Chapter 07

Instructions

Choose your answers from a-d by clicking the radio button next to each choice and then press 'Submit' to get your score.

The following statements relate to the structure of muscle tissue. Which one is correct?

a) Skeletal muscle has the same structure as cardiac muscle.

b) Smooth muscle cells have no striations as they lack myosin filaments.

c) Smooth muscle has a system of T-tubules.

d) The myofibrils of skeletal muscle are surrounded by the sarcoplasmic reticulum.

The following statements relate to the role of Ca²⁺ in the contraction of skeletal muscle. Which one is correct?

a) The mitochondria act as a store of Ca²⁺ for the contractile process.

b) Ca²⁺ entry across the plasma membrane is important in sustaining the contraction of skeletal muscle.

c) A rise in intracellular Ca²⁺ allows actin to interact with myosin.

d) The tension of a skeletal muscle fiber is partly regulated by G proteins.

In cardiac muscle:

a) the force of contraction is increased by circulating epinephrine.

b) heart muscle contracts in response to action potentials in the autonomic nerve fibers.

c) the action potential has the same duration as that of skeletal muscle.

d) all of the Ca²⁺ required for contraction enters a myocyte during the plateau phase of the action potential.

The maximum power developed by a skeletal muscle:

a) is independent of the initial length of the muscle.

b) Occurs with an isometric contraction.

c) depends on the load moved by the muscle.

Relating to smooth muscle, which one of the following three options is correct?

a) Individual muscle fibers are innervated by autonomic nerves.

b) All smooth muscles behave as a single motor unit.

c) Some smooth muscles may contract without an action potential.