Expanded Nutrition Key Notes for Exam (Bilingual)
Purpose of Food 摄食的目的
Provide energy for physical and metabolic activities 提供体力与新陈代谢能量
Support growth and repair of cells and tissues 支持生长及修复组织与细胞
Maintain good health and immune system 维持身体健康与免疫系统
Regulate body processes (e.g., temperature, pH balance) 调节身体机能如体温与酸碱平衡
Carbohydrates 碳水化合物
Classified as monosaccharides, disaccharides, polysaccharides 分为单糖、双糖、多糖
Monosaccharide: glucose used in respiration 单糖如葡萄糖用于细胞呼吸
Disaccharide: e.g., sucrose = glucose + fructose (condensation reaction 缩合反应)
Polysaccharide: starch (plants), glycogen (animals), cellulose (fibre)
Function: main energy source (16kJ/g), converted to glycogen/fats for storage
Excess leads to obesity, diabetes, dental caries 摄取过多导致肥胖、糖尿病、蛀牙
Proteins 蛋白质
Made up of amino acids (20 types; 9 essential) 由20种氨基酸组成（其中9种必需）
Protein functions: growth, repair, enzymes, hormones, antibodies
Sources: meat, eggs, dairy, legumes 蛋白质来源：肉类、蛋、奶制品、豆类
Deficiency: Kwashiorkor (edema), Marasmus (severe wasting) 缺乏症：水肿、消瘦
Fats 脂肪
Types: saturated (animal), unsaturated (plant oils, fish oils)
Function: energy source (38kJ/g), absorb fat-soluble vitamins (A, D, E, K)
Forms cell membranes, protects organs, insulates heat
Excess intake → cholesterol ↑ → heart disease, atherosclerosis
Vitamins & Minerals 维生素与矿物质
Vitamin A: vision, epithelial health; deficiency → night blindness 夜盲症
Vitamin C: wound healing, immunity; deficiency → scurvy 坏血病
Vitamin D: calcium absorption; deficiency → rickets 佝偻病
Iron: needed for haemoglobin synthesis 缺铁→贫血
Calcium: bone and teeth health 骨骼牙齿健康
Iodine: needed for thyroid hormone production 缺碘→甲状腺肿大
Water & Fibre 水与纤维
Water makes up 60–70% body weight; essential for: transport, excretion, reactions, temperature regulation
Fibre adds bulk to stool, stimulates peristalsis, prevents constipation
Food Tests 食物测试
Starch test: iodine → blue-black 碘液呈蓝黑色
Reducing sugar: Benedict’s + heat → brick-red 本氏试剂加热呈砖红色
Protein: Biuret test → purple 双缩脲试剂呈紫色
Lipids: ethanol + water → milky emulsion 乙醇与水形成乳白色乳状物
Vitamin C: DCPIP → colorless 二氯酚靛酚褪色
Digestion 消化作用
Mechanical digestion: chewing, peristalsis 物理性咀嚼与蠕动
Chemical digestion: enzymes break large molecules into smaller units 酶的化学作用
Mouth: salivary amylase digests starch 唾液淀粉酶
Stomach: pepsin digests proteins under acidic pH 胃蛋白酶+盐酸
Small intestine: digestion completed by pancreatic and intestinal enzymes
Absorption mainly occurs in small intestine villi 小肠绒毛吸收营养
Assimilation 同化作用
Glucose: converted to glycogen in liver/muscles or used in respiration
Amino acids: form body proteins or enzymes
Excess amino acids: deaminated in liver → urea → excreted
Lipids: stored under skin or used in membrane/energy
Balanced Diet & Daily Needs 平衡饮食与营养需求
Balanced diet includes all 7 nutrients in correct proportion
Factors affecting needs: age, gender, activity level, body size, climate
Pregnant/lactating women need more protein, calcium, iron
Malnutrition = too little or too much of nutrient 营养不良 = 养分摄取不均
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