* not completed

. Which of the following statements concerning the structure of muscle tissue is correct?

Skeletal muscle and cardiac muscle are both striated correct incorrect

Smooth muscle cells have no striations as they lack myosin filaments correct incorrect

The spread of excitation through a skeletal muscle fibre is brought about by a system of T-tubules. correct incorrect

The myofibrils of skeletal muscle are surrounded by the sarcoplasmic reticulum. correct incorrect

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. Skeletal muscle has a system of T-tubules while smooth muscle does not.

True correct incorrect

False correct incorrect

* not completed

. All muscle cells contain actin and myosin.

True correct incorrect

False correct incorrect

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. The muscle fibres of skeletal muscle are electrically coupled so that one nerve fibre can control the activity of several muscle fibres.

True correct incorrect

False correct incorrect

* not completed

. Which of the following statements concerning the role of Ca²⁺ in the contraction of skeletal muscle are correct?

The mitochondria act as a store of Ca²⁺ for the contractile process correct incorrect

Ca²⁺ released from the sarcoplasmic reticulum is essential for the contraction of skeletal muscle correct incorrect

A rise in intracellular Ca²⁺ allows actin to interact with myosin correct incorrect

The tension of a skeletal muscle fibre is partly regulated by G proteins. correct incorrect

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. The maximum power that can be developed by a skeletal muscle

Is independent of the initial length of the muscle correct incorrect

Occurs with an isometric contraction correct incorrect

Occurs when the muscle is moving a load at about one third of its maximum rate of shortening correct incorrect

Occurs when the muscle is shortening at its maximum rate correct incorrect

Depends on the load being moved by the muscle correct incorrect

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. The action potential of cardiac muscle fibres is initiated by action potentials in sympathetic nerve fibres.

True correct incorrect

False correct incorrect

* not completed

. Which of the following statements concerning cardiac muscle is correct?

The force of contraction is increased by circulating adrenaline correct incorrect

Heart muscle contracts in response to action potentials in the autonomic nerve fibres correct incorrect

The action potential is about 10-20 times as long as that of skeletal muscle correct incorrect

All of the Ca²⁺ required for contraction enters a myocyte during the plateau phase of the action potential correct incorrect

* not completed

. Which of the following statements concerning the contraction of smooth muscle are correct?

Smooth muscles are innervated by somatic nerves. correct incorrect

All smooth muscles behave as a functional syncytium. correct incorrect

Some smooth muscles may contract without an action potential correct incorrect

Smooth muscle fibres have no specialized neuromuscular junctions correct incorrect

The contraction of smooth muscle is regulated by calcium in the same manner as cardiac muscle. correct incorrect