更年期是怎么回事？
What happens during menopause?
更年期是女性卵巢功能衰退、雌激素水平下降导致月经永久停止的阶段。常伴随潮热、情绪波动等症状。它是生殖衰老的自然过程，多发生在45到55岁。
Menopause is the stage when ovarian function declines and estrogen falls, ending menstruation permanently. It often brings hot flashes and mood swings. It is a natural part of reproductive aging, usually around ages 45 to 55.
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)
#更年期 #雌激素 #衰老
形态发生素梯度（morphogen gradient）如何在发育中提供位置信息，以果蝇双胸复合体为例说明？
How do morphogen gradients provide positional information during development, illustrated by the Drosophila Bithorax complex?
形态发生素由局部源扩散形成浓度梯度，细胞依据接收到的浓度阈值激活不同靶基因组合，从而「读出」自身位置。在果蝇中，双胸复合体沿前后轴的表达受这类梯度调控，决定体节身份并塑造躯干蓝图。
A morphogen diffuses from a local source to form a concentration gradient, and cells read their position by the threshold at which they activate different target-gene combinations. In Drosophila, expression of the Bithorax complex along the anterior-posterior axis is governed by such gradients, specifying segment identity and shaping the body plan.
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)
#形态发生素 #位置信息 #双胸复合体 #体节
山中伸弥因子（Oct3/4、Sox2、Klf4、c-Myc）使体细胞重编程为多能状态的分子逻辑是什么？
What is the molecular logic by which the Yamanaka factors (Oct3/4, Sox2, Klf4, c-Myc) reprogram somatic cells to a pluripotent state?
这四个转录因子协同重塑染色质并激活多能性网络核心基因，同时抑制体细胞身份相关程序。它们逐步关闭分化基因、开启 Nanog 等干性基因，最终使表观遗传时钟回拨到类胚胎状态。c-Myc 促进增殖但也是致瘤风险来源。
The four transcription factors cooperatively remodel chromatin and activate the core pluripotency network while repressing somatic identity programs. They progressively silence differentiation genes and turn on stemness genes such as Nanog, rewinding the epigenetic clock toward an embryo-like state. c-Myc boosts proliferation but also contributes tumorigenic risk.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Takahashi, Yamanaka,《Induction of Pluripotent Stem Cells from Mouse Embryonic and Adult Fibroblast Cultures by Defined Factors》,Cell,2006 (DOI: 10.1016/j.cell.2006.07.024)
Takahashi, Yamanaka, 'Induction of Pluripotent Stem Cells from Mouse Embryonic and Adult Fibroblast Cultures by Defined Factors', Cell, 2006, DOI: 10.1016/j.cell.2006.07.024
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.cell.2006.07.024
#山中因子 #重编程 #表观遗传 #多能性网络
端粒与衰老有什么关系？
How are telomeres related to aging?
端粒是染色体末端的保护帽，每次细胞分裂都会缩短一点。当端粒过短，细胞停止分裂进入衰老。端粒长度被视为细胞老化的“生物钟”。
Telomeres are protective caps at chromosome ends that shorten a bit each cell division. When too short, the cell stops dividing and ages. Telomere length is seen as a biological clock of cellular aging.
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)
#端粒 #染色体 #衰老
衰老过程中细胞发生了什么变化？
What changes happen to cells during aging?
衰老细胞停止分裂却持续存在，并分泌促炎物质影响周围。DNA损伤累积、线粒体功能下降，使组织修复变慢。这些过程共同导致机体功能逐渐衰退。
Aging cells stop dividing yet persist, secreting inflammatory substances that affect neighbors. DNA damage accumulates and mitochondrial function declines, slowing tissue repair. Together these drive gradual loss of function.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
López-Otín, Blasco, Partridge, Serrano 等,《The Hallmarks of Aging》,Cell,2013 (DOI: 10.1016/j.cell.2013.05.039)
López-Otín et al., 'The Hallmarks of Aging', Cell, 2013, DOI: 10.1016/j.cell.2013.05.039
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.cell.2013.05.039
#衰老 #细胞 #线粒体
端粒缩短为什么会触发细胞衰老,这一机制对生物体一定是坏事吗?
Why does telomere shortening trigger cellular senescence, and is this mechanism necessarily bad for the organism?
染色体末端重复序列随每次复制逐渐丢失,过短的端粒失去保护性结构后被识别为DNA双链断裂,激活p53-p21通路使细胞永久退出增殖周期。虽然这限制了组织的再生潜力,但它同时是一道防癌屏障,阻止携带潜在突变的细胞无限分裂。在小鼠模型中强行延长端粒酶活性虽改善组织功能,却也提高某些肿瘤的发生率。
Telomeric repeats erode with each round of replication; once critically short, chromosome ends lose their protective structure and are sensed as double-strand breaks, activating the p53-p21 pathway and permanently withdrawing the cell from proliferation. Although this curbs tissue regenerative capacity, it also acts as an anti-cancer barrier against unlimited division of cells carrying latent mutations. Mouse experiments that forcibly extend telomerase activity improve tissue function yet raise the incidence of some tumors.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Bernardes de Jesus & Blasco,《Telomerase at the intersection of cancer and aging》,Trends in Genetics,2013 (DOI: 10.1016/j.tig.2013.06.007)
Bernardes de Jesus & Blasco, 'Telomerase at the intersection of cancer and aging', Trends in Genetics, 2013, DOI: 10.1016/j.tig.2013.06.007
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.tig.2013.06.007
#衰老生物学 #端粒
人的心脏总偏左、肝脏总偏右：胚胎最初对称的身体是如何建立起稳定的左右差异的？
The human heart always ends up on the left and the liver on the right—how does the initially symmetrical embryo establish consistent left-right differences?
关键在胚胎节点的纤毛：它们统一后倾并定向旋转，驱动周围胚外液体形成持续的左向流动。左缘的纤毛感知该信号后启动Nodal级联，使Lefty、Pitx2等基因只在左侧表达，指定心脏环转与内脏定位。驱动蛋白KIF3B为纤毛组装所必需，其突变会让节点纤毛完全缺失、左向流动消失，内脏位置随之镜像反位或随机分布——证明方向性纤毛流本身携带左右轴的原初信息。
The key lies in the cilia of the embryonic node: uniformly tilted posteriorly, they rotate in one direction, driving the surrounding extraembryonic fluid in a steady leftward flow. Cilia on the left rim sense this cue and trigger the Nodal cascade, so genes such as Lefty and Pitx2 switch on only on the left, orienting heart looping and organ placement. The kinesin KIF3B is required to assemble cilia at all; mutating it removes the nodal cilia entirely, abolishing leftward flow and randomizing organ situs—proof that directional ciliary flow itself carries primordial left-right information.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Nonaka S. 等《Randomization of left-right asymmetry due to loss of nodal cilia generating leftward flow of extraembryonic fluid in mice lacking KIF3B motor protein》,Cell,1998年第95卷第829-837页
Nonaka S. et al., "Randomization of left-right asymmetry due to loss of nodal cilia generating leftward flow of extraembryonic fluid in mice lacking KIF3B motor protein," Cell 95:829-837 (1998)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1016/s0092-8674(00)81705-5：Randomization
#左右不对称 #节点纤毛 #Nodal信号 #内脏定位
人体细胞多久更新一次？
How often do human cells renew?
不同细胞更新速度差异很大：肠道上皮几天一换，皮肤约几周，红细胞约120天。而心肌细胞和多数神经元几乎终身不更替。这种差异反映了各组织的功能需求。
Cell renewal rates vary widely: gut lining renews in days, skin in weeks, red cells in about 120 days. Heart muscle cells and most neurons rarely renew in a lifetime. This reflects each tissue's functional needs.
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)
#细胞更新 #组织 #周期
胎儿是如何获得氧气和营养的？
How does a fetus get oxygen and nutrients?
胎儿通过胎盘与母体血液进行物质交换，脐带把富氧血和营养运给胎儿。母体血液与胎儿血液并不直接混合，隔着胎盘薄膜交换。出生后脐带断开，婴儿改用肺呼吸。
The fetus exchanges substances with the mother's blood through the placenta, and the umbilical cord carries oxygen-rich blood and nutrients to it. The two blood supplies do not mix directly, exchanging across the placental membrane. After birth the cord is cut and the baby breathes with lungs.
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)
#胎儿 #胎盘 #脐带
为什么老年人更容易骨折？
Why are older people more prone to fractures?
随着年龄增长，骨量流失、骨密度下降，骨骼变脆，即骨质疏松。肌肉力量减弱也增加跌倒风险。补钙、运动和维生素D有助于延缓。
With age, bone mass and density drop, making bones brittle—osteoporosis. Weaker muscles also raise fall risk. Calcium, exercise, and vitamin D help slow it.
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)
#骨质疏松 #骨密度 #骨折
为什么伤口愈合会随着年龄变慢？
Why do wounds heal more slowly with age?
年长后血液循环减弱、细胞更新变慢，成纤维细胞和免疫细胞效率下降。胶原蛋白合成减少也使修补变缓。因此老人伤口更易感染、恢复更久。
With age, blood flow weakens and cell renewal slows; fibroblasts and immune cells work less efficiently. Reduced collagen synthesis also slows repair. Thus older people's wounds heal slower and risk more infection.
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)
#伤口愈合 #年龄 #胶原
为什么人会长高（青春期）？
Why do people grow taller (during puberty)?
长高依赖长骨两端的生长板不断生成新软骨并骨化。青春期生长激素和性激素大量分泌，加速这一过程。生长板闭合后身高基本定型。
Growth depends on the growth plates at the ends of long bones continuously making new cartilage that turns to bone. In puberty, growth hormone and sex hormones surge and speed this up. Once the plates close, height is largely fixed.
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)
#生长板 #生长激素 #青春期
干细胞为什么具有特殊的研究价值？
Why are stem cells of special research value?
干细胞具有自我更新和分化为多种专门细胞的能力：胚胎干细胞可分化为几乎任何细胞类型，成体干细胞则负责组织修复。它们在再生医学、药物筛选和疾病模型中前景广阔，但也伴随伦理与技术争议。
Stem cells can self-renew and differentiate into specialized cell types: embryonic stem cells can become nearly any cell, while adult stem cells repair tissue. They hold promise for regenerative medicine, drug screening, and disease models, alongside ethical and technical debates.
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)
#干细胞 #分化 #再生医学
胚胎干细胞与诱导多能干细胞（iPSC）在来源和伦理争议上有何不同？
How do embryonic stem cells and induced pluripotent stem cells (iPSCs) differ in origin and ethical debate?
胚胎干细胞取自早期胚胎内细胞团，涉及破坏胚胎的伦理争议；iPSC 则通过向成体体细胞导入少数转录因子重编程而来，来源无创且可来自患者自身。两者都能分化为三胚层细胞，但 iPSC 绕开了胚胎来源的主要伦理障碍。
Embryonic stem cells come from the inner cell mass of early embryos and raise ethical concerns about embryo destruction, whereas iPSCs are reprogrammed from adult somatic cells by introducing a few transcription factors and can be patient-specific. Both differentiate into all three germ layers, but iPSCs avoid the main ethical obstacle of embryo sourcing.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Takahashi, Tanabe, Ohnuki, Narita,《Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors》,Cell,2007 (DOI: 10.1016/j.cell.2007.11.019)
Takahashi, Tanabe, Ohnuki, Narita, 'Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors', Cell, 2007, DOI: 10.1016/j.cell.2007.11.019
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.cell.2007.11.019
#胚胎干细胞 #iPSC #重编程 #伦理
什么是「衰老标志」（hallmarks of aging）框架，它包含哪些主要类别？
What is the hallmarks of aging framework, and what main categories does it include?
该框架把衰老归纳为九到十二项可测量的分子与细胞改变，分为主要标志（如基因组不稳定、端粒损耗）、对抗标志（如线粒体功能障碍）和整合标志（如干细胞耗竭）。它帮助研究者系统定位干预靶点。
The framework organizes aging into nine to twelve measurable molecular and cellular alterations, grouped as primary hallmarks (e.g., genomic instability, telomere attrition), antagonistic hallmarks (e.g., mitochondrial dysfunction) and integrative hallmarks (e.g., stem cell exhaustion). It helps researchers systematically locate intervention targets.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
López-Otín, Blasco, Partridge, Serrano,《The Hallmarks of Aging》,Cell,2013 (DOI: 10.1016/j.cell.2013.05.039)
López-Otín, Blasco, Partridge, Serrano, 'The Hallmarks of Aging', Cell, 2013, DOI: 10.1016/j.cell.2013.05.039
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.cell.2013.05.039
#衰老标志 #基因组不稳定 #线粒体功能障碍 #干细胞耗竭
为什么大多数体细胞不表达端粒酶，而生殖细胞和多数癌细胞却重新激活它？
Why do most somatic cells not express telomerase, whereas germ cells and most cancer cells reactivate it?
端粒酶可在染色体末端添加重复序列以抵消缩短，体细胞中的表达被表观遗传沉默以限制无限增殖、降低癌变风险。生殖细胞需要维持端粒跨代稳定，而癌细胞重激活端粒酶以实现永生，约 85% 的人类肿瘤依赖此机制。
Telomerase adds repeat sequences to chromosome ends to counter shortening; its expression is epigenetically silenced in somatic cells to limit unlimited proliferation and reduce cancer risk. Germ cells need stable telomeres across generations, while cancers reactivate telomerase for immortality, about 85% of human tumors depend on it.
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)
#端粒酶 #永生 #表观沉默 #肿瘤
细胞衰老（senescence）除了停止分裂，还会通过什么方式影响周围组织？
Besides stopping division, how does cellular senescence affect surrounding tissues?
衰老细胞分泌一组促炎、促纤维化的因子，统称衰老相关分泌表型（SASP），可改变微环境并促进慢性炎症。清除衰老细胞在动物模型中能改善多种老年相关疾病，提示 SASP 是衰老病理的重要驱动。
Senescent cells secrete a panel of pro-inflammatory and pro-fibrotic factors known as the senescence-associated secretory phenotype (SASP) that remodels the microenvironment and promotes chronic inflammation. Clearing senescent cells alleviates several age-related diseases in animal models, suggesting SASP is a key driver of aging pathology.
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)
#细胞衰老 #SASP #慢性炎症 #衰老细胞清除
为什么染色体末端会随着每一轮DNA复制而缩短几个核苷酸？
Why does every round of DNA replication shave a few nucleotides off chromosome ends?
前导链可以干净地起始合成，而后随链复制依赖RNA引物，其末端一份被切除后无法补齐，留下无法填补的缺口。端粒重复序列正是吸收这一损失的消耗性缓冲垫。当端粒缩短到临界长度时，依赖p53的检查点会阻止细胞分裂或使其进入衰老状态，这一过程被认为与老年组织的功能衰退相关。
Leading-strand synthesis starts cleanly, but lagging-strand replication depends on RNA primers whose terminal copy cannot be replaced once removed, leaving an unfillable gap. Telomeric repeats absorb this loss, acting as disposable buffers at chromosome tips. Once telomeres become critically short, p53-driven checkpoints halt division or push cells into senescence, a process linked to tissue dysfunction in old age.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Shay, Wright,《Telomeres and telomerase: three decades of progress》,Nature Reviews Genetics,2019 (DOI: 10.1038/s41576-019-0099-1)
Shay, Wright, 'Telomeres and telomerase: three decades of progress', Nature Reviews Genetics, 2019, DOI: 10.1038/s41576-019-0099-1
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1038/s41576-019-0099-1
#端粒缩短 #细胞衰老
鸡胚实验中，将肢芽后缘的极化活性区（ZPA）移植到前缘，为什么会长出前后镜像排列的额外足趾？
In chick embryo grafting experiments, why does transplanting the zone of polarizing activity (ZPA) from the posterior edge of the limb bud to the anterior edge yield extra digits arranged in mirror image?
ZPA是肢芽后缘的一小群信号细胞，持续分泌形态发生素Shh，建立由后向前递减的浓度梯度。各趾前体细胞依据所受Shh浓度与暴露时长解读位置：高强度长时程指定后端趾，弱短信号指定前端趾。前移的ZPA叠加出反向梯度，两组位置指令并存，便形成镜像重复的趾列——由此确立“组织者—梯度”图式建成的经典范式。
The ZPA is a small cluster of signaling cells at the posterior rim of the limb bud that continuously secretes the morphogen Sonic hedgehog, setting up a concentration gradient that decreases from back to front. Precursor cells read their position from both Shh concentration and exposure time: strong, sustained signaling specifies posterior digits, weak brief signaling anterior ones. A grafted ZPA superimposes an opposing gradient, so two sets of positional instructions coexist and a mirror-imaged digit series forms—the classic organizer-and-gradient model of organ patterning.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Riddle R.D. 等《Sonic hedgehog: a family of putative signaling molecules that could specify digit identity》,Cell,1993年第75卷第1401-1416页
Riddle R.D. et al., "Sonic hedgehog: a family of putative signaling molecules that could specify digit identity," Cell 75:1401-1416 (1993)
#形态发生素 #位置信息 #肢体发育
小肠内壁被胃酸和消化液日夜冲刷,为什么几天就能换上一层新的?
The gut lining is scoured by acid and digestive juices daily — how does it renew itself within days?
秘密藏在肠壁上无数个叫隐窝的小凹槽里。每个隐窝底部驻扎着少量 Lgr5 标记的干细胞,它们一边源源不断地分裂,新生成的细胞沿着凹槽向上迁移、分化成吸收细胞和杯状细胞等功能角色,大约3到5天走完从出生到脱落的一生;衰老细胞到达绒毛顶端后凋亡脱落,干细胞补位循环不息。正是这套流水线让小肠顶得住持续的化学磨损,也是它受损后愈合极快的原因。
The secret sits in countless pits called crypts. Each crypt harbors a few Lgr5-marked stem cells at its base that divide continuously; newborn cells stream upward, differentiating into absorptive enterocytes and goblet cells over a lifespan of roughly three to five days before dying at the villus tip and being shed, while stem cells replenish the conveyor. This assembly line lets the intestine withstand constant chemical wear — and explains why it heals so fast after injury.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
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Barker 等,《Identification of stem cells in small intestine and colon by marker gene Lgr5》,Nature 第449卷,2007
N. Barker et al., Identification of stem cells in small intestine and colon by marker gene Lgr5, Nature 449, 2007
独立核验依据 · Independent verification: 核验依据 1 EUROPEPMC 标识 17934449：Identification of stem cells in sm
#干细胞 #肠道隐窝 #组织再生
端粒随细胞分裂逐渐缩短，这一机制与细胞衰老有何关系？
How is the progressive shortening of telomeres with cell division related to cellular senescence?
正常体细胞的端粒因 DNA 复制的「末端复制问题」每次分裂丢失数十至数百碱基。当端粒缩短到临界长度，细胞进入复制性衰老而停止分裂，这是一种抑制肿瘤但也推动组织退化的双重机制。
In normal somatic cells, telomeres lose dozens to hundreds of base pairs per division because of the end-replication problem. Once they shrink below a critical length, cells enter replicative senescence and stop dividing, a double-edged mechanism that suppresses tumors yet drives tissue degeneration.
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)
#端粒 #细胞衰老 #末端复制问题 #复制性衰老
为什么皮肤受伤会结疤？
Why does injured skin form a scar?
较深伤口时，身体用胶原蛋白快速修补，但新生组织纤维排列较乱，不同于原有皮肤。于是形成颜色质地不同的疤痕。浅层损伤只伤及表皮，通常不留疤。
For deeper wounds, the body quickly patches with collagen, but the new fibers are arranged messily, unlike original skin. This leaves a scar of different color and texture. Superficial damage to the epidermis usually leaves no scar.
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)
#疤痕 #胶原蛋白 #伤口愈合
乳牙为什么会被恒牙替换？
Why are baby teeth replaced by permanent teeth?
乳牙较小，适合幼儿较小的颌骨。随着颌骨长大，下方恒牙逐渐发育并顶替乳牙位置。乳牙脱落后恒牙萌出，伴随人一生。这是发育中的正常更替。
Baby teeth are small, suited to a child's smaller jaw. As the jaw grows, permanent teeth develop beneath and push the baby teeth out. After the deciduous teeth fall, the permanent ones emerge for life. This is normal developmental replacement.
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)
#乳牙 #恒牙 #发育