exam 3

Where is ATP is consumed? 8 3 1 2 7

3

Where are the myosin molecules located? 4 5 6 7 8

5

Where would calcium ions be predominately found? 1 2 4 8 9

9

Aerobic metabolism normally provides ________ percent of the ATP demands of a resting muscle cell. 25 50 70 95 100

95

The region of the sarcomere containing the thick and thin filaments is the A band. M line. Z line. I band. H band.

A band.

Which of the following statements is/are not true regarding human muscles? Eye muscles are composed entirely of fast fibers. Slow fibers are abundant in the calf muscles. Fast fibers are high in myoglobin. Most have both slow and fast fibers. Slow fibers are abundant in the back muscles.

Fast fibers are high in myoglobin.

________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue. Myoblasts Multinucleate cells Myofibrils Myosatellite cells Myofilaments

Myosatellite cells

When a skeletal muscle fiber contracts, which of the following does not occur? The width of the A band remains constant. The H bands and I bands get smaller. The Z lines get closer together. Myosin and actin filaments decrease in length. The zones of overlap get larger.

Myosin and actin filaments decrease in length.

Name the three types of muscle tissue, identify where they are found, and list their functions. (Module 9.1A) Skeletal muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Cardiac muscle is directly or indirectly attached to bones and enables movement of the body. Smooth muscle forms the heart and propels blood.Skeletal muscle forms the heart and propels blood. Cardiac muscle is directly or indirectly attached to bones and enables movement of the body. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels.Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels.Skeletal muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Cardiac muscle forms the heart and propels blood. Smooth muscle is directly or indirectly attached to bones and enables movement of the body.Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Smooth muscle forms the heart and propels blood.

Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood.

What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle fiber? (Module 9.2C) The plasma membrane is called the neurolemma and the cytoplasm is called the neuroplasm. The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm. The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasmic reticulum. The plasma membrane is called the endomysium and the cytoplasm is called the soma. The plasma membrane is called the epimysium and the cytoplasm is called the myoplasm.

The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm

Describe the connective tissue layers associated with skeletal muscle tissue. (Module 9.2B) The epimysium divides the skeletal muscle into fascicles; the perimysium surrounds the entire muscle; the endomysium surrounds individual muscle fibers.The epimysium divides the skeletal muscle into fascicles; the perimysium surrounds individual muscle fibers; the endomysium surrounds the entire muscle.The epimysium surrounds individual muscle fibers; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds the entire muscle.The epimysium surrounds the entire muscle; the perimysium surrounds individual muscle fibers; the endomysium divides the skeletal muscle into fascicles.The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers.

The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers.

Describe the neuromuscular junction. (Module 9.6A) The neuromuscular junction is where the dendrites of a sensory neuron receive inputs from a skeletal muscle fiber. The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length. The neuromuscular junction is where the axon terminals of a sensory neuron receive inputs from a skeletal muscle fiber. The neuromuscular junction is where the cell body of a motor neuron interact with the skeletal muscle fiber at one end. The neuromuscular junction is where the dendrites of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length.

The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length.

The dense layer of connective tissue that surrounds an entire skeletal muscle is the tendon. perimysium. fascicle. endomysium. epimysium.

epimysium.

Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives. hydrolysis apoptosis exocytosis endocytosis sodium

exocytosis

The synchronous contraction of a single motor unit is known as a(n) muscle action potential. twitch. fasciculation. asynchronous motor unit summation.cross-bridge.

fasciculation.

Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of slow fibers. intermediate fibers. fatty muscles. red muscles. fast fibers.

fast fibers.

During the Cori cycle in the liver, lactate is produced from glucose. lactate is shuffled to muscle cells. glucose is produced from lactate. lactate is produced from pyruvic acid. glucose is released from glycogen.

glucose is produced from lactate.

Muscle fibers differ from "typical cells" in that muscle fibers plasma membrane. have many nuclei. lack mitochondria are very small. All of the answers are correct.

have many nuclei.

Each skeletal muscle fiber contains ________ myofibrils. 50 to 100 100 to 150 150 to 200 200 to 500 hundreds to thousands

hundreds to thousands

If the membrane potential of a neuron is -80 mV, it is repolarized. hyperpolarized during the refractory period at resting potential. depolarized. at threshold.

hyperpolarized during the refractory period

A muscle producing tension that peaks but falls to only intermediate stimulus rates is said to be in incomplete tetanus. complete tetanus. treppe. wave summation .recruitment.

incomplete tetanus.

In an isotonic contraction, muscle tension exceeds the load and the muscle lifts the load. many twitches fuse into one. the peak tension is less than the load. tension rises and falls but the muscle length is constant.

muscle tension exceeds the load and the muscle lifts the load

In which of the following would the motor units have the fewest muscle fibers? muscles that control the eyes thigh muscles calf muscles muscles of the neck postural muscles of the back

muscles that control the eyes

To produce a contraction similar to the one in graph (b), the muscle is caused to produce isolated twitches. gradually warms up. is excited by a stimulus of increasing intensity. must be stimulated to the point of fatigue. must be stimulated again before it has relaxed from the previous stimulation.

must be stimulated again before it has relaxed from the previous stimulation.

Skeletal muscle fibers are formed from embryonic cells called myofibrils. myomeres. fascicles. sarcomeres. myoblasts.

myoblasts.

Name the proteins that make up a thick filament. (Module 9.4B) actin and titin actin and nebulin myosin and titin myosin and nebulin actin and dystrophin

myosin and titin

Cross-bridges are portions of troponin molecules. tropomyosin molecules. myosin molecules. calcium ions. actin molecules.

myosin molecules.

Each skeletal muscle fiber is controlled by a motor neuron at a single synaptic knob. synaptic cleft. neuromuscular junction. sarcomere. transverse tubule.

neuromuscular junction.

Communication between axons and muscle fibers occurs at specialized synapses called Z lines.active sites. neuromuscular junctions. motor end plates. junctional folds.

neuromuscular junctions.

At peak levels of muscle exertion, the mitochondria can supply ________ of the energy required by the muscle. more than half only about 10 percent all 80 percent only about one-third

only about one-third

Which of the following acts as an ATPase during the contraction cycle of muscle? the tail portion of the myosin molecule tropomyosin molecules troponin molecules actin molecules the head portion of the myosin molecule

the head portion of the myosin molecule

Within a resting skeletal muscle fiber, where is the greatest concentration of Ca2+? (Module 9.3C) bound to troponin inside the transverse tubulesterminal cisternae of the sarcoplasmic reticulum Z lines between adjacent sarcomeres zone of overlap of the sarcomere

tubulesterminal cisternae of the sarcoplasmic reticulum

The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n) tetanus. muscle action potential .unfused tetanus. twitch. end plate potential.

twitch.

Each thin filament consists of a rod-shaped structure with "heads" projecting from each end. two protein strands coiled helically around each other. chains of myosin molecules. six molecules in a rod-like structure.a double strand of myosin molecules.

two protein strands coiled helically around each other.

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called incomplete tetanus. complete tetanus. treppe. wave summation. recruitment.

wave summation.

Which of the following best describes the term "Z line"? largely made of myosin molecules protein that accounts for elasticity of resting muscle repeating unit of striated myofibrils storage site for calcium ions where thin filaments are anchored

where thin filaments are anchored

Which of the following is not a type of motor fiber? white-slow twitch white-fast twitch pink-fast twitch red-slow twitch type I

white-slow twitch

Explain two key concepts of the sarcomere length-tension relationship. (Module 9.9B) The smaller the zone of overlap, the greater the tension the muscle can develop; and (2) there is an optimum calcium concentration that will produce the greatest amount of tension. (1) The smaller the zone of overlap, the greater the tension the muscle can develop; and (2) there is an optimum range of actin and myosin overlap that will produce the greatest amount of tension. (1) The greater the zone of overlap, the greater the tension the muscle can develop; and (2) there is an optimum range of actin and myosin overlap that will produce the greatest amount of tension. (1) The greater the zone of overlap, the greater the tension the muscle can develop; and (2) there is an optimum calcium concentration that will produce the greatest amount of tension. (1) The greater the zone of overlap, the less tension the muscle can develop; and (2) there is an optimum range of actin and myosin overlap that will produce the greatest amount of tension.

(1) The greater the zone of overlap, the greater the tension the muscle can develop; and (2) there is an optimum range of actin and myosin overlap that will produce the greatest amount of tension.

The type of contraction in which the muscle fibers do not shorten is called concentric treppe .isometric. tetany.i sotonic.

.isometric.

Identify the structure where ATP is produced. 2 3 7 6 1

1

Define motor unit. (Module 9.10B) A motor unit is the sum total of all the muscle fibers in a whole muscle. A motor unit is the sensory neuron going away from and the motor neuron going to a skeletal muscle. A motor unit is a motor neuron and all the muscle fibers that it controls. A motor unit is the sum total of all the motor neurons going to a specific muscle. A motor unit is the maximum tension that a whole muscle can generate with maximum stimulation.

A motor unit is a motor neuron and all the muscle fibers that it controls.

Define tendon and aponeurosis. (Module 9.2A) A tendon is a bundle of collagen fibers that connects bones together, whereas an aponeurosis is a dense layer of collagen fibers surrounding an entire muscle. A tendon is a bundle of collagen fibers that connects a skeletal muscle to a bone, whereas an aponeurosis is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones. A tendon is a dense layer of collagen fibers surrounding an entire muscle, whereas an aponeurosis is a fibrous layer that divides the skeletal muscle into fascicles. A tendon is a bundle of collagen fibers that connects bones together, whereas an aponeurosis is a thin layer of areolar connective tissue that surrounds each muscle fiber. A tendon is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones, whereas and aponeurosis is a bundle of collagen fibers that connects a skeletal muscle to a bone.

A tendon is a bundle of collagen fibers that connects a skeletal muscle to a bone, whereas an aponeurosis is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones.

What molecule supplies the energy for a muscle fiber contraction? (Module 9.7A) creatine phosphate oxygen GTP ATP caffeine

ATP

Identify three sources of stored energy utilized by muscle fibers. (Module 9.12B) lactate, pyruvate, and glucose pyruvate, lactate, and GTP fatty acids, amino acids, and lactate fatty acids, amino acids, and glycogen ATP, creatine phosphate, and glycogen

ATP, creatine phosphate, and glycogen

Which statement about excitation-contraction coupling is incorrect? Calcium ion is released from the transverse tubule. Calcium ion is released from the sarcoplasmic reticulum. Tropomyosin moves to expose myosin binding sites on actin. Relaxation requires uptake of calcium ions by the sarcoplasmic reticulum. Troponin binds calcium ion and signals tropomyosin to move.

Calcium ion is released from the transverse tubule.

What causes calcium to be released from the sarcoplasmic reticulum? (Module 9.8A) Calcium is released when an action potential reaches the triad. Calcium is released when an action potential travels down the motor neuron. Calcium is released when acetylcholine binds acetylcholine receptors. Calcium is released when an action potential is generated at the neuromuscular junction. Calcium is released when myosin heads bind to actin.

Calcium is released when an action potential reaches the triad.

Contrast fast fibers with slow fibers in terms of diameter, glycogen reserves, myoglobin content, and relative abundance of mitochondria. (Module 9.14A) Compared with slow fibers, fast fibers have a smaller diameter, smaller glycogen reserves, more myoglobin, and more mitochondria. Compared with slow fibers, fast fibers have a smaller diameter, larger glycogen reserves, more myoglobin, and more mitochondria. Compared with slow fibers, fast fibers have a larger diameter, smaller glycogen reserves, less myoglobin, and more mitochondria. Compared with slow fibers, fast fibers have a larger diameter, larger glycogen reserves, less myoglobin, and relatively fewer mitochondria. Compared with slow fibers, fast fibers have a smaller diameter, smaller glycogen reserves, less myoglobin, and relatively fewer mitochondria.

Compared with slow fibers, fast fibers have a larger diameter, larger glycogen reserves, less myoglobin, and relatively fewer mitochondria.

Compare concentric and eccentric contractions. (Module 9.11B) Concentric contractions consist of equal lengths of time contracting and relaxing. Eccentric contractions consist of a longer time contracting than relaxing. Concentric contractions occur when the tension produced never exceeds the load, and the muscle does not change length. Eccentric contractions occur when the tension produced exceeds the load, and the muscle shortens. Concentric contractions occur when the muscle tension exceeds the load, and the muscle shortens. Eccentric contractions occur when the muscle tension is less than the load, and the muscle elongates. Concentric contractions consist of equal lengths of time contracting and relaxing. Eccentric contractions consist of a longer time relaxing than contracting. Concentric contractions occur when the muscle tension is less than the load, and the muscle elongates. Eccentric contractions occur when the muscle tension exceeds the load, and the muscle shortens.

Concentric contractions occur when the muscle tension exceeds the load, and the muscle shortens. Eccentric contractions occur when the muscle tension is less than the load, and the muscle elongates.

Define depolarization, and describe the events that follow it. (Module 9.5B) Depolarization is the when the inside of the cell becomes positive due to sodium ions rushing in. After depolarization, repolarization occurs when potassium ions rush out of the cell causing the inside of the cell to become negative again.Depolarization is when the inside of the cell becomes neutral due to an equal amount of sodium ions entering the cell and potassium ions leaving the cell.Depolarization is the when the inside of the cell becomes negative due to potassium ions rushing out. After depolarization, repolarization occurs when sodium ions rush into the cell causing the inside of the cell to become positive again.Depolarization is the when the inside of the cell becomes negative due to sodium ions rushing out. After depolarization, repolarization occurs when potassium ions rush into the cell causing the inside of the cell to become positive again.Depolarization is the when the inside of the cell becomes positive due to potassium ions rushing in. After depolarization, repolarization occurs when sodium ions rush out of the cell causing the inside of the cell to become negative again.

Depolarization is the when the inside of the cell becomes positive due to potassium ions rushing in. After depolarization, repolarization occurs when sodium ions rush out of the cell causing the inside of the cell to become negative again.

What is the general function of an excitable membrane? (Module 9.5C) Excitable membranes are on cells with extracellular receptors for binding chemicals. Excitable membranes allow ions to leak across ion channels. Excitable membranes permit rapid communication between different parts of a cell. Excitable membranes function in slow, endocrine cell-cell communication. Excitable membranes function when the intracellular fluid and extracellular fluid compositions match.

Excitable membranes permit rapid communication between different parts of a cell.

Compare F-actin with G-actin. (Module 9.4A) G actin is a twisted strand made up of two rows of F actin subunits where myosin heads can bind. F actin binds myosin during muscle contraction and G actin binds myosin during muscle relaxation. F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind. F actin is functional actin that contains myosin binding sites and G actin covers the binding sites on F actin to prevent actin-myosin interaction. F actin binds myosin during muscle relaxation and G actin binds myosin during muscle contraction.

F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind.

The area in the center of the A band that contains no thin filaments is the H band. Z line. M line. zone of overlap. I band.

H band.

The region of the sarcomere that always contains only thin filaments is the I band. M line. H band. A band. Z line.

I band.

Compare incomplete tetanus with wave summation. (Module 9.10A) In incomplete tetanus, the muscle generates a slightly higher maximum tension with each successive stimulus after each relaxation phase. Wave summation refers to a muscle continuously contracting with no relaxation. In incomplete tetanus, the muscle is producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to rapid numbers of action potentials occurring over a period of time. In incomplete tetanus, the muscle is producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to the addition of one twitch to another. In incomplete tetanus, the muscle is continuously contracting with no relaxation. Wave summation refers to the addition of one twitch to another. In incomplete tetanus, the muscle is continuously contracting with no relaxation. Wave summation refers to an increases length of the relaxation phase with higher degrees of tension.

In incomplete tetanus, the muscle is producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to the addition of one twitch to another.

Which of the following is not true of the muscular system? It depends upon calcitonin and parathyroid hormone levels to maintain calcium homeostasis. It depends upon the cardiovascular system to provide the hemoglobin stored in slow muscle fibers. It depends upon the nervous system to stimulate skeletal muscle tissue to contract. It depends upon the integumentary system to protect muscles. It depends upon calcium stored and released from the skeletal system.

It depends upon the cardiovascular system to provide the hemoglobin stored in slow muscle fibers.

Summarize the sliding filament theory. (Module 9.4C) It is the process that causes an action potential to travel down the T tubules into the sarcolemma. It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another. It is the theory that excitation-contraction coupling leads to muscle fiber relaxation. It is the theory that Z lines will move further from each other when the thin and thick filaments slide past each other. It is the theory that sarcomeres lengthen during the sliding of the thin and thick filaments past each other.

It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another.

How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle? It would produce uncontrolled muscle spasms. It would make the muscles more excitable.It would have little effect on skeletal muscles. It would cause flaccid paralysis (muscles are relaxed and unable to contract). It would cause spastic paralysis (muscles are contracted and unable to relax).

It would cause flaccid paralysis (muscles are relaxed and unable to contract).

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle? It would produce muscle weakness. It would make the muscles less excitable.It would cause flaccid paralysis (muscles are relaxed and unable to contract). It would cause spastic paralysis (muscles are contracted and unable to relax). It would have little effect on skeletal muscles.

It would cause spastic paralysis (muscles are contracted and unable to relax).

In a sarcomere, thick filaments are linked laterally by proteins of the M line. A band. H band. Z line. I band.

M line.

Why is there partial relaxation in graph (c)? The muscle is starting to fatigue. Maximum tension is below maximum. Stimulation intensity is fluctuating. Calcium ion release is slow.ATP reserves are cycling.

Maximum tension is below maximum.

What happens to the lactate produced by skeletal muscle during peak activity? (Module 9.13C) Most of the lactate enters the electron transport chain to produce more ATP. Most of the lactate is used by the skeletal muscle to remake creatine phosphate. Most of the lactate accumulates and causes cramps. Most of the lactate diffuses into the bloodstream and enters the liver where it is converted to pyruvate. Most of the lactate undergoes fermentation in the muscle to produce more ATP.

Most of the lactate diffuses into the bloodstream and enters the liver where it is converted to pyruvate.

Which statement about the microscopic anatomy of skeletal muscle fibers is not true? Cross striations result from the lateral alignment of thick and thin filaments. Each fiber has many nuclei.Muscle fibers are continuous from tendon to tendon. Tubular extensions of the sarcolemma penetrate the fiber transversely. Multiple myofibrils link end-to-end along length of the muscle cell.

Multiple myofibrils link end-to-end along length of the muscle cell.

When do muscle fibers produce lactate? (Module 9.12C) Muscle fibers produce lactate when ATP is abundant. Muscle fibers produce lactate when metabolizing amino acids. Muscle fibers produce lactate when the pH of the cell is acidic. Muscle fibers produce lactate when metabolizing fatty acids. Muscle fibers produce lactate when there is a lack of oxygen.

Muscle fibers produce lactate when there is a lack of oxygen.

Define muscle hypertrophy and muscle atrophy. (Module 9.15A) Muscle hypertrophy is an increase in the size of the muscle cells and muscle atrophy is a decrease in the number of muscle cells. Muscle hypertrophy is an increase in the vascularization of the muscle cells and muscle atrophy is a decrease in the vascularization of the muscle cells. Muscle hypertrophy is an increase in the size of the muscle cells and muscle atrophy is a decrease in the size of the muscle cells. Muscle hypertrophy is an increase in the number of muscle cells and muscle atrophy is a decrease in the size of the muscle cells. Muscle hypertrophy is an increase in the number of muscle cells and muscle atrophy is a decrease in the number of muscle cells.

Muscle hypertrophy is an increase in the size of the muscle cells and muscle atrophy is a decrease in the size of the muscle cells.

Define oxygen debt (excess postexercise oxygen consumption). (Module 9.13B) Oxygen debt is the sum total of oxygen molecules used during cellular metabolism. Oxygen debt is the amount of oxygen intake required to produce the ATP needed to restore the body after strenuous activity. Oxygen debt is the decrease in oxygen during active aerobic respiration. Oxygen debt is the accumulation of oxygen in tissues during anaerobic respiration. Oxygen debt is the amount of oxygen that must be returned to the lungs following strenuous exercise.

Oxygen debt is the amount of oxygen intake required to produce the ATP needed to restore the body after strenuous activity.

How is skeletal muscle recovery different after moderate activity compared to sustained activity at higher levels? (Module 9.13A) Skeletal muscle recovery after moderate activity takes several hours, whereas skeletal muscle recovery at higher levels can take about a week. Skeletal muscle recovery after moderate activity takes a few months, whereas skeletal muscle recovery at higher levels can take a few years. Skeletal muscle recovery after moderate activity takes a few hours, whereas skeletal muscle recovery at higher levels can take a day. Skeletal muscle recovery after moderate activity takes about a week, whereas skeletal muscle recovery at higher levels can take a few months. Skeletal muscle recovery after moderate activity takes about a minutes, whereas skeletal muscle recovery at higher levels can take a few hours.

Skeletal muscle recovery after moderate activity takes several hours, whereas skeletal muscle recovery at higher levels can take about a week.

Which of the following statements is incorrect? Which of the following statements is incorrect? Skeletal muscle contractions help maintain body temperature. The contractions of skeletal muscles pull on tendons and move bones of the skeleton. Skeletal muscles support the weight of some internal organs. Skeletal muscles store nutrient reserves. Skeletal muscles are responsible for the pumping action of the heart.

Skeletal muscles are responsible for the pumping action of the heart.

Describe the relationship between the number of fibers in a motor unit and the precision of body movements. (Module 9.10C) The finer and more precise the movement, the greater the number of motor neurons in the motor unit. The finer and more precise the movement, the greater the number of muscle fibers in the motor unit. The finer and more precise the movement, the thicker the muscle fibers in the motor unit. The finer and more precise the movement, the thinner the muscle fibers in the motor unit. The finer and more precise the movement, the fewer the number of muscle fibers in the motor unit.

The finer and more precise the movement, the fewer the number of muscle fibers in the motor unit.

Explain the relationship between load and speed of muscle contraction. (Module 9.11A) The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens. The greater the load on a muscle, the less time it takes for the muscle to shorten, and the less it shortens. The greater the load on a muscle, the longer it takes for the muscle to shorten, and the more it shortens. The greater the load on a muscle, the less time it takes for the muscle to shorten, and the more it shortens. There is no relationship between load and speed of muscle contraction.

The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens.

What sarcomere characteristic affects the amount of tension produced when a skeletal muscle fiber contracts? (Module 9.9A) The number of actin binding sites. The number of myosin heads. The time it takes the sarcomere to shorten. The length of the sarcomere. The amount of troponin proteins bound to actin.

The length of the sarcomere.

During anaerobic glycolysis, which of the following does not occur? ATP is produced. Pyruvate is produced. The mitochondria are required. Lactate is produced. Oxygen is not consumed.

The mitochondria are required.

What would happen if there were no AChE in the synaptic cleft? (Module 9.6C) The motor end plate would be continuously stimulated and continuous muscle contraction would occur. The motor end plate would be continuously stimulated and no muscle contraction could occur. The motor end plate would be unaffected because epinephrine not ACh stimulates the contraction of skeletal muscles. The motor end plate could not be stimulated and no muscle contraction could occur. The motor end plate could not be stimulated and continuous muscle contraction would occur.

The motor end plate would be continuously stimulated and continuous muscle contraction would occur.

Explain why the propagation of action potentials along electrically excitable membranes occurs in only one direction. (Module 9.5D) All electrically excitable membranes have two poles, a positive and a negative pole, and the action potential can only travel towards the positive pole. The repolarization period prevents it from propagating back in the direction from which it began. The stimulation of electrically excitable membranes by neurons occurs on only one side of the membrane so it will travel to the other side. The refractory period prevents it from propagating back in the direction from which it began. All electrically excitable membranes have two poles, a positive and a negative pole, and the action potential can only travel towards the negative pole.

The refractory period prevents it from propagating back in the direction from which it began.

Explain the function of sodium-potassium ion pumps. (Module 9.5A) The sodium-potassium ion pump allows facilitated diffusion of sodium during the depolarization of a muscle cell. The sodium-potassium ion pump binds acetylcholine across the synaptic cleft to generate an action potential at the sarcolemma. They generate ATP for the cell during the electron transport chain when hydrogen ions move in a process known as chemiosmosis. The sodium-potassium ion pump allows facilitated diffusion of potassium during the repolarization of a muscle cell. The sodium-potassium ion pump maintains the resting membrane potential of a cell by exporting three sodium ions out in exchange for two potassium ions entering the cell.

The sodium-potassium ion pump maintains the resting membrane potential of a cell by exporting three sodium ions out in exchange for two potassium ions entering the cell.

Why is the zone of overlap an important region of the sarcomere? (Module 9.4D) The zone of overlap is important because it is where one sarcomere ends and another sarcomere begins. The zone of overlap is important because it is where myosin filaments are anchored to and overlap titin proteins. The zone of overlap is important because it is where the troponin proteins bind acetylcholine to generate an action potential that can cause muscle contraction to occur. The zone of overlap is important because it is where actin filaments are anchored to and overlap nebulin proteins. The zone of overlap is important because it is where the myosin heads can interact with the thin filaments.

The zone of overlap is important because it is where the myosin heads can interact with the thin filaments.

What is thought to happen in a muscle during the response shown in graph (a)? It is strengthening with exercise. It is fatigued and must make repeated efforts to twitch normally.It is aged and has lost contractile proteins. There is a gradual increase in the concentration of calcium ions in the sarcoplasm. It is producing more ATP as tension increases.

There is a gradual increase in the concentration of calcium ions in the sarcoplasm.

Which of the following statements is not true about action potentials? They can travel long distances within cells. They can be generated in less than 2 msec. They occur in neurons. They end in repolarization. They can travel in two directions.

They can travel in two directions.

Define transverse tubules. (Module 9.3B) Transverse tubules are composed primarily of myosin filaments. Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum. Transverse tubules are tubular proteins that bind calcium within the sarcomeres. Transverse tubules are composed primarily of actin filaments. Transverse tubules forms a tubular network around each individual myofibril and is similar to the smooth endoplasmic reticulum of other cells.

Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum.

Can a skeletal muscle contract without shortening? Why or why not? (Module 9.11C) No, because muscles contract only when the muscle tension exceeds the load. No, because muscles can only generate tension while shortening, never during lengthening. Yes, because muscles can still contract during an isometric contraction when the muscle tension is equal to the load. No, because muscles contract only when the muscle tension is less than the load. Yes, because muscles can still contract during an isotonic contraction when the tension is at a constant level.

Yes, because muscles can still contract during an isometric contraction when the muscle tension is equal to the load.

Which of the following motor units would produce the greatest tension? a motor unit in a back muscle a motor unit in an eye muscle a motor unit in a hand muscle

a motor unit in a back muscle

Which of the following muscles would contract more forcefully? a muscle receiving 20 to 25 action potentials per second a muscle receiving 10 to 15 action potentials per second

a muscle receiving 20 to 25 action potentials per second

The skeletal muscle complex known as the triad consists of a terminal cisterna and two transverse tubules. actin, myosin, and sarcomeres. filaments, myofibrils, and muscle fibers. A bands, H bands, and I bands. a transverse tubule and two terminal cisternae.

a transverse tubule and two terminal cisternae.

Triggering of the muscle action potential occurs after the nerve action potential jumps across the neuromuscular junction. acetylcholine binds to chemically gated channels in the motor end plate membrane. acetylcholinesterase binds to receptors on the end plate. calcium ion binds to channels on the end plate. Any of these actions can produce an action potential in the muscle cell.

acetylcholine binds to chemically gated channels in the motor end plate membrane.

The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter antidiuretic hormone. acetylcholine. acetylcholinesterase. epinephrine. norepinephrine.

acetylcholine.

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is active transport of calcium into the synaptic cleft.active transport of calcium back into the sarcoplasmic reticulum. diffusion of calcium out of the cell. diffusion of calcium into the sarcoplasmic reticulum. active transport of calcium across the sarcolemma.

active transport of calcium into the synaptic cleft.active transport of calcium back into the sarcoplasmic reticulum.

Creatine phosphate can replace ATP in binding to myosin molecules during contraction.is produced by the process of anaerobic respiration. cannot transfer its phosphate group to ADP. acts as an energy reserve in muscle tissue. is only formed during strenuous exercise.

acts as an energy reserve in muscle tissue.

During the recovery period, the body's need for oxygen is increased because muscle cells are producing energy anaerobically. additional oxygen is required to restore energy reserves consumed during exercise. the individual is panting. the liver requires more oxygen to produce lactic acid. the muscles are not producing ATP.

additional oxygen is required to restore energy reserves consumed during exercise.

A resting muscle generates most of its ATP by the tricarboxylic acid cycle. glycogenolysis. hydrolysis of creatine phosphate. anaerobic respiration. aerobic metabolism of fatty acids.

aerobic metabolism of fatty acids.

Decreased blood flow to a muscle could result in all of the following except an increase in intracellular glycogen. an oxygen debt. muscle fatigue. an increase in intracellular lactate. a shift to anaerobic glycolysis.

an increase in intracellular glycogen.

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs. paralysis tetanus treppe atrophy an oxygen debt

an oxygen debt

When comparing slow fibers to fast fibers, slow fibers appear dark red. are lacking myoglobin. take less time to reach peak tension. generate much more tension. have much larger fiber diameters.

appear dark red.

What is released from the structure labeled "9"? proteins sodium acetylcholinesterase acetylcholine calcium ions

calcium ions

In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases hydrogen ions. calcium ions. sodium ions. acetylcholine. potassium ions.

calcium ions.

Which process employs exocytosis? facilitated diffusion cross-bridge formation depolarization chemical synapse antagonist binding

chemical synapse

What is the contraction in graph (d) called? twitch wave summation complete tetanus treppe incomplete tetanus

complete tetanus

When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called incomplete tetanus. complete tetanus. a twitch. wave summation. recruitment.

complete tetanus.

What physiological process occurs in the structure labeled "7"? release of acetylcholineacetylcholinesterase breakdown of acetylcholinerelease of proteins into the muscle fiber conduction of the action potential toward the triad the sliding of actin and myosin filaments

conduction of the action potential toward the triad

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for forconduction. cushioning. peristalsis. contraction .None of the answers is correct.

contraction

Calcium ions are bound to troponin during which of the following steps. contraction phase the first 2 msec following stimulation latent period recovery phase None of the answers is correct.

contraction phase

Which of the following is not a recognized function of skeletal muscle? maintain body temperature guard body entrances and exits controlled involuntarily maintain posture produce movement

controlled involuntarily

Physical evidence that supports the sliding filament theory of muscle contraction includes increased width of the I band during contraction. the I band and H band distance is constant during contraction .decreased width of the A band during contraction. decreased width of the H band during contraction. constant distance between Z lines during contraction.

decreased width of the H band during contraction.

During the ________ phase of action potential development, voltage-gated sodium channels are open. refractory depolarization repolarization threshold

depolarization

Individual muscle cells are surrounded by what connective tissue? sarcolemma endomysium myofibrils sarcomere perimysium

endomysium

The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the theperiosteum. epimysium. endomysium. perimysium. superficial fascia.

endomysium.

Muscular force can be adjusted to match increased loads by recruiting fewer motor units. increasing the frequency of action potentials in motor neurons. recruiting smaller motor units. decreasing the frequency of action potentials in motor neurons. None of the answers is correct.

increasing the frequency of action potentials in motor neurons.

Which of these would not lead to increased oxygen consumption? increased heat production lactic acidosis increased conversion of lactic acid to glucose increased aerobic respiration by muscle cells increased muscle activity

lactic acidosis

Na+ and K+ both use ________ to passively diffuse across the plasma membrane. voltage-gated channel scarrier-mediated transport exocytosis leak channels facilitated diffusion

leak channels

The muscle weakness of myasthenia gravis results from loss of acetylcholine receptors in the end-plate membrane. the motor neuron action potential being too small to shock the muscle fibers .insufficient acetylcholine release from presynaptic vesicles. excessive acetylcholinesterase that destroys the neurotransmitter. All of the answers probably contribute to the muscle weakness.

loss of acetylcholine receptors in the end-plate membrane.

Cellular membrane potential is measured in amperes. milliseconds. millivolts .micrometers. Hertz.

millivolts

Identify the structures labeled "1." glycogen mitochondria synaptic vesicle myofibril ATP

mitochondria

Which of the following is not found in the structure labeled "3"? titin actin tropomyosin mitochondria myosin

mitochondria

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes less permeable to sodium ions. more permeable to sodium ions. repolarized. less permeable to potassium ions. more permeable to calcium ions.

more permeable to sodium ions.

During activities requiring aerobic endurance, oxygen is not required. fatigue occurs in a few minutes. oxygen debts are common. most of the muscle's energy is produced in mitochondria. glycogen and glycolysis are the primary sources of reserve energy.

most of the muscle's energy is produced in mitochondria.

Receptors for acetylcholine are located on the motor end plate .synaptic cleft. transverse tubule. synaptic knob. sarcomere.

motor end plate

A single motor neuron together with all the muscle fibers it innervates is called a(n) end foot. end plate. motor unit. dermatome. myotome.

motor unit.

Neurons and ________ have electrically excitable membranes that propagate action potentials. epithelial cells dense connective tissue muscle cells proteins osteocyte

muscle cells

Interactions between actin and myosin filaments of the sarcomere are responsible for muscle contraction. muscle fatigue. the conduction of neural stimulation to the muscle fiber. muscle relaxation. the striped appearance of skeletal muscle.

muscle contraction.

What basic reactants do mitochondria absorb from the cytosol to synthesize ATP? (Module 9.12A) carbon dioxide, water, glycogen, and inorganic substrates water, lactate, GTP, and ADP oxygen, creatine phosphate, and ADP carbon dioxide, GTP, sodium and phosphate ions oxygen, ADP, phosphate ions, and organic substrates

oxygen, ADP, phosphate ions, and organic substrates

Nerves and blood vessels that service the muscle fibers are located in the connective tissues of the thesarcoplasm. sarcolemma. perimysium. myofibrils. sarcomere.

perimysium.

Of the following clinical conditions affecting skeletal muscle, which is caused by a virus? polio tetanus botulism Duchenne muscular dystrophy rigor mortis

polio

Which of the following is an ion that is more concentrated inside the cell than outside? chloride calcium sodium hydrogen potassium

potassium

The advantage of having many nuclei in a skeletal muscle fiber is the ability to produce more ATP with little oxygen. produce large amounts of the muscle proteins needed for muscle contraction. contract. All of the answers are correct.

produce large amounts of the muscle proteins needed for muscle contraction.

The increase in muscle tension that is produced by increasing the number of active motor units is called treppe. complete tetanus. recruitment. incomplete tetanus. wave summation.

recruitment.

Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to increased levels of testosterone. high amounts of oxygen. prolonged periods of inactivity. repeated, exhaustive stimulation. sustained low levels of muscle activity.

repeated, exhaustive stimulation.

If potassium channels were blocked, the ________ phase of the action potential would not occur normally. .refractory depolarization repolarization threshold

repolarization

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as oxygen debt .tetany. rigor mortis .depolarization. treppe.

rigor mortis

The plasma membrane of skeletal muscle is called the thesarcomere. sarcosome. sarcoplasm. sarcoplasmic reticulum. sarcolemma.

sarcolemma.

The repeating contractile unit of a skeletal muscle fiber is the sarcomere. myofibril. myofilament. sarcoplasmic reticulum. sarcolemma.

sarcomere.

Excitation-contraction coupling is the transfer of ACh into the synaptic cleft. sliding of thin filaments past thick filaments during muscle fiber contraction. refractory period of an action potential. threshold period of an action potential. sequence of processes that links the action potential to contraction.

sequence of processes that links the action potential to contraction.

Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber strengthens. shortens. weakens.lengthens .There is insufficient information to determine the answer.

shortens.

Which muscle types are voluntary, and which are involuntary? (Module 9.1B) skeletal muscle is voluntary, and cardiac and smooth muscles are involuntary skeletal and smooth muscles are voluntary, and cardiac muscle is involuntaryskeletal and cardiac muscles are voluntary, and smooth muscle is involuntarycardiac and smooth muscles are voluntary, and skeletal muscle is involuntarysmooth muscle is voluntary, and cardiac and smooth muscles are involuntary

skeletal muscle is voluntary, and cardiac and smooth muscles are involuntary

The structural explanation of how a muscle fiber contracts is called the sliding filament theory .cross-bridge connection .myosin spiral theory. active site rule. thin filament theory.

sliding filament theory

The type of muscle fiber that is most resistant to fatigue is the ________ fiber. high-density slow anaerobic fast intermediate

slow

Which type of muscle fiber predominates in the leg muscles of endurance athletes, such as long-distance runners? (Module 9.14C) fast fibers slow fibers intermediate fibers

slow fibers

Which of the following best describes the sarcoplasmic reticulum? thin filaments are anchored here repeating unit of striated myofibrils storage and release site for calcium ions largely made of myosin molecules protein that accounts for elasticity of resting muscle

storage and release site for calcium ions

Which of the following best describes the term titin? repeating unit of striated myofibrils largely made of myosin molecules storage site for calcium ions substance that accounts for elasticity of resting muscle where thin filaments are anchored

substance that accounts for elasticity of resting muscle

The narrow space between the synaptic terminal and the muscle fiber is the M line. motor end plate .synaptic knob. synaptic cleft .motor unit.

synaptic cleft

At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a tenosynovium. sheath .ligament. tendon. satellite cell.

tendon.

The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n) ligament. tendon. fascicle. myofibril. epimysium.

tendon.

Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass? parathyroid hormone calcitonin thyroid hormone testosterone epinephrine

testosterone

Which of the following is greater? the concentration of calcium ion in the sarcoplasmic reticulum of a resting muscle the concentration of calcium ion in the sarcoplasm of a resting muscle

the concentration of calcium ion in the sarcoplasmic reticulum of a resting muscle

Membrane potential is the electrical gradient of a cell. the site of signal transfer between two cells. the period when the membrane cannot respond to another stimulus. a chemical signal that has not yet bound to a receptor. a cell's capacity to respond to a chemical signal.

the electrical gradient of a cell.

The Na+/K+ ion pump is responsible for the sodium/potassium concentration gradients constant. transferring messages from enzyme-linked receptors to the cell nucleus. diffusing chloride across the plasma membrane. amplifying signals using ATP. initiating action potentials.

the sodium/potassium concentration gradients constant.

Which of the following become connected by myosin cross-bridges during muscle contraction? Z disks and actin filaments thin filaments and T tubules thick filaments and T tubules thick filaments and titin filaments thin filaments and thick filaments

thin filaments and thick filaments

Which of the following proteins is not found as a part of thin filaments? troponin tropomyosin titin actin nebulin

titin

The action potential is conducted into a skeletal muscle fiber by triads. transverse tubules. neuromuscular junctions. motor end plates. sarcoplasmic reticulum.

transverse tubules.

The complex of a transverse tubule and two adjacent terminal cisternae is known as a(n) sarcomere. free head. triad. zone of overlap. M line.

triad.

At rest, active sites on the actin are blocked by troponin molecules. calcium ions. ATP molecules. myosin molecules. tropomyosin molecules.

tropomyosin molecules.

When calcium ion binds to troponin, tropomyosin moves into the groove between the helical actin strands .active sites on the myosin are exposed. myosin shortens. troponin shifts to expose the active sites on actin. muscle relaxation occurs.

tropomyosin moves into the groove between the helical actin strands

At rest, the tropomyosin molecule is held in place by troponin molecules. ATP molecules .calcium ions. myosin molecules. actin molecules.

troponin molecules.