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Week 10 · Module overview

Week 10 — Muscle Tissue & the Physiology of Contraction

Human Anatomy and Physiology I Free sample edition

Why this matters

A future nurse reading why a body stiffens after death, a physical therapist watching a grip weaken, and a distance runner whose calves outlast a sprinter's all rely on the same order of events inside a muscle fiber.

In plain language

Every move you make, from a blink to a sprint, starts when a muscle pulls. This week you look inside one skeletal muscle and follow a single command from a nerve to the tiny moving parts that do the pulling. You meet the sarcomere (the smallest unit in a muscle that can shorten) and the two kinds of strands inside it that slide past each other. You put the steps of a contraction in their fixed order, and you see why the fuel molecule ATP is needed to let go as well as to pull. You finish by reading a set of grip counts to see what fatigue (a muscle's falling ability to keep contracting) looks like in numbers.

  • Already covered: Week 2 gave you ATP; Week 3, ions and pumps; Week 5, skeletal muscle tissue.
  • This week: the sarcomere, sliding filaments, the five contraction steps, ATP's jobs, and fatigue.
  • How they connect: a muscle fiber is a cell, so membranes, ions, pumps, and ATP all work here.
  • Where we're going next: Week 11, The Muscular System.

Focus

In what exact order does a nerve signal become a sliding filament, and why does a squeeze slow down?

By the end of this module, you should be able to:

  • [ ] label a sarcomere's Z discs, actin, and myosin
  • [ ] put the five steps of contraction in order with their places
  • [ ] name ATP's three jobs, including relaxation
  • [ ] work the average and percent decline of a grip series

To-do

Plan your week

  1. Read Chapter 10 (45 minutes), then the lecture and slides.
  2. Work the tutorial (60–90 minutes) and practice set (20 minutes).
  3. Run the A&P Lab & Inquiry (2 hours), then the discussion and assignment.
  4. Take the quiz.

This week's checkpoint: put the five steps of a contraction in order, from acetylcholine to the power stroke.

You've got this

Take it in order; ask your instructor if a step snags.

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