Physio - Ch. 12 Muscles - Quiz

Put these events in the correct chronological sequence: 1. End-plate potentials trigger action potentials. 2. Transverse tubules convey potentials into the interior of the cell. 3. Acetylcholine binds to receptors on the motor end plate. 4. Ca2+ is released from the sarcoplasmic reticulum.

3, 1, 2, 4

Match from the following list. A. A band B. I band C. Z disk D. H zone E. M line The band with the most overlap between thick and thin filaments, which unevenly scatters light leading to its' dark appearance.

A band

________ is composed of multiple globular molecules polymerized to form long chains or filaments.

Actin

The contraction cycle is triggered by the rise in ________ released from the sarcoplasmic reticulum (SR).

Ca2+

Match from the following list. A. A band B. I band C. Z disk D. H zone E. M line The lightest color bands of the sarcomere, comprised only of thin filaments.

I band

________ is the backup energy molecule that can be rapidly converted to ATP in active skeletal muscle.

Phosphocreatine

Match from the following list. A. A band B. I band C. Z disk D. H zone E. M line The structures that serve as the attachment site for the thin filaments and mark the boundaries for one sarcomere.

Z Disk

Each myosin head has a binding site for

actin and ATP.

In order for high force crossbridges to form in contracting skeletal muscle, calcium must

bind to troponin which moves the tropomyosin.

As ATP binds to the myosin head at the beginning of a muscle contraction cycle, the myosin head immediately

detaches from actin.

Match the structures with the accurate description. A. muscle fiber B. fascicle C. sarcolemma D. myofibril E. t-tubules a bundle of adjacent muscle cells

fascicle

Which fibers fatigue sooner? -slow-twitch fibers -fast-twitch fibers

fast-twitch fibers

Motor units that control skeletal muscles involved with fine motor movements (eye muscles or the hands) have ________ muscle fibers than motor units that control more gross movements (gastrocnemius muscle of the lower leg).

fewer

In order for the bicep muscle to shorten, the force applied by the muscle must be ________ the load applied at the hand.

greater than

A contraction that generates enough force to move a load is known as ________, whereas one that generates force that equals the load is known as ________.

isotonic, isometric

The brief period of time between the beginning of the action potential in the muscle and the beginning of contraction is referred to as the

latent period.

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers? -high capillary density only -long contraction duration only -few mitochondria only -long contraction duration and high capillary density -long contraction duration, few mitochondria, and high capillary density

long contraction duration and high capillary density

Match the structures with the accurate description. A. muscle fiber B. fascicle C. sarcolemma D. myofibril E. t-tubules a single muscle cell

muscle fiber

Match the structures with the accurate description. A. muscle fiber B. fascicle C. sarcolemma D. myofibril E. t-tubules highly organized bundles of contractile proteins within a skeletal muscle cell

myofibril

A motor unit consists of

one neuron and all the skeletal muscle fibers it controls.

Skeletal muscle fibers with the greatest endurance rely on ________ for energy.

oxidative phosphorylation

The function of transverse tubules is to -conduct ATP molecules out of the mitochondria throughout the sarcoplasm. -ensure a supply of glycogen throughout the muscle sarcoplasm. -store Ca2+ ions inside the muscle fiber. -rapidly conduct action potentials to the interior of the muscle fiber.

rapidly conduct action potentials to the interior of the muscle fiber.

The hydrolysis of ATP causes myosin to immediately -release ADP. -release from the actin. -rotate into a position (cocked) to bind to actin. -bind more tightly to the actin (rigor). -swivel, moving the actin molecule.

rotate into a position (cocked) to bind to actin.

Match the structures with the accurate description. A. muscle fiber B. fascicle C. sarcolemma D. myofibril E. t-tubules the muscle cell membrane

sarcolemma

Striated muscles are so-called because of a repeating pattern of light and dark bands. One repeating unit of the banding pattern is called a

sarcomere

Match the structures with the accurate description. A. muscle fiber B. fascicle C. sarcolemma D. myofibril E. t-tubules inward extensions of the muscle cell membrane

t-tubules

Skeletal muscle cells are usually attached to bone by

tendons

The I band contains myosin only. thick filaments only. thin filaments only. thick and thin filaments.

thin filaments only