Chapter 12

A skeletal muscle is composed of a bundle of ________, each composed of many muscle fibers wrapped by connective tissue

What structure, composed of connective tissue, transmits force from contracting skeletal muscle to bone?

The fundamental repeating unit of the myofibril, called a ________, gives skeletal muscle its striated appearance and is bordered by ________.

What is the region of the striated muscle's banding patterns that contains only the connections between the tails of myosin molecules and is the mid-point of the sarcomere?

The contractile portion of the thin filament is composed of what protein?

What is the regulatory protein component of the thin filament that binds to calcium, thereby initiating skeletal muscle contraction?

Which of the following is a structural protein that extends along each thick filament from M line to Z line?

The shortening of a skeletal muscle fiber during contraction involves which of the following?

During skeletal muscle contraction, as the muscle shortens, the thick and thin filaments

When a skeletal muscle is passively stretched, that cell has a tendency to spring back once the force that was stretching the muscle is removed due to

The repeated, oscillating interaction between actin and myosin which results in the generation of force by a skeletal muscle cell is called what?

What converts the myosin head into the high-energy state?

The release of an inorganic phosphate from the myosin molecule directly results in which of the following?

In order for crossbridge cycling to occur, the actin-myosin complex must be broken by which of the following?

The sequence of events that links the muscle's action potential to changes in skeletal muscle force development is called what?

During skeletal muscle contraction, multiple crossbridge cycles are occurring between the same thick and thin filament. Which of the following best describes this process?

Contraction of skeletal muscle fibers is stimulated by what type of neuron?

Which of the following is NOT a specialization observed at the neuromuscular junction?

Increases in the amount of cytoplasmic calcium required to initiate a muscle contraction are mediated by the coupling between a ________ on the T tubule and a ________ on the membrane of the sarcoplasmic reticulum.

Which of the following is the voltage sensor that initiates an increase in cytoplasmic calcium in response to an action potential?

The binding of calcium to troponin will directly allow which of the following?

What area of a sarcomere shows up as light striations when viewed under a microscope?

Which of the following best describes the interaction between transverse (T) tubules and the sarcoplasmic reticulum in skeletal muscle contraction?

During the cross-bridge cycle, ATP binding to myosin causes which of the following?

What is the function of T tubules?

What is a motor unit?

In order to allow discrete contractile events to occur, calcium is rapidly removed from the cytoplasm via

Which of the following is not part of the process whereby skeletal muscles relax?

What enzyme catalyzes the reaction that creates creatine phosphate?

Since the creatine phosphorylation reaction is substrate driven, an increase in the concentration of creatine within a skeletal muscle fiber will directly have what effect?

During intense (heavy) exercise, the initial ability of oxidative phosphorylation to provide enough ATP for the sudden demand of increased force generation by the skeletal muscle is ________, thereby causing the muscle fiber to quickly and massively boost its energy production from ________ until oxygen delivery and other mechanisms come up to speed.

As the intensity of exercise increases (and the potential gap between energy demand and creation threatens to widen), the muscles quickly underwrite their escalating energy demands by augmenting oxidative with substrate-level phosphorylation, resulting in the increased generation of which of the following?

When an action potential is generated within a motor neuron,

Which is the longest phase of a twitch?

Which of the following is NOT part of the explanation for the all-or-nothing property of an isometric twitch contraction of skeletal muscle?

Which of the following is a property of isometric skeletal muscle contraction?

Which of the following is a property of isotonic skeletal muscle contraction?

Which of the following statements about excitation-contraction coupling in skeletal muscle is FALSE?

Which of the following statements about end-plate potentials is FALSE?

Which of the following best describes an isotonic contraction?

The speed with which the skeletal muscle generates force is determined primarily by

Which of the following is the property of skeletal muscle whereby an increase in the frequency of action potentials enhances the force developed by the muscle cell?

The tension produced during skeletal muscle contraction can be increased by all of the following EXCEPT

Which of the following statements about summation and tetanus is FALSE?

Once a skeletal muscle cell begins to shorten during an isotonic twitch contraction,

Which of the following conditions will result in a skeletal muscle that produces a greater amount of force?

Which of the following is NOT an accurate description of specific muscle fiber types?

As skeletal muscle is further stretched beyond the length where optimum force is developed,

As the sarcomere length of skeletal muscle is reduced beyond the length where optimum force is developed,

In the body, the sarcomere length of skeletal muscle cells is usually

Which of the following does NOT influence the force generated by an individual muscle fiber?

What is an increase in the number of active motor units that would increase the force developed by a skeletal muscle called?

Contraction of motor units in a(n) ________ manner allows a muscle to maintain a smooth level of force for a duration of time without fatiguing.

Which of the following BEST describes the relationship between motor neuron size, motor unit size, and order of recruitment?

A muscle is stimulated at a frequency that allows the muscle to relax completely between contractions. However, the amount of tension increases with each contraction. What is this called?

The mechanism responsible for the size principle involves

Which of the following is NOT a property of glycolytic fibers as compared to oxidative fibers?

What molecule, present primarily within oxidative skeletal muscle cells, acts as an oxygen buffer due to its ability to bind oxygen?

What causes some muscle fibers to appear red and dark?

What is the site where a muscle attaches to a stationary bone called?

What connects muscles to bone?

Relative to the triceps muscle, the biceps is its

What type of receptor detects muscle length?

What is an annulospiral ending?

What type of efferent neuron innervates intrafusal muscle fibers?

Which of the following statements is TRUE regarding activation of alpha and gamma motor neurons?

Which of the following is the correct order of muscle fiber recruitment, from first to last?

Which of the following muscle types has the slowest contraction time?

Which of the following mechanisms does NOT account for the decrease in force development by muscle cells during sustained force development?

Which of the following is NOT an adaptation of skeletal muscle that would be observed in response to aerobic training?

Where are gap junctions commonly found?

Which of the following is true of ALL muscle types?

In smooth muscle, calcium triggers contraction by binding to what protein?

Calcium binding to calmodulin causes phosphorylation by myosin light chain kinase of what protein in what type of muscle?

Which of the following adaptations does NOT generally occur with aerobic exercise?

The interaction between actin and myosin in smooth muscle requires

What is the source of variability in the response of smooth muscle cells from different organs to autonomic nervous activity (some relax to sympathetic nervous output while others contract)?

Which of the following could cause a pacemaker potential?

Which of the following stores calcium to be released for muscle contraction?

Which of the following transmits action potentials to the interior of the muscle cell to trigger calcium release?

Which of the following generates the mechanical force of a muscle through crossbridge cycling?

Which of the following attaches muscle to bone?

What is the functional unit of skeletal muscle?

Which of the following contains ryanodine receptors?

Which of the following contains DHP receptors?

Which of the following contains nicotinic cholinergic receptors?

Which of the following extends the length of the thick filaments?

What region of thick filaments has no overlap with thin filaments?

What is the region of thin filaments that has no overlap with thick filaments called?

What anchors thin filaments together?

What anchors thick filaments together?

Which of the following appears as light bands under the microscope?

Which of the following appears as dark bands under the microscope?

Which protein binds calcium in smooth muscle cells?

What binds calcium in skeletal muscle cells?

What binds calcium in cardiac muscle cells?

What are the elastic fibers that anchor thick filaments in place?

What is the enzyme that modulates the ability of myosin to bind actin in smooth muscle?

Which type of skeletal muscle fiber contains a high concentration of mitochondria?

Which type of skeletal muscle fiber contains high shortening velocities?

Which type of skeletal muscle fiber catalyzes hydrolysis of ATP slowly?

Which type of skeletal muscle fiber fatigues rapidly?

Which type of skeletal muscle fiber contains myoglobin?

Which type of skeletal muscle fiber has most of its energy come from substrate-level phosphorylation?

Which type of skeletal muscle fiber is white muscle?

Which muscle type contains actin and myosin?

Which muscle type contracts by the sliding-filament mechanism?

Where does calcium bind to troponin?

Calcium binds to calmodulin where?

Some muscle cells have pacemaker activity. These include

Which muscles are innervated by autonomic nervous system?

Gap junctions are present between which cells?

Calcium for contraction comes entirely from the sarcoplasmic reticulum in which of the following?

In which muscle type do thick and thin filaments organize into sarcomeres?

What is the structure indicated by the number 1 in Figure 12.1 and what is its functional significance

What is the structure indicated by the number 2 in Figure 12.1 and what is its functional significance?

What is the structure indicated by the number 3 in Figure 12.1 and what is its functional significance?

What is the structure indicated by the number 4 in Figure 12.1 and what is its functional significance?

What is the structure indicated by the number 5 in Figure 12.1 and what its functional significance?

What is the structure indicated by the number 6 in Figure 12.1 and what is its functional significance?

Which structure(s) in Figure 12.1 would be altered by muscle shortening?

The continuation of the sarcolemma that penetrates the interior of the muscle fiber and thereby facilitates the release of calcium from the sarcoplasmic reticulum is called what?

What is the protein component of the thin filament that blocks the myosin-binding site on the actin monomer?

Troponin is a complex of three proteins that bind to tropomyosin, calcium, and

Calcium is stored in what region of skeletal muscle cells?

The three proteins found to make up the thin filaments are actin, tropomyosin, and

Heavy intensity exercise generates what byproduct that contributes to fatigue?

The time between the occurrence of an action potential in skeletal muscle and the onset of tension is called what?

Mechanisms whereby force of skeletal muscle fibers can be altered include all of the following EXCEPT

The two types of sensory endings found in muscle spindles are the annulospiral endings and

What type of motor neuron innervates intrafusal muscle fibers?

What is the antagonistic muscle to the triceps?

What are the three types of muscle fibers that are found in all skeletal muscles?

Postural muscles of the legs and back tend to have a high proportion of what fiber type?

In smooth muscle, calcium binds to calmodulin and then activates the enzyme

The decreased ability of a muscle to maintain a constant force of contraction during repetitive stimulation is called what?

In smooth muscle, the structures analogous to Z lines in skeletal muscle are called

Intercalated disks contain what type of special junctions?