Module 02 — Support and Movement · quiz worth 36 pts · 2026-09-22
Control alone is not enough; combine control, microscopic appearance, and location.
Smooth muscle lacks them; skeletal and cardiac muscle have them.
Long parallel fibers suggest skeletal; branched linked cells suggest cardiac; spindle-shaped cells suggest smooth.
Bone movement is usually skeletal, the heart is cardiac, and hollow-organ walls are smooth.
Which tissue is striated but involuntary and found only in the heart?
Cardiac muscle.
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Skeletal muscle is striated, usually voluntary, and moves bones. Its fibers are long and multinucleated. Cardiac muscle is striated, involuntary, branched, and linked by intercalated discs in the heart. Smooth muscle is nonstriated and involuntary; spindle-shaped cells move materials through hollow organs and adjust tube diameter.
A muscle's origin is the attachment that is relatively fixed during a motion. Its insertion is the attachment that moves toward the origin when the muscle contracts. The names do not mean that one endpoint can never move; they describe the usual action being studied.
Whole muscle contains bundles called fascicles; each fascicle contains muscle fibers, and each fiber contains myofibrils. Connective-tissue coverings organize and support those levels and merge into tendons. Blood vessels deliver oxygen and nutrients, while motor nerves signal the fibers.
The sarcolemma is the muscle fiber's cell membrane. The sarcoplasmic reticulum stores and releases calcium ions used to regulate contraction. Inside myofibrils, repeating sarcomeres contain the actin and myosin filaments that slide in 02.05.
Striations help distinguish skeletal and cardiac muscle from smooth muscle. Branching cells and intercalated discs point to cardiac tissue; long parallel multinucleated fibers point to skeletal tissue; sheets of spindle-shaped cells without striations point to smooth tissue. A biopsy provides a tissue sample, but diagnosis depends on more than a single visual feature.
A strain injures muscle or tendon, while other conditions can damage fibers, nerves, blood supply, or the proteins that support contraction. Compare diseased and healthy tissue with specific evidence—cell shape, organization, damage, and symptoms—without treating a portal image or one clue as a medical diagnosis.
The assigned assessment requires the captured Muscular System Worksheet: identify muscles on the body, then explore how an activity uses them. Use the original worksheet instructions and rubric in the assigned course, complete every section, and upload that work there. The practice below checks concepts; it is not the submission.
Keep concept practice and submitted work separate.
Complete the captured Muscular System Worksheet rather than copying the portal practice.
The local directions require muscle identification and an activity analysis.
Review the actual rubric and upload the finished worksheet there.
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Choose the tissue, attachment term, or muscle component supported by each clue.
Tick these off as you go. Saved in this browser.
