第二章 营养学基础2.pptVIP

SECTION 5 MINERALS（矿物质）　　　一、 　Introduction Elements（元素） in human body Function of minerals in body 1. Composition of human body. 2. Maintain the pH and osmotic pressure (渗透压) of body liquids. 3. Regulating the exciting of nerve and muscle . 4. Components of prosthetic group(辅基), hormone, vitamin, protein, nucleic acid, and activator（激活剂） of enzyme. 5. The others 二、钙（Calcium） 1. Distribution of Calcium in human body 2. Function of calcium in body 1). Principal component of skeletal tissue 2). Regulating neuromuscular(神经肌肉)  excitability, maintaining  transmission of nerve impulses  (神经冲动) and heart beats. (3) Influencing enzymereaction:  Succinodehydrogenase (琥珀酸 脱氢酶). Lipase(脂肪酶),  ATPase(三磷酸腺苷酶),  proteinase(蛋白酶),  (4) Others: hormone secretion, blood 　　　 coagulation (凝结), acid-base  balance, normal colloid(胶体). 3. Absorption and Metabolism 1) Mechanism of absorption: 2) Affecting factors Age Dietary factors increasing Ca absorption: Vit. D, Lactose, Some amino acids: Arginine(精氨酸), lysine (赖氨酸) decreasing Ca absorption : phytate(植酸盐), oxalate(草酸盐), fibre, fatty acid, alcohol; thyroid hormone(甲状 腺素), cortisol(皮质醇), and antibiotics: penicillin, chloramphenical (氯霉素), neomycin (新霉素) 膳食成分对钙吸收利用的影响 3) Excretion Fecal Ca : 194 ± 73 mg/d in the American men from unabsorbed Ca and endogenous (内源性) Ca Urine Ca: diets containing 600-800 mg/d ranges between 80-250mg in urine. Sweat Ca: 20-30mg/d; 1g/d at high temp. Milk Ca: 150-300mg/d Vit.D and parathyin (甲状旁 腺素): renal reabsorption↑ Calcitonin(降血钙素): inhibiting bone loss and increasing urine Ca . Calmodulin (钙调节素): regulating the Ca in the cell.