Human Anatomy & Physiology: A&P Chapter 9 Muscles and Muscle Tissue Flashcards

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Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of the following mechanisms ensures a rapid and efficient removal of acetylcholine?

The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction?

Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________.

Calcium entry into the axon terminal triggers which of the following events?

Acetylcholine binds to its receptor in the sarcolemma and triggers __________.

Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why?

Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?

Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?

A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?

What is name given to the regularly spaced infoldings of the sarcolemma?

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?

What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

What structure is the functional unit of contraction in a skeletal muscle fiber?

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

How does the myosin head obtain the energy required for activation?

What specific event triggers the uncovering of the myosin binding site on actin?

When does cross bridge cycling end?

Between which two points would there be substantial amounts of both the proteins actin and myosin?

The region between which two points corresponds to the entire A band?

The region between which two points corresponds to the I band?

2 and 3
2 and 5
3 and 5

Which event is most significant in initiating the "wave of depolarization" shown in event C?

In which phase in the figure would the net movement of Ca²⁺ into the sarcoplasmic reticulum (SR) be greatest?

What result would be expected if an additional stimulus, equal in intensity to the first, were to be applied to the muscle at the 60 millisecond (ms) time point?

Excitation-contraction coupling includes all EXCEPT which of the following events?

Which of the following factors influence the velocity and duration of muscle contraction?

The strongest muscle contractions are normally achieved by ________.

Which of the following is not a role of ionic calcium in muscle contraction?

What is the most distinguishing characteristic of muscle tissue?

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________.

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment.

Eccentric contractions are more forceful than concentric contractions.

Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy.

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.

Binding of calcium to calmodulin is a step in excitation-contraction coupling of ________ cells.

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.

Once a motor neuron has fired, all the muscle fibers in a muscle contract.

Which of the following is CORRECTLY paired?

In an isotonic contraction, the muscle ________.

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.

Which lettered protein functions as a motor protein?

In which phase of the muscle twitch shown in the above figure would the maximum amount of ATP be consumed by myosin head groups?

Peristalsis is characteristic of smooth muscle.

What structure in skeletal muscle cells functions in calcium storage?

The distance between Z discs ________ during muscle contraction.

Thick myofilaments are made of ________.

Which type of muscle CANNOT contract without being stimulated by the nervous system?

Slow oxidative muscle fibers are best suited for ________.

What event directly triggers the release of neurotransmitter shown in A?

What specific neurotransmitter is released from the axonal terminus as shown in A?

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

The protein troponin is shown in this figure to be bound to which substance?

The smallest contractile unit of a muscle fiber is ________.

The muscle cell membrane is called the ________.

A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.

What is a cross bridge cycle?

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.

The connective tissue that covers structure A is continuous with which of the following?

The force of a muscle contraction is NOT affected by __________.

Muscle tone is ________.

The response of a motor unit to a single action potential of its motor neuron is called ________.

The oxygen-binding protein found in muscle cells is ________.

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

Which organelle contains the contractile elements found in skeletal muscle?

What is the role of tropomyosin in skeletal muscles?

Which statement accurately describes the event indicated by B?

Muscle contraction will always promote movement of body parts regardless of how they are attached.

What part of the sarcolemma contains acetylcholine receptors?

During muscle contraction, myosin cross bridges attach to which active sites?

What is the functional unit of a skeletal muscle called?

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.

Smooth muscles are able to regenerate throughout life.

When muscle cells break down glucose to generate ATP under oxygen deficient conditions, they will form ________.

Which structure corresponds to a single fascicle?

Most skeletal muscles contain ________.

A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.

The contractile units of skeletal muscles are ________.

Choose the FALSE statement.

Which of the following is the smallest structural unit in which the distinctive striated bands characteristic of skeletal muscle are observed?

What produces the striations of a skeletal muscle cell?

Which protein inhibits interaction between actin and myosin to prevent skeletal muscle contraction; and which ions remove the inhibition?

Which of the following describes the neurons shown in this figure?

Which of the following is TRUE?

Which type of muscle CANNOT contract without being stimulated by the nervous system?

The sliding filament model of contraction states that ________.

The major function of the sarcoplasmic reticulum in muscle contraction is to ________.

The force of a muscle contraction is NOT affected by __________.

The protein actin is indicated by which letter?

Muscle tissue has all of the following properties except ________.

In an isotonic contraction, the muscle ________.

Which of the following surrounds the individual muscle cell?

What event directly triggers the release of neurotransmitter shown in A?

What is the functional unit of a skeletal muscle called?

The contractile units of skeletal muscles are ________.

The smallest contractile unit of a muscle fiber is ________.

The first step toward generating a skeletal muscle contraction is ________.

Which organelle contains the contractile elements found in skeletal muscle?

Most skeletal muscles contain ________.

The term aponeurosis refers to ________.

Muscle tissue does NOT ________.

What special feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

In the figure above, which structure corresponds to a single skeletal muscle cell?

If both of the neurons in the figure were activated, more muscle fibers would contract than if either neuron alone were active. This mechanism for control of the force of muscle contraction is known as ______.

The sliding filament model of contraction involves ________.

Which statement accurately describes the event indicated by B?

Which lettered protein functions as a motor protein?

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.

Choose the FALSE statement.

Which protein inhibits interaction between actin and myosin to prevent skeletal muscle contraction; and which ions remove the inhibition?

Which muscle characteristic describes the ability of muscle to respond to a stimulus?

Binding of calcium to calmodulin is a step in excitation-contraction coupling of ________ cells.

The oxygen-binding protein found in muscle cells is ________.

One of the important functions of skeletal muscle contraction is production of heat.

What specific neurotransmitter is released from the axonal terminus as shown in A?

In which phase of the muscle twitch shown in the above figure would the maximum amount of ATP be consumed by myosin head groups?

What structure in skeletal muscle cells functions in calcium storage?

Muscle contraction will always promote movement of body parts regardless of how they are attached.

Slow oxidative muscle fibers are best suited for ________.

What is the functional role of the T tubules?

The force of muscle contraction is controlled by multiple motor unit summation or recruitment.

Which of the following is the smallest structural unit in which the distinctive striated bands characteristic of skeletal muscle are observed?

A contraction in which the muscle does not shorten but its tension increases is called isometric contraction.

The connective tissue sheaths of skeletal muscle, in order from internal to external, are the ________.

The protein troponin is shown in this figure to be bound to which substance?

The smallest contractile unit within skeletal muscle would correspond to the distance between which two points in the figure?

Which of the following describes the neurons shown in this figure?

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.

Which muscle cells have the greatest ability to regenerate?

Once a motor neuron has fired, all the muscle fibers in a muscle contract.

The distance between Z discs ________ during muscle contraction.

Creatine phosphate functions in the muscle cell by ________.

What is the role of tropomyosin in skeletal muscles?