phosphatase, and these substances metabolism disorder and the degree of severity was positively associated with hyperthyroidism. ( 7) for vitamin metabolic effects of thyroid hormone is a variety of vitamin metabolism and enzymes necessary for synthesis of hormones, so it too much or too little can affect the metabolism of vitamin. Hyperthyroidism era Xie Zengqiang, the body of vitamin requirements increase, vitamin B1, B2, C, A, D, E in the tissue content decreases, the vitamin into ability also reduced coenzyme. Hypothyroidism, the serum carotene accumulation, the skin can be a special yellow sclera, but not yellow. Nicotinic acid absorption and utilization, can appear nicotinic acid deficiency. ( 8) the other endocrine glands affects the human body is an organic whole, each organ, system coordination, mutual constraints, is to maintain the homeostasis of the foundation. The physiological conditions of a gland functional activity is often influenced by multiple glands effect, at the same time it also affects multiple gland functional activity, this kind of interaction, for the maintenance of homeostasis important physiological significance. Such as thyroid hormones can promote the secretion of growth hormone, and having synergistic effect. Thyroid hormones to maintain normal sexual function and reproductive function is required, hyperthyroidism, T3 increased T4, can inhibit the secretion of estrogen, the female irregular menstruation, menstruation or amenorrhea. Hypothyroidism, can cause gonadal development and dysfunction, female visible menstrual disorders, early menorrhagia, late menstruation, or even amenorrhea, reduced fertility, once pregnancy also easy to abortion. Male patients see genital hypoplasia, secondary sexual characteristics was not obvious. Effect of thyroid hormone on adrenal cortical function has a stimulating effect, can make the adrenal hypertrophy; resection of the thyroid gland can make adrenal atrophy. Thyroid hormone excess, systemic metabolic hyperactivity, cortisol degradation accelerates, the urinary 17- excretion increased hydroxyl cortisol, and thyroid hormone low, reduced the synthesis. Long lasting increase in patients with hyperthyroidism, the organism to corticosteroids need, causing adrenal reserve is insufficient, can make adrenal cortical tissue atrophy, hypothyroidism and even failure and become one of the reasons induced hyperthyroidism crisis. Introduction of corticosteroids for replacement therapy and improve the organism's response to stress the ability, through the glucocorticoid inhibition of secretion of thyroid hormone, and inhibition of T4 into T3, can cause hyperthyroidism crisis eased. Physiological doses of thyroid hormone stimulates the adrenal medullary secretion, and can enhance the peripheral effects of catecholamines. Super physiological dose of thyroid hormone, the adrenal medulla and the nerve endings of catecholamine secretion decreased, thyroid hormone deficiency leads to hypothyroidism, increased secretion of catecholamines. Physiology indicate that thyroid hormones to maintain the normal function of pancreatic islet. Resection 杭州哪个看甲状腺节结好 of the thyroid gland can make the glucose-induced insulin secretion decreased, physiological dose of thyroid hormone can restore normal reaction. Thyroid hormone can stimulate the islet cell hyperplasia, the gland hypertrophy, increased insulin secretion, degradation accelerates, the sugar and fat utilization both have synergistic effect. Hyperthyroidism due to excess, amount of thyroid hormone stimulation, can make the function of insulin are subject to different degrees of damage, the insulin function reduction, the decrease of insulin secretion and degradation of strengthening, and thus induce or aggravate diabetes, on insulin sensitivity in patients with reduced. Insufficient production of thyroid hormones hypothyroidism, insulin secretion and degradation were reduced, and the need for insulin reduction, sensitivity to insulin increased, thus reducing symptoms of diabetes.