Anatomy - Muscle Tissue Test
Which of these would not lead to increased oxygen consumption?
lactic acidosis
Excitation-contraction coupling is the
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
shortens
Which muscle types are voluntary, and which 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
The narrow space between the synaptic terminal and the muscle fiber is the
synaptic cleft
At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a
tendon
The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called
tendon
Within a resting skeletal muscle fiber, where is the greatest concentration of Ca2+
terminal cisternae of the sarcoplasmic reticulum
Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?
testosterone
How is skeletal muscle recovery different after moderate activity compared to sustained activity at higher levels?
After moderate activity, it may take several hours for a muscle fiber to recover. After sustained activity at higher levels, complete recovery can take a week.
dentify three sources of stored energy utilized by muscle fibers. (
ATP, creatine phosphate, and glycogen
Which of the following is found in the structure labeled "3"?
All: action, myosin, titin, & tropomyosin // not found - mitochondria
When does lactation in muscles occur. lactic acid
Muscle fibers produce lactate when there is a lack of oxygen.
Define muscle hypertrophy and muscle atrophy.
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 number of muscle cells and muscle atrophy is a decrease in the number of muscle cells. (x) 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 vascularization of the muscle cells and muscle atrophy is a decrease in the vascularization of the muscle cells.
Which of the following muscles would contract more forcefully?
a muscle receiving 20 to 25 action potentials per second
The skeletal muscle complex known as the triad consists of
a transverse tubule and two terminal cisternae.
The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the
endomysium
The dense layer of connective tissue that surrounds an entire skeletal muscle is the
epymysium
The synchronous contraction of a single motor unit is known as a(n)
fasciculation.
Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of
fast fibers
During the Cori cycle, in the liver,
glucose is produced from lactate.
Muscle fibers differ from "typical cells" in that muscle fibers
have many nuclei.
Each skeletal muscle fiber contains ________ myofibrils.
hundreds to thousands
If the membrane potential of a neuron is -80 mV, it is
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
The type of contraction in which the muscle fibers do not shorten is called
isometric
How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?
it would cause flaccid paralysis (muscles are relaxed and unable to contract)
What molecule supplies the energy for a muscle fiber contraction?
ATP
Muscular force can be adjusted to match increased loads by
(X) increasing the frequency of action potentials in motor neurons. recruiting smaller motor units. recruiting fewer motor units. decreasing the frequency of action potentials in motor neurons. (x) None of these answers are correct. WRONG ANSWER
Which of the following statements is/are not true regarding human muscles?
(x) A) All human muscles have both slow and fast fibers. B) Fast fibers are found in the calf muscles. C) Eye and hand muscles are composed of fast fibers. D) Back muscles are mostly composed of endurance fibers. E) both C and D - ANSWER
Compare incomplete tetanus with wave summation.
(x) 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 an increases length of the relaxation phase with higher degrees of tension. 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 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.
Which statement about the microscopic anatomy of skeletal muscle fibers is not true?
(x) Multiple myofibrils link end-to-end along length of the muscle cell. 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.
Which of the following statements is incorrect?
(x) Skeletal muscles are responsible for the pumping action of the heart. The contractions of skeletal muscles pull on tendons and move bones of the skeleton. Skeletal muscles store nutrient reserves. Skeletal muscle contractions help maintain body temperature. Skeletal muscles support the weight of some internal organs.
What sarcomere characteristic affects the amount of tension produced when a skeletal muscle fiber contracts?
(x) The number of myosin heads. WRONG ANSWER (x) The length of the sarcomere. The number of actin binding sites. The time it takes the sarcomere to shorten. The amount of troponin proteins bound to actin.
Which process employs exocytosis?
(x) facilitated diffusion ---> chemical synapse
Muscular force can be adjusted to match different loads by
-recruiting more motor units - varying the frequency of action potentials in motor neurons -recruiting larger motor units (X) A, B, and C -None of the above muscle contraction is all-or-none.
At peak levels of muscle exertion, the mitochondria can supply ________ of the energy required by the muscle.
1/3 of the energy
Where is ATP is consumed?
3 - thick filaments
The region of the sarcomere containing the thick and thin filaments is the
A band (not z line)
define motor unit.
A motor unit is a motor neuron and all the muscle fibers that it controls.
Where are the myosin molecules located?
CHECK MUSCLE DIAGRAM
Which statement about excitation-contraction coupling is incorrect?
Calcium ion is released from the transverse tubule.
What causes calcium to be released from the sarcoplasmic reticulum?
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.
Compared with slow fibers, fast fibers have a larger diameter, larger glycogen reserves, less myoglobin, and relatively fewer mitochondria.
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 larger diameter, larger glycogen reserves, less myoglobin, and relatively fewer mitochondria.
Compare concentric and eccentric contractions.
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.
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.
Which of the following statements is/are not true regarding human muscles?
Eye muscles are composed entirely of fast fibers. (x) Fast fibers are high in myoglobin. Slow fibers are abundant in the back muscles. Slow fibers are abundant in the calf muscles. Most have both slow and fast fibers.
Compare F-actin with G-actin.
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 contraction and G actin binds myosin during muscle relaxation. F actin binds myosin during muscle relaxation and G actin binds myosin during muscle contraction. (x) F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind. G actin is a twisted strand made up of two rows of F actin subunits where myosin heads can bind.
Summarize the sliding filament theory.
It is the theory that sarcomeres lengthen during the sliding of the thin and thick filaments past each other. X ---> It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another.
How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
It would cause spastic paralysis (muscles are contracted and unable to relax)
Why is there partial relaxation in graph (c)?
Maximum tension is below maximum
are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.
Myosatellite cells
graph c
Nerve stimulation frequency is below maximum.
Name the three types of muscle tissue, identify where they are found, and list their functions.
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.
Which of the following statements is incorrect?
Skeletal muscles store nutrient reserves. The contractions of skeletal muscles pull on tendons and move bones of the skeleton. (x) Skeletal muscles are responsible for the pumping action of the heart. Skeletal muscle contractions help maintain body temperature. Skeletal muscles support the weight of some internal organs.
Explain why the propagation of action potentials along electrically excitable membranes occurs in only one direction.
The action potential moves in only one direction because when one region of an axon is depolarized • The region of the axon in front of it is resting and ready to depolarize o So the action potential can spread in this direction • The region of the axon behind has just finished depolarizing so it is still REFRACTORY. o So the action potential cannot spread in this direction.
Describe the connective tissue layers associated with skeletal muscle tissue.
The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers.
Describe the relationship between the number of fibers in a motor unit and the precision of body movements.
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.
The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens.
Explain two key concepts of the sarcomere length-tension relationship.
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.
During anaerobic glycolysis, which of the following does not occur?
The mitochondria are required. (x) Pyruvate is produced. ATP is produced. Oxygen is not consumed. Lactate is produced.
What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle fiber?
The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm.
Explain why the propagation of action potentials along electrically excitable membranes occurs in only one direction.
The refractory period prevents it from propagating back in the direction from which it began.
Why is the zone of overlap an important region of the sarcomere?
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 a graph (a)?
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 be generated in less than 2 msec. They end in repolarization. (x) They can travel in two directions. They can travel long distances within cells. They occur in neurons.
Define transverse tubules
Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum.
What basic reactants do mitochondria absorb from the cytosol to synthesize ATP?
What basic reactants do mitochondria absorb from the cytosol to synthesize ATP? (Module 9.12A) (x) oxygen, ADP, phosphate ions, and organic substrates carbon dioxide, GTP, sodium and phosphate ions carbon dioxide, water, glycogen, and inorganic substrates oxygen, creatine phosphate, and ADP water, lactate, GTP, and ADP
What happens to the lactate produced by skeletal muscle during peak activity?
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 undergoes fermentation in the muscle to produce more ATP. Most of the lactate accumulates and causes cramps. Most of the lactate is used by the skeletal muscle to remake creatine phosphate. (x) Most of the lactate diffuses into the bloodstream and enters the liver where it is converted to pyruvate.
Which of the following is greater?
Which of the following is greater? (x) 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
Which of the following is not true of the muscular system?
Which of the following is not true of the muscular system? It depends upon the integumentary system to protect muscles. (x) It depends upon the cardiovascular system to provide the hemoglobin stored in slow muscle fibers. It depends upon calcitonin and parathyroid hormone levels to maintain calcium homeostasis. It depends upon calcium stored and released from the skeletal system. It depends upon the nervous system to stimulate skeletal muscle tissue to contract.
Can a skeletal muscle contract without shortening? Why or why not?
Yes, because muscles can still contract during an isometric contraction when the muscle tension is equal to the load.
Membrane potential is
a cell's capacity to respond to a chemical signal. X ---> 1) the concentration of ions on the inside and outside of the cell; 2) the permeability of the cell membrane to those ions (i.e., ion conductance) through specific ion channels; and 3) by the activity of electrogenic pumps --> the electrical gradient of a cell. ANSWER
The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter
acetochoyne
the cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter
acetylcholine
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium back into the sarcoplasmic reticulum.
During the recovery period, the body's need for oxygen is increased because
additional oxygen is required to restore energy reserves consumed during exercise.
A resting muscle generates most of its ATP by
aerobic metabolism of fatty acids
When comparing slow fibers to fast fibers, slow fibers
appear dark red
When comparing slow fibers to fast fibers, slow fibers
are rich in the red protein myoglobin, take about three times as long to reach peak tension, have much smaller fiber diameters, and generate much less tension
What physiological process occurs in the structure labeled "7"?
conduction of the action potential toward the triad
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases
calcium ions
creatine phosphate
can replace ATP in binding to myosin molecules during contraction. is only formed during strenuous exercise. cannot transfer its phosphate group to ADP. is produced by the process of anaerobic respiration. (x) acts as an energy reserve in muscle tissue.
Na+ and K+ both use ________ to passively diffuse across the plasma membrane.
carrier-mediated transport X ---> voltage gated channels x ----> leak channels
What is the contraction in graph (d) called?
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
complete tetanus
The advantage of having many nuclei in a skeletal muscle fiber is the ability to
contract. produce more ATP with little oxygen. store extra DNA for metabolism. (x) produce large amounts of the muscle proteins needed for muscle contraction. All of the answers are correct.
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for
contraction
Which of the following is not a recognized function of skeletal muscle?
controlled involuntarily
Physical evidence that supports the sliding filament theory of muscle contraction includes
decreased width of the H band during contraction.
Calcium ions are bound to troponin during which of the following steps.
latent period (x) contraction phase recovery phase the first 2 msec following stimulation None of these answers are correct.
The muscle weakness of myasthenia gravis results from
loss of acetylcholine receptors in the end-plate membrane.
In a sarcomere, thick filaments are linked laterally by proteins of the
m line
The Na+/K+ ion pump is responsible for
maintaining the sodium/potassium concentration gradients constant.
in an isotonic contraction
many twitches fuse into one. flexion is produced. tension rises and falls but the muscle length is constant. the peak tension is less than the load. muscle tension exceeds the load and the muscle lifts the load.
Cellular membrane potential is measured in
millivolts
identify the structure where atp is produced
mitochondria
During activities requiring aerobic endurance,
most of the muscle's energy is produced in mitochondria.
A single motor neuron together with all the muscle fibers it innervates is called a(n)
motor unit
Which of the following motor units would produce the greatest tension?
motor unit in back muscle
Neurons and ________ have electrically excitable membranes that propagate action potentials.
muscle cells
Interactions between actin and myosin filaments of the sarcomere are responsible for
muscle contraction
Decreased blood flow to a muscle could result in all of the following except
muscle fatigue. a shift to anaerobic glycolysis. (x) an increase in intracellular glycogen. an increase in intracellular lactate. an oxygen debt.
In which of the following would the motor units have the fewest muscle fibers?
muscles that control the eyes
To produce a contraction similar to the one in graph (b), the muscle
must be stimulated again before it has relaxed from the previous stimulation
After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.
oxygen debt
Skeletal muscle fibers are formed from embryonic cells called
myoblasts
are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.
myosatellite
Cross-bridges are portions of
myosin
Name the proteins that make up a thick filament
myosin and titin
Which of the following proteins is not found as a part of thin filaments?
nebulin (x) titin troponin tropomyosin actin
Each skeletal muscle fiber is controlled by a motor neuron at a single
neuromuscular junction.
Communication between axons and muscle fibers occurs at specialized synapses called
neuromuscular junctions
Nerves and blood vessels that service the muscle fibers are located in the connective tissues of the
perimysium
Which of the following is not a type of motor fiber?
pink-fast twitch white-fast twitch red-slow twitch (x) white-slow twitch type I
Which of the following is an ion that is more concentrated inside the cell than outside
potassium
If potassium channels were blocked, the ________ phase of the action potential would not occur normally.
repolarization
During the ________ phase of action potential development, voltage-gated sodium channels are open.
repolarization X ---->depolarization
Of the following clinical conditions affecting skeletal muscle, which is caused by a virus?
rigor mortis botulism (x) polio tetanus Duchenne muscular dystrophy
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
rigor mortis.
The repeating contractile unit of a skeletal muscle fiber is the
sacromere
The plasma membrane of skeletal muscle is called the
sarcolemma
The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
slow twitch
Which type of muscle fiber predominates in the leg muscles of endurance athletes, such as long-distance runners?
slow twitch
Which of the following best describes the sarcoplasmic reticulum?
storage and release site for calcium ions
Which of the following best describes the term "Z line"?
storage site for calcium ions largely made of myosin molecules repeating unit of striated myofibrils protein that accounts for elasticity of resting muscle (x) where thin filaments are anchored
Which of the following best describes the term titin?
substance that accounts for elasticity of resting muscle
Which of the following acts as an ATPase during the contraction cycle of muscle
the head portion of the myosin molecule
Which of the following become connected by myosin cross-bridges during muscle contraction?
thin filaments and thick filaments
The skeletal muscle complex known as the triad consists of
transverse tubule and terminal cisternae
The complex of a transverse tubule and two adjacent terminal cisternae is known as a(
triad
When calcium ion binds to troponin,
tropomyosin moves into the groove between the helical actin strands.
At rest, the tropomyosin molecule is held in place by
troponin molecules
The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)
twitch
Each thin filament consists of
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?
wave summation.
