Chapter Ten: Part One

Question 1

Explain contractility and extensibility

Answer 1

Extensibility is the quality of being able to stretch or extend
Contractility allows muscle tissue to pull on its attachment points and shorten with force

Question 2

Describe the different types of muscle

Answer 2

Skeletal muscle fibers are multi-nucleated structures that compose the skeletal muscle. Cardiac muscle fibers each have one to two nuclei and are physically and electrically connected to each other so that the entire heart contracts as one unit. In smooth muscle, the cytoplasm of a smooth muscle fiber has a uniform, no striated appearance.

Question 3

Describe the layers of connective tissues packaging a skeletal muscle

Answer 3

Each skeletal muscle has three layers of connective tissue that enclose it and provide it structure. Each muscle is wrapped in a sheath of dense, irregular connective tissue called the epimysium. The middle layer of connective tissue is called the perimysium. Inside each fascicle, each muscle fiber is encased in a thin connective tissue layer of collagen and reticular fibers called the endomysium.

Question 4

Explain how muscles work with tendons to move the body

Answer 4

The collagen in the three tissue layers intertwines with the collagen of a tendon. At the other end of the tendon, it fuses with the periosteum coating the bone.

Question 5

Describe the excitation-contraction coupling

Answer 5

For a skeletal muscle fiber to contract, its membrane must first be “excited” - in other words, it must be stimulated to fire an action potential. The muscle fiber action potential, which sweeps along the sarcolemma as a wave, is “coupled” to the actual contraction through the release of calcium ions from the SR