Sarcomere and contraction
Fri, Feb 19, 2027 · Week 5 · Human Anatomy & Physiology (Human Body Systems)
Today's goal: Describe sarcomere structure and explain contraction using the sliding-filament model.
What a finished product looks like
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Labeled sarcomere (in order across the unit):
- Z-line: the boundary at each end of the sarcomere; thin filaments anchor here.
- I-band: the lighter region containing only thin (actin) filaments, spanning a Z-line.
- A-band: the darker region the length of the thick (myosin) filaments; thin filaments overlap here.
- Actin: the thin filament.
- Myosin: the thick filament with heads that grab actin.
Sliding-filament explanation (two sentences): When a muscle shortens, myosin heads attach to actin and pull the thin filaments toward the center of the sarcomere, so the Z-lines move closer together. The A-band stays the same width while the I-band and H-zone narrow, because the filaments slide past each other rather than shortening themselves.
Also due today: Submit a photo of your dated notebook page.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.