Otot dan motilitas
International Baccalaureate · IB Diploma · Biology · HL Topik 17 3:41 Narasi bahasa Inggris · Subtitle bahasa Inggris + 中文 disematkan langsung
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A sarcomere 肌节 becomes shorter during contraction although its thick and thin filaments keep approximately the same length.
肌节在收缩过程中会变短，但其粗丝和细丝的长度基本保持不变。
Actin and myosin interact in a sliding-filament mechanism.
肌动蛋白和肌球蛋白通过滑动丝机制相互作用。
Calcium permits the interaction through regulatory proteins.
钙离子通过调节蛋白允许这种相互作用发生。
ATP binding and hydrolysis support the cross-bridge cycle.
ATP的结合与水解支撑横桥循环。
Skeletal muscles pull through tendons and work in coordinated groups.
骨骼肌通过肌腱牵拉，并以协调的肌群形式工作。
Sarcomere: The repeating contractile unit between two Z lines.
肌节：两条Z线之间重复的收缩单位。
Cross-bridge: A myosin-actin interaction during the contraction cycle.
横桥：收缩周期中肌球蛋白与肌动蛋白的相互作用。
During shortening, overlap increases.
收缩过程中，重叠区域增加。
The A-band length stays approximately constant while I bands and the H zone become smaller.
A带长度基本保持不变，而I带和H区变小。
Movement at a joint also depends on tendon insertion, lever geometry, and opposing muscle activity.
关节运动还取决于肌腱附着点、杠杆几何结构以及拮抗肌的活动。
In the lab: Annotate two sarcomere diagrams at different lengths using the same scale.
在实验室中，使用相同的比例尺对两个不同长度的肌节图进行标注。
Track band widths separately from filament length.
将带宽与丝长分开记录。
Use prepared models or existing images, not painful or maximal-exertion tasks.
使用现成模型或现有图像，避免疼痛或极限用力任务。
Known: sarcomere length changes from 2.5 to 2.0 micrometres.
已知：肌节长度从2.5微米变为2.0微米。
Percentage shortening equals 2.5 minus 2.0, all over 2.5, times 100, which is 20 percent.
缩短百分比等于2.5减2.0，除以2.5，再乘以100，即20%。
This does not mean either filament shortened by 20 percent.
这并不意味着任一根细丝都缩短了20%。
Your turn: A sarcomere shortens from 3.0 to 2.4 micrometres.
请作答：肌节从 3.0 微米缩短至 2.4 微米。
Calculate percentage shortening.
请计算缩短的百分比。
Pause the video and work it out.
请暂停视频，自己算一算。
Check: 0.6 divided by 3.0 is a shortening of 20 percent.
核对：(3.0 − 2.4) ÷ 3.0，缩短 20%。
ATP is required for myosin detachment as well as the continuing cycle.
肌球蛋白脱离以及持续循环都需要ATP。
A muscle pulling harder does not mean all its fibers become shorter under every load.
肌肉拉力增大，并不意味着所有肌纤维在每种负荷下都会缩短。
Not true: Contracting muscle shortens by shrinking every actin filament.
不正确。 收缩的肌肉并非通过缩短每根肌动蛋白丝而变短。
Contraction is sliding, not shrinking: actin and myosin filaments keep their length while their overlap increases.
收缩是滑动而非缩短：肌动蛋白丝和肌球蛋白丝保持其长度不变，同时它们的重叠部分增加。
A filament that shortened would contradict the sliding-filament evidence.
如果肌动蛋白丝发生缩短，将与滑动丝证据相矛盾。
Actin and myosin interact in a sliding filament mechanism.
肌动蛋白和肌球蛋白通过滑行机制相互作用。
During shortening, overlap increases.
在收缩过程中，重叠区域增加。
Watch for: ATP is required for myosin detachment as well as the continuing cycle.
请注意：ATP不仅用于肌球蛋白的脱离，也是持续循环所必需的。
A sarcomere shortens from 2.0 to 1.5 micrometres.
肌节从2.0微米缩短至1.5微米。
Find the percentage shortening.
请计算缩短的百分比。
The filaments themselves do not shorten by that percentage.
注意，肌丝本身的长度并未按此比例缩短。
The result is a shortening of 25 percent.
结果是缩短25%。
In contraction the actin and myosin filaments keep their length.
收缩时肌动蛋白和肌球蛋白丝的长度不变。
They slide past each other, so the Z-lines move closer and the sarcomere shortens.
它们相互滑动，使Z线靠近，肌节缩短。
A fictional sarcomere shortens from 2.8 to 2.1 micrometres.
一个虚构的肌节从 2.8 缩短至 2.1 微米。
Calculate shortening and explain whether the model requires actin filaments to shorten.
请计算缩短量，并解释该模型是否要求肌动蛋白丝发生缩短。
The sarcomere shortens by 25 percent.
肌节缩短了 25%。
Sliding-filament reasoning changes overlap and sarcomere length, not filament length.
按照肌丝滑行模型，改变的是重叠程度和肌节长度，而不是肌丝本身的长度。
The numerical observation alone does not measure force or diagnose function.
单凭这个数值观察既不能测量力量，也不能诊断功能。
Pause and check yourself. Explain each point on screen in your own words, then change one number in the last example and say which assumption must still hold.
暂停一下，自我检查：用自己的话解释屏幕上的每个要点，再改动最后一个例子中的一个数字，说明哪个假设仍然必须成立。