EXAM 4 246 a&p

matching

1. A quick cycle of contraction and relaxation of the muscle is called a twitch. 2. With moderately frequent stimulation, muscle relaxes fully between contractions, but successive twitches are stronger, a phenomenon known as treppe. 3. When the frequency is progressively higher, the muscle does not have time to relax. 4. At an even higher frequency, the muscle exhibits a state of continual contraction, called tetanus . 5. The muscle will eventually fatigue and the muscle tension will then decline.

A prime mover (agonist) is the name given to a muscle producing the majority of the torque (force) during a joint movement. Synergists aid the agonist in producing a joint movement and are often smaller or mechanically disadvantaged compared to the prime mover. A muscle that produces the opposite action as the prime mover and thus opposes the joint action caused by the prime mover is known as an antagonist

During knee extension, the quadriceps are agonists and the hamstrings are the antagonists. However, during knee flexion, this relationship flips. During controlled movements, it is necessary to stabilize accessory joints, which is the job of muscles referred to as fixators.

Check all that are a function of skeletal muscle tissue.

-Body movement -Maintenance of posture -Heat production -Regulating elimination of materials -Protection and support

Select the characteristics of slow-twitch muscle fibers. Check all that apply.

-Myoglobin is present in high concentration. -Mitochondria are numerous in these fibers.

Check all of the statements that are true regarding the changes that occur in the muscular system as a result of aging.

-The elasticity of skeletal muscle decreases. -There is a decrease in muscle fiber diameter.

Place the events involved in muscle contraction in the correct order.

1. A nerve impulse causes ACh release at a neuromuscular junction. 2.ACh binds receptors on the motor end plate, initiating a muscle impulse. 3.Calcium ions bind to troponin, causing tropomyosin to move and expose active sites. 4.Myosin heads attach to actin and form crossbridges. 5.A cyclic "attach, pivot, detach, return" event occurs. 6.Calcium ions are moved back into the sarcoplasmic reticulum by ATP-driven pumps. 7.Myofilaments passively return to their original state.

Match: 1. Striated and multinucleated 2. Autorhythmic with gap junctions 3. No striations and involuntary

1. Skeletal 2. Cardiac 3. Smooth

Check all that are proteins of thin filaments.

Actin Titin (connectin) Troponin Tropomyosin

Hold your arm out so that it is completely extended. The triceps brachii is causing the extension, so it is acting as what?

Agonist

Your school wins the homecoming football game against its biggest rival. You watch as the smallest cheerleader tries to lift up the heaviest linebacker in her excitement. As she strains against his 300-pound load and does not move him, what type of muscle contraction are her muscles experiencing?

Isometric

Which of the following will increase during strenuous muscular activity?

Lactate

Small Motor Units Writing a note playing a piano following words on a page with your eyes

Large Motor Units climbings stairs sitting up in a chair moving a piano

Which is a characteristic of skeletal muscle from the selections below?

Multinucleated

In a 1500-meter run, an event that may take about 5 to 6 minutes, ATP is supplied by which energy sources?

Phosphagens, anaerobic, and aerobic sources

Which of the following refers to a sustained muscle contraction?

Tetanus

Check all that are true statements regarding antagonists.

The stretching of the antagonist slows and controls the action of the agonist. The action of the antagonist opposes the action of the agonist.

Select all that are true regarding a resting muscle fiber.

There is more sodium outside the cell as compared to the sarcoplasm. Voltage-gated ion channels are closed.

All the muscle fibers under the control of a single motor axon are referred to as

a motor unit

If you were studying the neurotransmitter released from axon terminals at a neuromuscular junction, you would be studying

acetylcholine

The less movable attachment of a muscle is called its

origin

At the ends of muscles, the connective tissues merge to form a __________, which attaches the muscle to other structures.

tendon

The component of a muscle fiber that quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber is called the

transverse tubule (T-tubule).

Sprinting is a sport that requires an explosion of energy more than endurance. The best type of muscle fibers for this activity would be

fast-twitch fibers with fewer mitochondria and a lower blood supply.

The type of muscles in which the fascicles are at an oblique angle to the tendon, and the muscle fibers resemble a large feather is called

pennate

Myofilaments within myofibrils are arranged in repeating microscopic cylindrical units called ____________.

sarcomeres

Place the organizational level of muscle tissue in order, beginning with the entire muscle and ending with the smallest component.

1. Muscle 2. Fascicle 3. Muscle fiber 4. Myofibril 5. Myofilament

The source of energy for bonding between myosin and actin is

ATP

The typical skeletal muscle fiber contains several components that facilitate the production of ATP. Check all that apply.

Mitochondria Myoglobin Glycogen

A decrease in muscular activity or damage to neurons that attach to skeletal muscle can lead to a reduction in the size of muscle called

atrophy