📚 Hormones: ADH, Adrenaline, Insulin, Testosterone, Progesterone & Oestrogen | 激素：抗利尿激素、肾上腺素、胰岛素、睾酮、孕激素和雌激素
Hormones are chemical messengers produced by endocrine glands and transported in the blood to target organs, where they bring about specific responses. In the Edexcel IGCSE Biology syllabus (specification point 2.98), you are required to understand the sources, roles and effects of six key hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. This article explains each hormone's origin, function and physiological impact, linking them to homeostasis, reproduction and the 'fight-or-flight' response. By the end, you will be able to describe how these hormones coordinate complex processes in the human body and why their balance is essential for health.
激素是由内分泌腺产生的化学信使，通过血液运输至靶器官，从而引发特定反应。在 Edexcel IGCSE 生物学大纲（考点 2.98）中，要求掌握六种关键激素的来源、作用及效应：抗利尿激素（ADH）、肾上腺素、胰岛素、睾酮、孕激素和雌激素。本文阐释每种激素的生成部位、功能及其生理影响，并将它们与稳态、生殖和“战或逃”反应联系起来。学完本文，你将能够描述这些激素如何协调人体内的复杂过程，以及为何激素平衡对健康至关重要。
1. What Are Hormones? | 什么是激素？
Hormones are organic molecules, typically proteins or steroids, secreted directly into the bloodstream by ductless endocrine glands. Unlike nervous impulses, which are fast and short-lived, hormonal signals are slower but longer-lasting. A hormone will only affect cells that possess complementary receptor proteins on their surface; these are called target cells. After binding, the hormone triggers a cascade of cellular events, altering the activity of the target tissue. The six hormones required for Edexcel IGCSE each play distinct roles in regulation, metabolism and development.
激素是由无导管的内分泌腺直接分泌入血的有机分子，通常为蛋白质或类固醇。与快速而短暂的神经冲动不同，激素信号传导较慢，但作用更持久。激素只作用于表面具有互补受体蛋白的细胞，这些细胞称为靶细胞。激素结合后，会触发一系列细胞活动，从而改变靶组织的活性。Edexcel IGCSE 要求的六种激素各自在调节、新陈代谢和发育中发挥独特作用。
2. Source and Role of ADH | 抗利尿激素的来源与作用
Antidiuretic hormone (ADH), also called vasopressin, is produced in the hypothalamus and released from the posterior pituitary gland. Its primary target is the collecting ducts of the kidneys. ADH increases the permeability of the collecting duct walls to water, allowing more water to be reabsorbed into the blood. This reduces urine volume and concentrates the urine, helping to conserve body water. The release of ADH is regulated by the water potential of the blood; osmoreceptors in the hypothalamus detect changes and trigger negative feedback.
抗利尿激素（ADH），也称血管加压素，由下丘脑产生并由垂体后叶释放。其主要靶标是肾脏的集合管。ADH 增加集合管壁对水的通透性，使更多水分被重吸收回血液。这样会减少尿量、浓缩尿液，有助于保存体内水分。ADH 的释放受血液水势调节；下丘脑中的渗透压感受器检测到变化并触发负反馈。
3. Effects of ADH Imbalance | 抗利尿激素失衡的影响
If ADH secretion is too low, the collecting ducts remain impermeable to water, causing large volumes of dilute urine — a condition known as diabetes insipidus. Conversely, excessive ADH release leads to water retention, diluting body fluids and potentially causing hyponatraemia (low sodium concentration). In a healthy individual, negative feedback ensures that ADH is released when the body is dehydrated and inhibited when the blood is too dilute, thus maintaining osmoregulation.
若 ADH 分泌过少，集合管对水保持不通透，会导致大量稀释尿液——这种情况称为尿崩症。相反，ADH 释放过多会引起水潴留，稀释体液并可能导致低钠血症。健康人体内，负反馈确保在身体脱水时释放 ADH，在血液过度稀释时抑制其释放，从而维持渗透调节。
4. Adrenaline: The Fight-or-Flight Hormone | 肾上腺素：战或逃激素
Adrenaline (epinephrine) is secreted from the adrenal medulla, located on top of the kidneys, in response to stress, fear or excitement. It prepares the body for rapid physical action by increasing heart rate, raising blood pressure, dilating air passages in the lungs and boosting blood supply to skeletal muscles. Simultaneously, it stimulates the liver to convert glycogen into glucose, raising blood glucose concentration for increased energy. Pupils dilate and mental alertness improves, all within seconds of release.
肾上腺素在应激、恐惧或兴奋时由位于肾脏上方的肾上腺髓质分泌。它使身体做好迅速行动的准备：加快心率、升高血压、扩张肺部气道并增加骨骼肌的血液供应。同时，它刺激肝脏将糖原转化为葡萄糖，提高血糖浓度以提供更多能量。瞳孔放大、精神警觉性提高，这些变化均在分泌后数秒内发生。
5. Insulin and Blood Glucose Regulation | 胰岛素与血糖调节
Insulin is a peptide hormone produced by the beta cells of the islets of Langerhans in the pancreas. It is released when blood glucose concentration rises above normal, for instance after a carbohydrate-rich meal. Insulin promotes the uptake of glucose by liver and muscle cells, where it is converted into glycogen for storage. It also increases the permeability of cell membranes to glucose and stimulates fat synthesis. As a result, blood glucose levels fall back to the set point, maintaining homeostasis.
胰岛素是一种肽类激素，由胰腺中胰岛的 β 细胞产生。当血糖浓度超过正常值（例如摄入富含碳水化合物的食物后）时，胰岛素被释放。胰岛素促进肝脏和肌细胞摄取葡萄糖，并将其转化为糖原储存起来。它还增加细胞膜对葡萄糖的通透性并刺激脂肪合成。从而血糖水平降回设定值，维持稳态。
6. Insulin Deficiency and Diabetes | 胰岛素缺乏与糖尿病
Failure to produce sufficient insulin, or resistance of target cells to its effects, results in diabetes mellitus. In type 1 diabetes, the body's immune system destroys the beta cells, so little or no insulin is produced; patients require insulin injections. Without insulin, blood glucose remains dangerously high after meals, leading to glucose in the urine, excessive urination and long-term damage to organs. Understanding the role of insulin makes clear why control of blood sugar is a fundamental part of IGCSE Biology.
胰岛素分泌不足或靶细胞对其产生抵抗，会导致糖尿病。1 型糖尿病中，人体免疫系统破坏了 β 细胞，因此几乎不产生胰岛素；患者需要注射胰岛素。没有胰岛素，餐后血糖居高不下，会导致尿糖、多尿以及长期器官损伤。理解胰岛素的作用，就能明白为何血糖控制是 IGCSE 生物学的基础内容。
7. Testosterone: The Male Sex Hormone | 睾酮：男性性激素
Testosterone is the main androgen produced by the testes in males and, in small amounts, by the ovaries in females. Its release is stimulated by luteinising hormone (LH) from the pituitary gland. During puberty, testosterone promotes the development of male secondary sexual characteristics: deepening of the voice, growth of facial and body hair, increased muscle mass and bone density, and the maturation of the sex organs. It also plays a role in sperm production and maintaining libido throughout adult life.
睾酮是主要的雄激素，由男性睾丸和少量由女性卵巢产生。其释放受垂体分泌的黄体生成素（LH）刺激。在青春期，睾酮促进男性第二性征的发育：声音变得低沉、面部和体毛生长、肌肉质量和骨密度增加以及性器官成熟。它还在成年后维持精子生成和性欲中发挥作用。
8. Oestrogen and the Menstrual Cycle | 雌激素与月经周期
Oestrogen is primarily produced by the ovaries, specifically by the developing follicles. It has several key functions: it stimulates the thickening of the uterine lining (endometrium) during the menstrual cycle, promoting repair and growth after menstruation. Oestrogen also triggers the development of female secondary sexual characteristics at puberty, such as breast development, widening of the hips and the start of menstrual cycles. Additionally, a rising oestrogen level causes a surge in LH, which leads to ovulation around day 14 of the cycle.
雌激素主要由卵巢中的发育卵泡产生。它具有几项关键功能：在月经周期中刺激子宫内膜增厚，促进经期后的修复和生长。雌激素还在青春期触发女性第二性征的发育，如乳房发育、髋部变宽以及月经周期启动。此外，雌激素水平升高会引起 LH 激增，从而导致大约在第 14 天排卵。
9. Progesterone: Preparation for Pregnancy | 孕激素：为怀孕做准备
Progesterone is secreted by the corpus luteum in the ovary after ovulation and, if pregnancy occurs, later by the placenta. Its main role is to maintain the thickened endometrium, making it receptive for embryo implantation. Progesterone also inhibits further ovulation and uterine contractions during pregnancy, creating a stable environment for the developing foetus. A drop in progesterone levels towards the end of the menstrual cycle, if fertilisation does not occur, triggers menstruation as the lining breaks down.
孕激素在排卵后由卵巢中的黄体分泌，若发生怀孕，后续由胎盘分泌。其主要作用是维持增厚的子宫内膜，使其适合胚胎着床。孕激素也抑制进一步的排卵和孕期子宫收缩，为发育中的胎儿创造稳定环境。若未受精，月经周期末孕激素水平下降，会导致内膜脱落，引发月经来潮。
10. Comparing Hormonal and Nervous Control | 激素与神经控制的比较
Hormones and nerve impulses both enable communication within the body, but they differ markedly. Nerve impulses are electrical and travel along neurones at very high speed, producing almost instantaneous but short-lived effects. Hormonal messages are chemical, carried by blood, and thus slower to take effect; however, their responses can last for hours or days. For instance, adrenaline acts quickly for a few minutes, whereas insulin adjustments to blood glucose may persist for hours. The two systems often work together: the sympathetic nervous system can trigger adrenaline release, blending fast neural signals and sustained hormonal effects.
激素与神经冲动均实现体内信息传递，但二者差异显著。神经冲动是电信号，沿神经元高速传播，产生几乎瞬时但短暂的效果。激素信息是化学性的，由血液运输，因此起效较慢，但其反应可持续数小时或数天。例如，肾上腺素快速作用数分钟，而胰岛素对血糖的调节可能持续数小时。这两个系统常协同工作：交感神经系统可触发肾上腺素释放，将快速的神经信号与持久的激素效应结合在一起。
11. Hormones and Homeostasis | 激素与稳态
Homeostasis — the maintenance of a constant internal environment — relies heavily on hormonal negative feedback loops. Blood water potential, blood glucose concentration and core body temperature are all regulated through hormones like ADH, insulin and others. In each case, a deviation from the set point is detected by receptors, the endocrine gland responds by altering hormone output, and the resulting effect reverses the change. This ensures that conditions around cells remain optimal for enzyme activity and cellular functions, a core principle tested frequently in IGCSE Biology.
稳态——维持恒定内环境——在很大程度上依赖激素的负反馈回路。血水势、血糖浓度和核心体温均通过 ADH、胰岛素等激素进行调节。每种情况下，偏离设定值的变化被感受器检测到，内分泌腺通过改变激素分泌作出反应，所产生的效应反转这一变化。这确保了细胞周围环境始终适于酶活性和细胞功能，这也是 IGCSE 生物学中常考的核心原理。
12. Summary and Exam Tips | 总结与备考提示
For Edexcel IGCSE Biology, you are expected to recall the gland and specific cell type that produces each hormone, the target organ, the main effects and the consequences of hormone imbalance. Create a table linking ADH (pituitary/kidneys), adrenaline (adrenal medulla/heart, liver), insulin (pancreas/liver, muscles), testosterone (testes/reproductive organs), oestrogen (ovaries/uterus) and progesterone (corpus luteum/uterus). Practice explaining negative feedback clearly and linking hormones to real-life examples, such as the sprinter's adrenaline rush or an insulin pump for diabetics. This will secure full marks on the relevant questions.
对于 Edexcel IGCSE 生物学，你需要记住每种激素的产生腺体和特定细胞类型、靶器官、主要效应以及激素失衡的后果。可以制作一个表格，将 ADH（垂体/肾）、肾上腺素（肾上腺髓质/心脏、肝脏）、胰岛素（胰腺/肝脏、肌肉）、睾酮（睾丸/生殖器官）、雌激素（卵巢/子宫）和孕激素（黄体/子宫）联系起来。练习清楚地解释负反馈，并将激素与生活实例（如短跑运动员的肾上腺素激增或糖尿病患者的胰岛素泵）相结合，这能确保你在相关题目中获得满分。
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