Section 3 Thyroid gland Copynight e The Me Graw.Hin companies, ine. Permission required for reproduction or display. Thyroid cartilage of larynx Cricoid cartilage of larynx Thyroid gland Trachea
Section 3 Thyroid Gland
(b) Section of thyroid gland Thyroid follicle Capsule of connective tissue C cells secrete Capillary calcitonin Follicular cells secrete Colloid is a thyroid hormone glycoprotein
I. Biological actions of Thyroid Hormones T, and T, bind with nuclear receptor, activate and initiate genetic transcription mrNA protein syntheSis in cytoplasmic ribosomes general increase in functional activity throughout the body
I. Biological Actions of Thyroid Hormones ◼ T3 and T4 bind with nuclear receptor, ◼ activate and initiate genetic transcription. ---- mRNA ◼ protein synthesis in cytoplasmic ribosomes ---- ◼ general increase in functional activity throughout the body
1. On Metabolism a Calorigenic action of thyroid hormones Effect on metabolism of protein carbohydrate fat
1. On Metabolism ◼ Calorigenic action of thyroid hormones ◼ Effect on metabolism of ◼protein ◼carbohydrate ◼fat
Calorigenic action increase O, consumption of most tissues in the body increasing heat production and BMr mechanism A: Enhances Nat-K ATPase activity B: Causes the cell membrane of most cells to become leaky to Na* ions
Calorigenic action ◼ increase O2 consumption of most tissues in the body, increasing heat production and BMR. ◼ mechanism ◼ A: Enhances Na+-K+ ATPase activity ◼ B: Causes the cell membrane of most cells to become leaky to Na+ ions
+30 +10 中E -40 只 100 200 300 Thyroid hormones ug/day) FIGURE 76.5 Approximate relation of daily rate of thyroid hormone(Ti and T,) secretion to the hasal metabolic raie
on metabolism of protein Physiological level: stimulates synthesis of proteins and enzymes Hyperthyroidism: catabolism of protein, leads weigh-loss and muscle weakness Hypothyroidism: myxedema(粘液性 水肿) develops because of deposition of mucoprotein binding with positive ions and water molecules in the interstitial spaces while protein synthesis ecreases
on metabolism of protein • Physiological level: stimulates synthesis of proteins and enzymes, • Hyperthyroidism: catabolism of protein, leads weigh-loss and muscle weakness • Hypothyroidism: myxedema (粘液性 水肿） develops because of deposition of mucoprotein binding with positive ions and water molecules in the interstitial spaces while protein synthesis decreases
On carbohydrate metabolism Increase absorption of glucose from the gastrointestinal tract a Enhance glycogenolysis, and even enhanced diabetogenic effect of glucagon, cortisol and growth hormone a Enhancement of glucose utilization of peripheral tissues
On carbohydrate metabolism ◼ Increase absorption of glucose from the gastrointestinal tract ◼ Enhance glycogenolysis, and even enhanced diabetogenic effect of glucagon, cortisol and growth hormone. ◼ Enhancement of glucose utilization of peripheral tissues
On fat metabolism ■ Fatty acids accelerate the oxidation of free fatty acids increase the effect of catecholamine on decomposition of fat a decrease plasma cholesterol concentration promote synthesis increase decomposition
On fat metabolism ◼ Fatty acids: ◼ accelerate the oxidation of free fatty acids ◼ increase the effect of catecholamine on decomposition of fat. ◼ decrease plasma cholesterol concentration ◼ promote synthesis ◼ increase decomposition
2. on Growth and Development essential for normal growth and development especially skeletal growth and development a stimulate formation of dendrites, axons. myelin and neuroglia Cretinism a child without a thyroid gland growth and mental retardation
2. on Growth and Development ◼ essential for normal growth and development ◼ especially skeletal growth and development. ◼ stimulate formation of dendrites, axons, myelin and neuroglia. ◼ Critinism ◼ A child without a thyroid gland ◼ growth and mental retardation