伤口愈合时为什么会发痒？
Why does a healing wound itch?
愈合早期新血管和肉芽组织生长会释放组胺等介质刺激神经末梢，同时干燥结痂牵拉周围皮肤，二者共同造成瘙痒；过度抓挠可能撕裂新生组织。
Early healing grows new vessels and granulation tissue that release histamine and other mediators stimulating nerve endings, while a drying scab tugs the skin—both cause itch; scratching can tear new tissue.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#伤口愈合 #组胺 #瘙痒
为什么有些人喝酒特别容易脸红？
Why do some people flush red very easily after alcohol?
许多人携带 ALDH2 基因突变，乙醛脱氢酶活性低，喝酒后有毒的乙醛蓄积导致面部血管扩张脸红、心悸，且乙醛积累还会升高致癌风险。
Many carry an ALDH2 mutation with low acetaldehyde dehydrogenase activity, so toxic acetaldehyde builds up after drinking, dilating facial blood vessels (flush) and raising cancer risk.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#酒精 #乙醛 #基因
人的虹膜颜色是由什么决定的？
What determines a person's eye (iris) color?
虹膜颜色主要由基质中黑色素的含量与分布决定：黑色素多呈棕色，少则显蓝色（由胶原对光的散射形成结构色），绿色与黄色脂质也参与。
Iris color mainly depends on melanin amount and distribution in the stroma: more melanin gives brown, less reveals blue from light scattering by collagen (structural color), with yellow lipid also contributing to green.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#虹膜 #黑色素 #结构色
肺泡表面活性物质有什么生理功能？缺乏它会导致什么问题？
What is the physiological function of pulmonary surfactant, and what happens when it is deficient?
表面活性物质由Ⅱ型肺泡细胞分泌，主要成分是二棕榈酰磷脂酰胆碱（DPPC）等磷脂和表面活性蛋白，覆盖在肺泡内表面的液膜上，降低液-气界面的表面张力。呼气时肺泡缩小、表面活性物质相对浓度升高，表面张力进一步降低，防止肺泡塌陷（稳定小肺泡）；吸气时张力升高防止过度扩张，并减少呼吸做功。早产儿肺Ⅱ型细胞尚未成熟、缺乏表面活性物质，导致肺泡塌陷和新生儿呼吸窘迫综合征，可通过气管内补充外源表面活性物质治疗。
Pulmonary surfactant, secreted by type II alveolar cells, consists mainly of phospholipids such as dipalmitoylphosphatidylcholine (DPPC) and surfactant proteins. It lines the liquid film on the alveolar surface and lowers surface tension at the air-liquid interface. During expiration the alveoli shrink, the relative surfactant concentration rises, and surface tension falls further, preventing alveolar collapse and stabilizing small alveoli; during inspiration surface tension rises, preventing over-distension, and the work of breathing is reduced. In premature infants whose type II cells are immature, surfactant deficiency causes alveolar collapse and neonatal respiratory distress syndrome, treated by tracheal instillation of exogenous surfactant.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#肺泡表面活性物质 #Ⅱ型肺泡细胞 #新生儿呼吸窘迫
肾素-血管紧张素-醛固酮系统是如何调节血压和水盐平衡的？
How does the renin-angiotensin-aldosterone system regulate blood pressure and salt-water balance?
血压下降或肾血流减少时，入球小动脉的球旁细胞释放肾素，把肝脏合成的血管紧张素原剪切成血管紧张素I，再由血管紧张素转换酶（ACE）转化为血管紧张素II。血管紧张素II一方面强烈收缩全身小动脉迅速升压，另一方面刺激肾上腺皮质球状带分泌醛固酮，促进远曲小管和集合管重吸收Na+，水随之被重吸收，血容量增加，血压持久升高；它还促进抗利尿激素（ADH）释放，并增强渴觉。该负反馈系统是长期血压调控的核心。
When blood pressure or renal blood flow falls, juxtaglomerular cells of the afferent arteriole release renin, which cleaves liver-derived angiotensinogen into angiotensin I; angiotensin-converting enzyme (ACE) then converts it to angiotensin II. Angiotensin II strongly constricts systemic arterioles, quickly raising pressure, and stimulates the zona glomerulosa of the adrenal cortex to secrete aldosterone, which promotes Na+ reabsorption in the distal tubule and collecting duct; water follows, so blood volume and pressure rise persistently. Angiotensin II also promotes antidiuretic hormone (ADH) release and enhances thirst. This negative-feedback system is central to long-term blood pressure regulation.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#肾素-血管紧张素系统 #醛固酮 #血压调节
人的舌头真有专门的甜、咸、酸、苦、鲜五个味觉区吗？
Does the tongue really have separate regions for sweet, salty, sour, bitter and umami?
传统味觉地图并不准确：舌面各区域都能感知全部五种基本味觉，只是灵敏度略有差异；味觉由味蕾中 G 蛋白偶联受体介导，鲜味由谷氨酸受体识别。
The classic taste map is inaccurate: all tongue regions detect all five basic tastes with only slight sensitivity differences; taste is mediated by G-protein-coupled receptors in taste buds, with umami sensed by glutamate receptors.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#味觉 #味蕾 #鲜味
什么是表型与基因型？
What are phenotype and genotype?
基因型是一个人的遗传信息本身，即DNA上携带的基因组合。表型是可观察到的特征，如身高、血型，由基因型与环境共同决定。同卵双胞胎基因型相同，但表型仍可能因环境而略有差异。
Genotype is a person's actual genetic information, the combination of genes carried in DNA. Phenotype is the observable trait, such as height or blood type, shaped by both genotype and environment. Identical twins share a genotype yet may differ slightly in phenotype due to environment.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#表型 #基因型 #遗传
什么是自身免疫性疾病？
What is an autoimmune disease?
自身免疫性疾病是免疫系统误把自身组织当作外来敌人攻击而导致的疾病。类风湿关节炎、1型糖尿病和红斑狼疮都属于此类。其成因常与遗传、感染和环境因素交织有关。
An autoimmune disease occurs when the immune system mistakenly attacks the body's own tissues as if they were foreign. Rheumatoid arthritis, type 1 diabetes, and lupus are examples. Causes usually involve a mix of genetic, infectious, and environmental factors.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#自身免疫 #免疫 #疾病
为什么生病时体温会升高？发烧到底是帮身体还是害身体？
Why does body temperature rise during illness, and does fever help or harm the body?
病原体感染后，免疫细胞（如巨噬细胞）释放白细胞介素-1 等致热因子，它们作用于下丘脑的体温调节中枢，把“设定温度”调高，身体于是通过肌肉颤抖产热、皮肤血管收缩减少散热，体温升到新标准。中度发热能抑制部分病原体繁殖、加快免疫细胞活化和抗体生成，总体上利大于弊。但体温过高（如超过39℃）会损伤细胞和器官，对幼儿还可能导致热性惊厥，所以高热仍需积极降温。
After infection, immune cells such as macrophages release pyrogens like interleukin-1, which act on the hypothalamus's thermostat and raise the set point. The body then shivers to produce heat and constricts skin vessels to save it, climbing to the new target. A moderate fever slows some pathogens and speeds up immune activation and antibody production, so on balance it helps; but very high temperatures, above about 39 degrees Celsius, damage cells and organs and can trigger febrile seizures in young children, which is why high fever still needs active treatment.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#发热 #下丘脑 #致热因子
春天一到很多人总犯困、提不起精神（“春困”），这真的和光照变化有关吗？
In spring many feel sleepy and sluggish (“spring fatigue”)—does it really link to changing light?
有关。冬去春来白昼变长，光照影响大脑松果体分泌褪黑素，加上气温回暖代谢加快、血管扩张，人会一时调节不过来而犯困。这是身体随季节重新校准的生物钟反应。
Yes. Lengthening spring days change light input to the brain's pineal gland, altering melatonin; warmer weather speeds metabolism and dilates vessels, so the body lags while recalibrating its clock—hence drowsiness.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#春困 #褪黑素 #光照
指纹有什么用，为什么每个人的指纹都不相同？
What are fingerprints for, and why is everyone's different?
指纹的嵴线能增加指尖摩擦力和触觉灵敏度；其在胎儿期由真皮乳头层的随机发育形成，受基因和宫内微环境共同影响，因此高度独特，连同卵双胞胎也不同。
Fingerprint ridges improve grip and tactile sensitivity; they form by random development of the dermal papillae in the womb under both genetic and intrauterine influences, making them highly unique even in identical twins.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#指纹 #皮纹 #身份
精子发生和卵子发生过程有哪些主要差别？
What are the main differences between spermatogenesis and oogenesis?
精子发生在睾丸生精小管中进行，一个精原细胞经减数分裂形成4个等大、带鞭毛的精子，且从青春期起终生不断进行。卵子发生在卵巢中，一个卵原细胞经减数分裂只形成1个富含细胞质和营养的大卵细胞，其余细胞质被分配到3个极体中并退化；卵子的形成在胎儿期即已启动，出生后暂停于减数分裂I，排卵时卵母细胞停留在减数分裂II中期，受精时才完成第二次减数分裂。二者在时间、数量和产物大小上差异显著。
Spermatogenesis occurs in the seminiferous tubules of the testis: one spermatogonium undergoes meiosis to produce four equal-sized, flagellated sperm, and it continues continuously from puberty throughout life. Oogenesis occurs in the ovary: one oogonium yields a single large, cytoplasm-rich ovum, with the rest of the cytoplasm parceled into three polar bodies that degenerate. Oocyte formation begins in fetal life, arrests in prophase of meiosis I, resumes at puberty, and the secondary oocyte is again arrested at metaphase of meiosis II at ovulation; meiosis II is completed only after fertilization. The two processes differ greatly in timing, yield, and cell size.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#精子发生 #卵子发生 #减数分裂
为什么蚊子叮过的地方会鼓起一个又红又痒的小包？
Why does a mosquito bite leave a red, itchy lump?
痒和肿不是蚊子本身造成，而是你的免疫系统在“迎战”。蚊子吸血时注入的唾液含有防止血液凝固的物质，对大多数人来说这些蛋白是过敏原。免疫细胞识别后释放组胺，组胺让局部血管扩张、毛细血管通透性增加，液体渗出到组织里，就形成红、肿、痒的丘疹。再次被叮时反应常更快更重，说明免疫系统已经记住了它。
The itch and swelling are not caused by the mosquito itself but by your immune system fighting back. When it feeds, the mosquito injects saliva containing anticoagulants, and for most people those proteins act as allergens. Immune cells release histamine, which dilates local blood vessels and makes capillaries leaky; fluid seeps into the tissue, producing the red, swollen, itchy wheal. Subsequent bites usually react faster and harder, a sign the immune system remembers the intruder.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#蚊虫叮咬 #组胺 #过敏反应
淋巴系统在维持体液平衡中起什么作用？
What role does the lymphatic system play in maintaining fluid balance?
血液流经毛细血管时，动脉端滤出的液体大部分在静脉端被重吸收，剩余约10%进入毛细淋巴管成为淋巴。淋巴沿淋巴管单向回流，最终经胸导管和右淋巴导管汇入锁骨下静脉回到血液循环，从而维持组织液生成与回流的动态平衡，防止水肿。淋巴管还负责运输肠道吸收的脂肪（乳糜）和免疫细胞。
When blood passes through capillaries, most of the fluid filtered at the arterial end is reabsorbed at the venous end, while the remaining ~10% enters lymphatic capillaries to become lymph. Lymph flows one way through lymphatic vessels and finally returns to the bloodstream via the thoracic duct and right lymphatic duct into the subclavian veins, maintaining a dynamic balance between tissue-fluid production and reabsorption and preventing edema. Lymphatics also transport dietary fats (chyle) from the gut and circulate immune cells.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
《普通生物学》(陈阅增) 循环与淋巴章节
General Biology (Chen Yuezeng), circulatory and lymphatic systems
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787040583151（豆瓣书目条目: 陈阅增普通生物学）
#淋巴系统 #组织液 #体液平衡
疫苗是怎样起作用的？
How do vaccines work?
疫苗把弱化或无害的病原体成分引入体内，训练免疫系统提前识别并记住它。当真正的病原体来袭时，身体能更快更强地反应。这是预防传染病最有效的方法之一。
Vaccines introduce weakened or harmless parts of a pathogen to train the immune system to recognize and remember it. When the real pathogen arrives, the body responds faster and stronger. It is among the most effective ways to prevent infectious disease.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#疫苗 #免疫记忆 #预防
交感神经和副交感神经的作用有何不同？
How do the sympathetic and parasympathetic divisions of the autonomic nervous system differ in their effects?
交感神经在应激、战斗或逃跑时占优势：心率加快、血压升高、支气管扩张、瞳孔放大、胃肠活动受抑；副交感神经在安静休息与消化时主导：心率减慢、血压下降、消化和排空增强。多数内脏器官受两者双重支配且作用相反，共同精细调节内环境。两条通路节前纤维都释放乙酰胆碱；交感节后纤维主要释放去甲肾上腺素，副交感节后纤维仍释放乙酰胆碱。
The sympathetic division dominates in stress, the fight-or-flight response: heart rate and blood pressure rise, bronchi dilate, pupils widen, and gut activity is suppressed. The parasympathetic division prevails at rest, the rest-and-digest state: heart rate slows, blood pressure falls, and digestion is enhanced. Most viscera receive dual, opposing innervation that fine-tunes the internal environment. Both divisions use acetylcholine at the ganglionic synapse; sympathetic postganglionic fibers mainly release norepinephrine, while parasympathetic postganglionic fibers release acetylcholine.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#自主神经 #交感神经 #副交感神经
胃在消化食物中主要发挥哪些作用？
What are the main digestive functions of the stomach?
胃黏膜分泌胃液，含胃酸（盐酸）、胃蛋白酶原和内因子。胃酸为胃蛋白酶提供最适酸性环境（pH约1.5-2），激活胃蛋白酶原并杀灭随食物进入的细菌；胃蛋白酶初步把蛋白质分解成多肽。胃壁平滑肌蠕动将食物与胃液混匀研磨成食糜，再通过幽门间歇排入十二指肠。胃一般不吸收大分子营养，只少量吸收水和酒精。
The gastric mucosa secretes gastric juice containing hydrochloric acid, pepsinogen, and intrinsic factor. The acid creates the optimal acidic environment (pH about 1.5-2) for pepsin, activates pepsinogen, and kills bacteria ingested with food; pepsin begins digesting proteins into polypeptides. Contractions of the stomach wall mix and grind food with gastric juice into chyme, which is delivered intermittently to the duodenum through the pylorus. The stomach normally absorbs little besides water and alcohol.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
《普通生物学》(陈阅增) 消化系统
General Biology (Chen Yuezeng), digestive system
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787040583151（豆瓣书目条目: 陈阅增普通生物学）
#胃 #胃酸 #胃蛋白酶
人睡觉时打鼾是因为什么？
What causes snoring during sleep?
睡眠时咽部软组织松弛，气流通过狭窄气道引起振动发声；肥胖、仰卧、疲劳和饮酒会加重，严重时可伴睡眠呼吸暂停，需就医评估。
During sleep the throat's soft tissues relax and airflow through the narrowed airway vibrates them; obesity, back-sleeping, fatigue and alcohol worsen it, and severe cases may involve sleep apnea needing medical review.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#打鼾 #呼吸道 #睡眠
脚汗多为什么容易有臭味？
Why does sweaty feet tend to smell bad?
脚部汗腺分泌的汗液本身无味，但皮肤上细菌分解其中的蛋白质和脂肪酸，产生短链脂肪酸和氨，从而散发异味。
Foot sweat is odorless by itself, but skin bacteria break down its proteins and fatty acids into short-chain fatty acids and ammonia, producing the smell.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#脚臭 #汗腺 #细菌
为什么人类婴儿的头相对身体特别大，这给分娩带来什么难题？
Why do human babies have unusually large heads, and what challenge does this create for childbirth?
人类婴儿大脑相对身体比例很大且出生时尚未完全发育，以便通过狭窄的骨盆产道，这被称为"次级早产"策略。女性骨盆既要支撑直立行走又要容纳大脑袋，使人类分娩本就困难，婴儿出生后仍需快速发育大脑。
Human babies have large brains relative to body size and are born relatively immature so they can pass through the narrow pelvis—a strategy called "secondary altriciality." Because the female pelvis must both support upright walking and accommodate a big head, human childbirth is inherently difficult, and brain growth continues rapidly after birth.
难度 进阶 · 适合 小学高段(9-12)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
Rosenberg 与 Trevathan，《人类分娩的演化》，《演化人类学》2002年
Rosenberg & Trevathan, "The evolution of human childbirth," Evolutionary Anthropology (2002)
#人类分娩 #大脑发育 #骨盆 #演化
为什么毛细血管是血液与组织细胞之间物质交换的主要场所？
Why are capillaries the main site of exchange between blood and tissue cells?
毛细血管壁仅由单层内皮细胞构成，管壁最薄、管径细小，且全身毛细血管总横截面积巨大，血液流速显著减慢。氧、葡萄糖、氨基酸等小分子经扩散、滤过等过程快速穿过管壁，二氧化碳和代谢废物反向进入血液，因此它是物质交换效率最高的血管。
The capillary wall is only a single layer of endothelial cells, the thinnest of all vessels. Capillaries are narrow, their combined cross-sectional area is enormous, and blood flow slows dramatically in them. Small molecules such as oxygen, glucose, and amino acids diffuse or filter rapidly across the wall, while carbon dioxide and metabolic wastes enter the blood in the opposite direction, making capillaries the most efficient site of exchange.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#毛细血管 #物质交换 #内皮
唾液除了湿润口腔，还有什么重要作用？
Besides moistening the mouth, what important roles does saliva play?
唾液中的淀粉酶已开始分解淀粉，溶菌酶能抑制细菌，它还能帮助味觉、吞咽，并含钙磷帮助牙釉质再矿化。
Saliva's amylase begins starch digestion, lysozyme suppresses bacteria, and it aids taste, swallowing and remineralizes enamel with calcium and phosphate.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#唾液 #淀粉酶 #消化
人为什么会发烧？
Why do people get a fever?
发烧是免疫系统对抗感染时主动调高体温的防御反应，常由病原体刺激产生的物质作用于下丘脑引起。略高的体温能抑制部分微生物并增强免疫细胞活性。但过高或持续不退的发烧需要就医。
A fever is the immune system's defensive move to raise body temperature during infection, often triggered when substances from pathogens act on the hypothalamus. The slightly higher heat can slow some microbes and boost immune cells. But a very high or persistent fever needs medical care.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#发烧 #免疫 #下丘脑
人的头发颜色为什么有黑、棕、金、红之分？
Why do people have black, brown, blond or red hair?
头发颜色由毛囊黑色素细胞产生的真黑素和褐黑素的比例决定，受 MC1R 等基因调控；随着年龄增长黑色素细胞减少，头发就会变白。
Hair color depends on the ratio of eumelanin to pheomelanin made by follicular melanocytes, controlled by genes such as MC1R; as melanocytes decline with age, hair turns gray.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#头发 #黑色素 #基因
为什么憋气时间再长，最后也一定会忍不住大口喘气？
No matter how long you hold your breath, why do you inevitably gasp for air?
憋不住主要是二氧化碳在“报警”，而不是氧气不够。憋气时血中二氧化碳浓度升高、pH 下降，脑干呼吸中枢里的化学感受器立刻被激活，强制发出吸气指令，即使我们主观上还想继续憋。训练有素者能通过降低代谢和耐受高二氧化碳把憋气时间延长到数分钟，但信号机制是一样的。
What forces you to breathe is mostly rising carbon dioxide, not a lack of oxygen. While you hold your breath, CO2 in the blood climbs and pH falls, chemoreceptors in the brainstem breathing centers fire and send an overriding command to inhale, even against your will. Trained breath-holders extend the time by lowering metabolism and tolerating high CO2, but the signaling mechanism is the same.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#憋气 #呼吸中枢 #二氧化碳
晒太阳后皮肤为什么会变黑，黑色素起什么作用？
Why does skin tan after sun exposure, and what role does melanin play?
紫外线刺激皮肤基底层的黑素细胞制造更多黑素，后者被送往表皮细胞，像"小伞"一样吸收并散射UV，保护DNA免受损伤。肤色差异主要由黑素的类型与数量决定，晒黑是身体对紫外线的短期防御反应。
Ultraviolet light stimulates melanocytes in the skin's basal layer to make more melanin, which is delivered to skin cells and acts like a "little umbrella" that absorbs and scatters UV to shield DNA from damage. Skin color mainly reflects the type and amount of melanin, and tanning is the body's short-term defense against UV.
难度 进阶 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Marieb 与 Hoehn，《人体解剖生理学》（第11版，Pearson，2018）
Marieb & Hoehn, Human Anatomy & Physiology (11th ed., Pearson, 2018)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-13-476023-0 (11th ed., Pearson)
#黑色素 #晒黑 #紫外线防护 #黑素细胞
为什么要睡觉？
Why do we need to sleep?
睡眠时大脑整理记忆、清除代谢废物，身体则修复组织和恢复精力。长期缺觉会损害注意力、免疫和情绪。多数成年人每天需要7到9小时睡眠。
During sleep the brain sorts memories and clears metabolic waste, while the body repairs tissue and restores energy. Long-term sleep loss harms attention, immunity, and mood. Most adults need seven to nine hours per night.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#睡眠 #修复 #记忆
为什么剧烈运动后第二天，肌肉会又酸又痛？
Why do muscles ache the day after intense exercise?
酸痛分两种。运动中缺氧时糖被无氧分解产生乳酸，它会随血流很快被清除，所以“运动完立刻的酸”不久就消散。运动后一到三天出现的延迟性肌肉酸痛（DOMS），主要是高强度运动造成的肌纤维微小损伤和随之而来的炎症反应，肌肉肿胀刺激神经末梢产生痛感。这是身体在修复和增强肌肉，循序渐进锻炼能减少它。
There are two kinds. During exercise without enough oxygen, muscle cells break down glucose anaerobically into lactic acid, but the blood clears it quickly, so the burn right after a workout fades soon. The soreness that peaks one to three days later, delayed onset muscle soreness (DOMS), mainly comes from tiny tears in muscle fibers caused by intense work and the inflammation that follows; swollen tissue irritates nerve endings. It is the body repairing and strengthening muscle, and it shrinks with gradual training.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Khan Academy（肌肉代谢）
Khan Academy (muscle metabolism)
#乳酸 #延迟性肌肉酸痛 #肌纤维
人为什么会起鸡皮疙瘩？
Why do we get goosebumps?
寒冷或紧张时交感神经让立毛肌收缩，使汗毛竖起、皮肤出现小凸起；这是多毛祖先竖毛保暖和显大的遗留反应，人类体毛少所以只剩小疙瘩。
In cold or stress, the sympathetic nervous system contracts arrector pili muscles, raising hairs and bumps; this is a vestige of furred ancestors fluffing fur for warmth or intimidation, now just visible as goosebumps.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#鸡皮疙瘩 #立毛肌 #应激
为什么紧张或害怕时会手心出汗、手心发凉？
Why do palms sweat and feel cold when we are nervous or afraid?
这是交感-肾上腺系统的战斗或逃跑反应：肾上腺素使手心和腋下小汗腺活跃出汗，同时皮肤血管收缩把血液调往肌肉和心脏，所以手部又湿又凉。
This is the sympathetic-adrenal fight-or-flight response: adrenaline activates palm and armpit sweat glands while skin blood vessels constrict to shunt blood to muscles and heart, leaving hands damp and cool.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#出汗 #交感 #应激
伤口快好时长痂、底下还发痒，这是在长新肉吗？
As a wound heals it scabs and itches underneath—is new flesh growing?
是的。结痂保护伤口，底下新生的血管和结缔组织在生长，组胺等会刺激神经引起痒感；新神经末梢敏感，所以痒常代表修复在进行，但别抓破痂。
Yes. The scab protects while new vessels and tissue grow underneath; histamine and new, sensitive nerve endings trigger itch. Itch often signals repair—but don't pick the scab.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#伤口 #结痂 #修复
胰腺有什么功能？
What does the pancreas do?
胰腺既是外分泌腺也是内分泌腺：它分泌消化酶进入小肠帮助分解食物，又分泌胰岛素和胰高血糖素调节血糖。若胰岛素不足就会引发糖尿病。
The pancreas is both an exocrine and endocrine gland: it secretes digestive enzymes into the small intestine to break down food and releases insulin and glucagon to regulate blood sugar. Too little insulin leads to diabetes.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#胰腺 #胰岛素 #消化
耳屎（耵聍）是脏东西吗，它有什么作用？
Is earwax (cerumen) just dirt, and what does it do?
耵聍是外耳道腺体的正常分泌物，能黏附灰尘、抑制细菌真菌并润滑耳道；它大多会随咀嚼自行排出，不必频繁掏挖。
Cerumen is a normal secretion that traps dust, inhibits bacteria and fungi and lubricates the canal; it usually clears itself with jaw movement, so frequent picking is unnecessary.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#耳屎 #耵聍 #保护
心脏在身体里是做什么的？
What does your heart do inside your body?
心脏像一台小水泵，不停地把血液送到全身。血液带着氧气和营养，让你有力气活动。
Your heart is like a small pump that sends blood all through your body. The blood carries oxygen and food so you have energy to move.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#心脏 #血液 #人体
我们的眼睛是怎么看见东西的？
How do our eyes let us see?
眼睛像小照相机，光线进到眼里落在视网膜上。眼睛再把画面送到大脑，我们就看见了。
Your eye works like a tiny camera: light comes in and lands on the back of the eye. The eye then sends the picture to your brain, and you see it.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#眼睛 #看见 #人体
血液在身体里有什么用？
What is blood for in our body?
血液像送货的小火车，把氧气和营养送到每个地方。它还会把身体里的垃圾带走。
Blood is like a delivery train that carries oxygen and food everywhere. It also carries away waste so your body stays clean.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#血液 #氧气 #人体
眼睫毛和眉毛除了好看还有什么用？
Besides looking nice, what are eyelashes and eyebrows for?
睫毛像小帘子挡住灰尘和强光，眉毛把额头流下的汗水和雨水引向两侧，防止流进眼睛刺激角膜。
Eyelashes act like a curtain blocking dust and glare, while eyebrows channel sweat and rain from the forehead sideways to keep it out of the eyes.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#睫毛 #眉毛 #保护
我们为什么要打哈欠？
Why do we yawn?
打哈欠会张大嘴深深吸一口气，再慢慢呼出来。虽然确切原因仍有争议，但它可能与给大脑降温、在困倦或无聊时提高警觉有关，而且打哈欠会"传染"——看到别人打也会跟着打。
Yawning is a deep inhale with a wide-open mouth followed by a slow exhale. Its exact cause is still debated, but it may help cool the brain and boost alertness when we are tired or bored, and it is contagious—seeing someone yawn can make us yawn too.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 来源待核验 · Source pending review结论有争议 · Contested
来源 · Source
出处备注：作者 / 书名 / 版次 / 出版社 / 年份齐备，仅缺独立比对证据；已在可信度报告单列披露，不再重复核验。
Provine，《好奇的行为》（普林斯顿大学出版社，2012）
Provine, Curious Behavior (Princeton University Press, 2012)
#打哈欠 #大脑降温 #传染
牙齿由什么组成？
What are teeth made of?
牙齿最外层是坚硬的牙釉质，是人体最硬的组织。里面是牙本质，中心是含神经和血管的牙髓。良好的清洁能保护牙釉质、预防蛀牙。
The outer layer of a tooth is hard enamel, the toughest tissue in the human body. Beneath it lies dentin, and at the center is the pulp with nerves and blood vessels. Good cleaning protects enamel and prevents cavities.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#牙齿 #牙釉质 #口腔
牙膏里常含氟，它对牙齿到底做了什么？
Toothpaste often contains fluoride; what does it do to teeth?
氟能取代牙釉质中羟基磷灰石的羟基，形成更耐酸的氟磷灰石，并抑制致龋菌代谢产酸，从而帮助预防蛀牙。
Fluoride replaces hydroxyl groups in enamel hydroxyapatite to form more acid-resistant fluorapatite and inhibits acid production by cariogenic bacteria, helping prevent cavities.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
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《口腔预防医学》
Dental Caries: The Disease and Its Clinical Management
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787117056274（豆瓣书目条目: 口腔预防医学）
#氟 #牙齿 #防蛀
我们为什么会长牙齿？
Why do we have teeth?
牙齿帮我们把食物咬碎磨细，才好吞下去消化。有了牙齿，吃苹果啃骨头都不难。
Teeth help you bite and chew food into small pieces so it is easy to swallow. With teeth, eating apples or meat is much easier.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#牙齿 #咀嚼 #人体
我们的耳朵是怎么听到声音的？
How do our ears help us hear?
声音像小波浪钻进耳朵，让里面的鼓膜轻轻振动。耳朵把振动变成信号送给大脑，我们就听到了。
Sound travels in waves into your ear and makes a tiny drum inside vibrate. Your ear turns the vibration into a message for the brain, and you hear it.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#耳朵 #听觉 #人体
我们身体里为什么有骨头？
Why do we have bones inside our body?
骨头像小支架，撑起我们的身体让我们能站能跑。骨头还保护着里面软软的器官。
Bones are like a frame that holds your body up so you can stand and run. They also protect the soft parts inside you.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#骨头 #身体 #人体
为什么长时间低头看手机会脖子酸？
Why does looking down at a phone for long make the neck sore?
头部重约 4–5 千克，低头角度越大，颈部肌肉和韧带承受的拉力成倍增加，长期维持姿势就会导致劳损和酸痛。
The head weighs about 4–5 kg, and the greater the downward angle, the more the neck muscles and ligaments are pulled, so holding the posture leads to strain and soreness.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#颈椎 #姿势 #劳损
人的身体里一共有多少块骨头？
How many bones are there in the human body?
小朋友刚出生时骨头比大人还多，大约有300块。长大以后有些长在一起，成年人大约有206块。
A newborn baby has about 300 bones, even more than an adult. As you grow, some bones join together, leaving about 206 in a grown-up.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#骨头 #数量 #人体
切洋葱时为什么会流眼泪？
Why do we cry when cutting onions?
洋葱细胞破损后，蒜氨酸酶把前体物质转化为丙硫醛-S-氧化物（催泪因子），它挥发到空气中刺激角膜神经，引发流泪以冲洗刺激物。
When onion cells are damaged, alliinase converts precursors into syn-propanethial-S-oxide (the lachrymatory factor), which volatilizes and irritates corneal nerves, triggering tears to flush the irritant.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#洋葱 #催泪因子 #酶
人为什么会打喷嚏？
Why do people sneeze?
打喷嚏是鼻子受到灰尘、花粉或病菌刺激时，身体用力把异物排出呼吸道的反应。一股气流能以很高速度冲出鼻腔，带走刺激物。这也是感冒和过敏常见的症状。
A sneeze is the body's forceful ejection of irritants like dust, pollen, or germs from the airways when the nose is stimulated. A burst of air shoots out of the nose at high speed, carrying the irritant away. It is also a common symptom of colds and allergies.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#打喷嚏 #鼻腔 #防御
跑步时为什么心跳会加快？
Why does your heartbeat speed up when you run?
运动时肌肉需要更多氧气，心脏就跳得更快更用力，把更多血液送出去。休息一会儿，心跳会慢慢回到平常。
When you exercise, your muscles need more oxygen, so the heart beats faster and harder to send more blood. After resting, the heartbeat slowly returns to normal.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#心脏 #运动 #人体
指甲是由什么构成的，为什么会不断长长？
What are fingernails made of, and why do they keep growing?
指甲主要由角蛋白构成，由甲根处的甲母质细胞分裂产生并向远端推进，类似头发的生长方式，因此会持续变长。
Nails are mainly keratin, produced by cell division in the nail matrix at the root and pushed outward, much like hair growth, so they keep lengthening.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#指甲 #角蛋白 #生长
我们吃下去的食物去了哪里？
Where does the food we eat go?
食物从嘴巴进入肚子，被肠胃慢慢磨碎变成营养。身体吸收营养后，剩下的变成便便排出去。
Food goes from your mouth into your tummy, where it is broken into tiny bits of goodness. Your body keeps the good parts and sends the rest out as poop.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#消化 #肠胃 #人体
小朋友为什么会越长越高？
Why do children grow taller?
小朋友骨头之间的软软部分会慢慢变长，人就会长高。睡觉和吃好饭能帮助身体长大。
The soft parts between a child's bones slowly stretch longer, so the body grows taller. Sleeping well and eating good food help you grow.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#长高 #骨骼 #人体
皮肤除了保护还有什么功能？
Besides protection, what does skin do?
皮肤是防水屏障，能调节体温（出汗、血流）、感知触觉温度，并合成维生素D，是重要的免疫与感觉器官。
Skin is a waterproof barrier that regulates temperature (sweat, blood flow), senses touch and heat, and makes vitamin D—an important immune and sensory organ.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#皮肤 #屏障 #体温
肝脏有什么作用？
What does the liver do?
肝脏是人体最大的内脏器官，负责解毒、储存糖原和制造胆汁帮助消化脂肪。它还能合成许多重要蛋白质。肝脏有很强的再生能力。
The liver is the body's largest internal organ, handling detoxification, storing glycogen, and making bile to digest fats. It also synthesizes many vital proteins. The liver has a strong capacity to regenerate.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#肝脏 #解毒 #代谢
我们为什么会打嗝？
Why do we get hiccups?
打嗝是因为膈肌突然抽动，让空气猛地进到肺里。喝口水或憋一下气，常常能让它停下来。
A hiccup happens when the muscle under your lungs twitches and air pops into your lungs. A sip of water or holding your breath often stops it.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#打嗝 #膈肌 #人体