Functions and roles of the thyroid gland

The thyroid gland is responsible for the synthesis, storage and secretion of thyroid hormones in the neck of the human body. The functions and effects of the thyroid gland have three main effects: 1. Maintaining growth and development (especially the nervous system). It is necessary for the normal development of the human body. Insufficient or excessive secretion will cause disease. When the thyroid gland is not functioning properly, physical and mental development is affected, which may lead to cretinism. When an adult's thyroid gland is underactive, it can cause myxedema. 2 Promoting the metabolism of thyroid hormones can promote the oxidation of substances, increase the decomposition and utilization of glycogen, increase oxygen consumption, increase the basal metabolic rate, and increase heat production.

The main function of thyroxine is to promote material and energy metabolism and promote growth and development processes.

①Effects on metabolism

1 Thermogenic effect: Thyroid hormones can increase the oxygen consumption rate and heat production of most tissues, especially the heart, liver, skeletal muscle and kidneys. When hyperthyroidism occurs, heat production increases, the basal metabolic rate increases, the patient prefers coolness and fears heat, and sweats easily. Conversely, when hypothyroidism occurs, the basal metabolic rate decreases, the patient prefers heat and fears coolness. Both situations cannot adapt well to changes in ambient temperature. 2. Effects on protein, sugar and fat metabolism a. Protein metabolism: When T3 and T4 are not secreted enough, protein synthesis decreases, muscles become weak, but the amount of mucin between tissues increases. It can combine with a large amount of positive ions and water to cause myxedema. Conversely, it accelerates protein decomposition, especially the protein decomposition of skeletal muscle, reduces creatinine content, increases uric acid content, and promotes bone protein decomposition, leading to increased blood calcium and osteoporosis, and increased urinary calcium excretion. b. Carbohydrate metabolism: On the one hand, thyroid hormones promote the absorption of sugar by the small intestinal mucosa, enhance glycogenolysis, inhibit glycogen synthesis, and enhance the blood sugar-raising effects of adrenaline, glucagon, cortisol, and growth hormone. On the other hand, it can also enhance the utilization of sugar by peripheral tissues and lower blood sugar. c. Fat metabolism: Thyroid hormones promote fatty acid oxidation and enhance the fat-decomposing effects of catecholamines and glucagon. T3 and T4 not only promote the synthesis of cholesterol, but also accelerate the degradation of cholesterol through the liver, but the decomposition rate exceeds the synthesis rate.

②Effect on growth and development In humans and mammals, thyroid hormones are indispensable hormones for maintaining normal growth and development, especially for the development of bones and brain. Children with hypothyroidism may present with cretinism, characterized by mental retardation and short stature.

③The impact on the nervous system not only affects the central nervous system, but also has an effect on the activities of the differentiated and mature nervous system. When the thyroid gland is hyperthyroid, the excitability increases, and the main manifestations are irritability, inattention, allergies, sentimentality, mood swings, etc. When the thyroid gland is hypothyroid, the excitability decreases, and there is memory loss, slow speech and movement, indifference and sleepiness all day long. In addition, thyroid hormones have a significant impact on the activities of the cardiovascular system, and T3 and T4 can increase the heart rate. Cardiac contractility increases, and cardiac output and work increase.