Which ion has the highest concentration in the T-tubule of a skeletal muscle cel

Question

Which ion has the highest concentration in the T-tubule of a skeletal muscle cell? A) calcium B) magnesium C) sodium D) potassium E) None of the above. Once the terminal cisternae are depolarized, _____enters the sarcoplasm through _____ A) calcium, voltage gated channels B) calcium, chemically gated channels C) calcium, the calcium pump D) sodium, the sarcoplasmic reticulum E) sodium, the sodium-potassium pump When calcium is elevated in the sarcoplasm of a skeletal muscle cell, calcium binds _____resulting in _____ A) tropomyosin, troponin being pulled off the active sites located on actin B) troponin, tropomyosin being pulled off the active sites located on myosin C) tropomyosin, troponin being pulled off the active sites located on myosin D) titan, tropomyosin being pulled off the active sites located on actin E) troponin, tropomyosin being pulled off the active sites located on actin Following the power stroke, ATP binds _____ resulting in _____ A) tropomyosin, troponin being pulled off the active sites located on actin B) troponin, tropomyosin being pulled off the active sites located on myosin C) the myosin head, detachment of the myosin head from actin and myosin resumes its low energy state D) the myosin head, attachment of the myosin head to actin and myosin resumes its high energy state E) the myosin head, detachment of the myosin head from actin and myosin resumes its high energy state What would happen to a skeletal muscle cell if all the calcium pumps (calcium ATPase) were inhibited A) The cell would contract to complete tetanus. B) The cell would enter the relaxation phase. C) The cell would function normally. D) The cell could not contract. E) The cell would contract but the contraction would be weaker than normal (low tension). Which filaments actively shorten when a skeletal muscle cell contracts? A) the filaments the B) actin C) the filaments in the A-Band. D) myosin E)None of the above Lets get back to Joe. He decided to take another drink from the can of Red Bull on his desk so he picks up the can raises it to his lips, take drink and lowers the can back to the surface of his desk. As Joe lifted the can his biceps brachii muscle performed a (an) _____contraction. A) isotonic B) hypertonic C) isometric D) hypotonic E) tetanic

Explanation / Answer

6. A) calcium

7. A) Calcium, voltage gated channels

8. B) troponin, tropomyosin being pulled off the active sites located on myosin

10. E) The cells would contract but the contraction would be weaker than normal

11. B) actin

The action filaments contract during the sliding of the muscle fibres past the myosin filaments and is given by the sliding filament theory.

12. E) tetanic

The tetanic contractions are sustained muscle contractions that occur during the innervation ir the motor neurons when action potentials are emitted by the skeletal muscle at very high rates.

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