Module 2: Section 9.03

Match the following component of a muscle fiber with its description: Area of the sarcomere with overlapping thick and thin filaments.

A band

Identify the part of thick or thin filaments in skeletal muscle indicated by "D."

Actin subunits

Which of the following provides the final "go signal" for contraction?

Calcium ions

Which of the following allows recoil of the muscle fiber when contraction ends?

Elastic filament (titin)

Match the following component of a muscle fiber with its description: Area in the center of the A band containing only thick filaments.

H zone

Which of the following is a special adaptation present in skeletal muscle cells, but absent in most other cells?

Muscle cells have myoglobin; most other cells do not.

Match the following cellular component of a skeletal muscle fiber with its description: Rodlike contractile element within a muscle fiber containing myofilaments.

Myofibril

Match the following muscle chemical with the correct name: Oxygen storage molecule in skeletal muscle.

Myoglobin

Identify the part of thick or thin filaments in skeletal muscle indicated by "A."

Portion of a thick filament

Match the following cellular component of a skeletal muscle fiber with its description: Plasma membrane of skeletal muscle fiber

Sarcolemma

Match the following cellular component of a skeletal muscle fiber with its description: Cytoplasm of a skeletal muscle fiber.

Sarcoplasm

Which of the following are inward invaginations of the sarcolemma that run deep into the cell between the terminal cisterns?

T tubules

In the sliding filament model of contraction, which of the following occurs when the muscle cell shortens?

The distance between successive Z discs shortens.

The thin myofilaments of skeletal muscle are composed chiefly of __________.

actin

The linking of thick and thin filaments together is called _____________.

forming a cross bridge

A sarcomere is part of a(n) __________.

myofibril

"Cross bridges" that link between the thick and thin filaments directly involve__________.

myosin

In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and __________.

myosin

The functional unit of contraction in a skeletal muscle fiber is the __________.

sarcomere

Myofibrils are composed of repeating contractile elements called __________.

sarcomeres