Medoceo
Muscular System
Muscular System Quiz
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1. Which is the largest of the structures in a muscle fibre?
A: A myofibril extends the length of a muscle cell. A myofilament is shorter than a sarcomere, while myosin is a molecule in a thick myofilament.
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2. Which of the following is the smallest structure within a muscle fibre?
A: Myosin is a molecule that makes up a thick myofilament. Many thick and thin myofilaments make up a sarcomere. Many sarcomeres joined end to end form a myofibril.
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3. Which protein(s) are found in thin myofilaments?
C: Actin is the major component of a thin filament. Tropomyosin covers the biding site, while troponin provides the mechanism for removing tropomyosin from the binding site.
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4. By which term is a muscle that opposes or reverses a particular movement called?
C: An agonist muscle performs the action, while the antagonist must relax (be stretched) while the action is being performed (and can reverse the action of the agonist).
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5. What is a “sarcomere”?
C: A myofilament is a long line of sarcomeres joined end to end. So one section of a myofilament is a sarcomere.
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6. All of the following structures are part of a muscle cell except?
A: Sarcoma refers to a malignant tumour (a cancer) of connective or other non-epithelial tissue (bones, muscles, tendons, cartilage, nerves, fat and blood vessels).
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7. Which muscle naming criteria are used to name the quadriceps femoris?
D: Femoris refers to location on the femur; quadriceps refers to four origins.
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8. By what name is something that attaches a bone to another bone known?
C: Ligament is the “ligature” that joins articulating bones. A tendon (or an aponeurosis) attaches a muscle to a bone.
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9. Which of the muscles listed below is named according to its action?
A: Adduction is the action of bringing an abducted bone back towards the body’s midline.
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10. Which statement below best describes the role of Ca++ in muscle contraction?
A: Ca+ attaches to troponin causing a shape change which shifts the attached tropomyosin away from binding sites of actin.
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11. Which term is given to the unit of a myofibril that contracts?
B: The contraction of a myofibril is due to the shortening of its component sarcomeres
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12. Smooth muscle cells may be described by which of the following?
D: Smooth muscle is not striated, and it is involuntary and has one nucleus.
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13. Where are the semimembranosus and semitendinosus muscles located?
B: They are two of the three “hamstring” muscles on the dorsal thigh, the other being the biceps femoris.
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14. Smooth muscle is different from skeletal muscle because smooth muscle:
A: Smooth muscle occurs in the walls of tubes, whereas skeletal muscle does not
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15. Which of the events below is the FIRST to occur prior to a muscle cell contracting?
D: The release of Ca+ from where it is stored (in the sarcoplasmic reticulum) is necessary before the active binding site of actin can be exposed.
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16. By what name is the plasma membrane of a muscle cell known?
D: “Sarco-” refers to flesh (muscle); “lemma-” refers to sheath (membrane) around the cell.
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17. During muscle cell contraction, what happens because of Ca++ binding to troponin?
A: Troponin causes tropomyosin (which covers the binding site of actin) to be shifted away.
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18. Of the events that lead to myofilaments sliding over each other, which of the following happens first?
C: Ca must first enter the cytoplasm in order to bind with troponin. Once the binding site is exposed, the myosin head may engage the site. Prior to engagement, ATP must be hydrolysed to ADP.
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19. Which of the following muscle cell structures is the longest?
B: A muscle cell is a bundle of myofibrils. Myofibrils contain many sarcomeres joined end to end. Within sarcomeres are found (the shorter) thick and thin myofilaments.
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20. Which of the following muscles is named according to its origin and insertion?
C: The origin is on the sternum and clavicle (sternocleido-), while the insertion (on the “moving bone”) is to the mastoid process of the temporal bone.
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