BIO 114 Chapter 9
Which of the following is the dark band seen on myofibrils? - H Band - Z Line - I Band - A Band
A Band
What causes the myosin head to release its attachment to actin? - The troponin-tropomyosin complex causes the myosin head to separate from the actin. - Once the power stroke occurs, the myosin separates automatically from the actin. - A new ATP molecule binds to the myosin head. - Calcium ions cause the separation of the myosin head from the actin.
A new ATP molecule binds to the myosin head
The thin filaments consist of ___________.
A pair of F-actin molecules twisted together
During __________, the muscle fiber is rapidly and continuously being stimulated and is never allowed to relax completely. - treppe - complete tetanus - incomplete tetanus - summation
Complete tetanus
What provides ATP for the first 15 seconds of a muscle contraction? - Anaerobic glycolysis - Glycogen - Aerobic metabolism - Creatine phosphate
Creatine phosphate
The length of a sarcomere determines the degree of tension produced. For optimal contraction, the ideal range of sarcomere length is 75 percent to 130 percent of its normal length. This is because at this range, there is a maximal number of _______ that can be formed during contraction. - Myosin - Cross-bridges - Actin - Titin
Cross-bridges
Which of the following would NOT be an effective source of energy for muscle contraction? - Glycogen - Creatine phosphate - DNA - ATP
DNA
After contraction, a muscle fiber returns to its original length because of __________. - elastic forces and the movement of opposing muscles - involvement of all the sarcomeres along the myofibrils - an active mechanism for fiber elongation - the tension produced by the initial length of the muscle fiber
Elastic forces and the movement of opposing muscles
The connective tissue layer that surrounds a single muscle fiber and joins it to another muscle fibers is _________?
Endomysium
Which connective tissue layer wraps around the entire muscle?
Epimysium
Nerves and blood vessels are contained within the connective tissues of the __________.
Epimysium, perimysium, and endomysium
The perimysium surrounds a bundle of muscle fibers called a __________.
Fascile
Which of the muscle fiber types is best adapted for a rapid contraction but fatigues easily? - Slow fibers - Fast fibers - Tight fibers - Intermediate fibers
Fast fibers
Voluntary control over swallowing, defecation, and urination is provided by muscles that __________.
Guard entrances and exists
Which of the following is an example of an isometric contraction? - Picking up a toddler who is sitting on the floor - Holding a heavy stack of books above the ground - Flexing the biceps muscle while holding a 10-pound weight - Walking
Holding a heavy stack of books above the ground
A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in __________. - incomplete tetanus - recruitment - treppe - complete tetanus
Incomplete tetanus
What is the effect of acetylcholine on the motor end plate of the muscle cell membrane? - Allowing Ca2+ to enter through the membrane of the motor end plate. - Opening channels and acetylcholine entering the cell through the motor end plate - Increasing the permeability to Na+, causing Na+ to diffuse into the muscle cell - Allowing K+ to enter the synaptic cleft through the motor end plate membrane.
Increasing the permeability to Na+, causing Na+ to diffuse into the muscle cell
The process of complete tetanus is reached by __________. - decreasing the concentration of calcium ions in the cytoplasm - increasing the rate of stimulation until the relaxation phase is completely eliminated - activating additional motor units - applying a second stimulus before the relaxation phase has ended
Increasing the rate of stimulation until the relaxation phase is completely eliminated
Pushing both hands against a nonmoving wall represents which type of muscle contraction? - Isometric - Isotonic - Eccentric - Concentric
Isometric
How does the release of calcium ions from the terminal cisternae initiate contraction? - It triggers the binding of myosin to actin. - It causes ATP to release energy. - It causes the myosin head to pull the actin toward the M line. - It causes troponin to attach to the actin.
It triggers the binding of myosin to actin
Which structure in a muscle fiber or muscle cell is continuous with the sarcolemma and carries the signal to contract deep into the muscle cells?
T Tubules
The connective tissue fibers of the epimysium, perimysium, and endomysium extend beyond the skeletal muscle cells to form a bundle of connective tissue that joins the muscle cells to a bone. This bundle is called a(n) ?
Tendon
The transmission of an action potential along the T tubules stimulates the release of calcium from which structure in the sarcomere?
Terminal cisterna
What structures make up a triad?
Two terminal cisternae and a T tubule
When would we use the contractile proteins in our skeletal muscle cells to provide energy?
When our diet contains too few proteins or calories
Which of the following has been correlated with muscle fatigue? - an increase in metabolic reserves within the muscle fibers - an increase in pH within the muscle fibers, which affects storage of glycogen - an increase in muscle performance resulting from an increased pain threshold - a decline in pH within the muscle, which alters enzyme activities
a decline in pH within the muscle, which alters enzyme activities
A single stimulation-contraction-relaxation sequence in a muscle fiber is known as ________. - a neuro-muscular junction - a motor unit - an action potential - a twitch
a twitch
The thick filaments consist of _______?
about 300 myosin molecules twisted around one another
The sliding of _________ over _______ causes shortening of skeletal muscle fibers.
actin; myosin
As a result of physical inactivity, muscle cell and myofibrils will be reduced in size and number, respectively. This condition is known as __________. - trophy - hyperplasia - atrophy - hypertrophy
atrophy
Mitochondrial activities are relatively efficient, but their rate of ATP generation is limited by the __________. - availability of oxygen - presence of creatine-phosphate - availability of carbon dioxide and water - energy demands of other organelles
availability of oxygen
The length of a sarcomere determines the degree of tension produced. For optimal contraction, the ideal range of sarcomere length is 75 percent to 130 percent of its normal length. This is because at this range, there is a maximal number of _______ that can be formed during contraction. - titin - actin - cross-bridges - myosin
cross-bridges
In an isotonic contraction, __________. - tension in the muscle varies as the muscle shortens - cross-bridges must produce enough tension to exceed the load to be moved - tension in the muscle decreases as the resistance increases - muscle length does not change as a result of the resistance
cross-bridges must produce enough tension to exceed the load to be moved
Which of the following produces ATP from glucose anaerobically? - aerobic metabolism - TCA cycle - creatine phosphate - glycolysis
glycolysis
Inherited disorders that produce progressive muscle weakness and deterioration within muscles are called ______________. - RICE - fibromyalgia - botulism - muscular dystrophies
muscular dystrophies
One of the distinct features of the skeletal muscle fibers is that they are multinucleated. The multinucleation is the result of the fusion of embryonic cells called __________.
myoblasts
Presence of _______ in the sarcoplasm provides a ready supply of oxygen for aerobic respiration in muscle tissue. - creatine phosphate - hemoglobin - lactic acid - myoglobin
myoglobin
The regulatory protein responsible for elasticity of skeletal muscles is _______.
titin
What happens in the muscle fiber during the Cori cycle? - Glycogen is catabolized to produce glucose for energy. - Lactic acid is shuttled to the liver and glucose is shuttled back to the muscle fiber from the liver. - Creatine phosphate is consumed. - Oxygen deficiency slows down mitochondrial activity.
Lactic acid is shuttled to the liver and glucose is shuttled back to the muscle fiber from the liver.
Why is control over leg muscles LESS precise than control over the muscles of the eye? - Many muscle fibers in the legs are controlled by many motor neurons. - Many muscle fibers in the legs are controlled by a single motor neuron. - Single muscle fibers in the legs are controlled by many motor neurons. - A single muscle fiber in a leg is controlled by a single motor neuron.
Many muscle fibers in the legs are controlled by a single motor neuron.
All the muscle fibers and the single motor neuron that innervates them are called a __________. - fascicle - treppe - motor unit - myofibril
Motor unit
Skeletal muscles develop from the conjoining of a group of embryonic cells knows as _______.
Myoblasts
Which of the following is NOT found in a thin filament?
Myosin
Extensive blood vessels, mitochondria, and myoglobin are found in the greatest concentration in __________. - intermediate fibers - fast fibers - type II fibers - slow fibers
slow fibers
The type of skeletal muscle fiber best suited for endurance-type activities is __________. - All three fiber types are suited to endurance-type activity. - intermediate fibers - fast fibers - slow fibers
slow fibers
_______ is required to detach cross-bridges and reactivate the myosin head. - Calcium - Actin - Myosin - ATP
ATP
The neurotransmitter required to trigger skeletal muscle contraction is __________. - Myosin - Calcium - Acetycholine (ACh) - Adenosine triphosphate (ATP)
Acetycholine (ACh)
What are the two mechanisms used to generate ATP from glucose? - ADP and creatine phosphate - None of the listed responses is correct. - Aerobic respiration and glycolysis - Cytoplasm and mitochondria
Aerobic respiration and glycolysis
What allows the contraction cycle to repeat so that shortening of the sarcomere happens? - The active site on actin remains exposed. - Calcium levels remain high in the sarcomere. - All of the choices are correct. -ATP is continuously supplied by the mitochondria.
All of the choices are correct
What can happen when multiple stimuli are applied to a muscle fiber before it completely relaxes and tension production is gradually increasing? - Complete tetanus - Incomplete tetanus - All of the listed answers are correct - Wave summation
All of the listed answers are correct
What can happen when multiple stimuli are applied to a muscle fiber before it completely relaxes and tension production is gradually increasing? - Incomplete tetanus - Wave summation - Complete tetanus - All of the listed answers are correct.
All of the listed answers are correct
Which of the following may cause muscle atrophy? - Paralysis - Wearing a cast on a broken limb - All of the listed responses are correct. - A lack of regular stimulation of muscle fibers
All of the listed responses are correct.
Which of the following is NOT found in the endomysium? - Capillary Networks - Nerve Fibers - Myosatellite Cells - All of these are present in the endomysium
All of these are present in the endomysium
A blending of epimysium, perimysium, and endomysium that forms a broad sheet at the end of a muscle is known as __________.
An aponeurosis
The amount of tension produced by an individual muscle fiber ultimately depends on the __________. - number of pivoting cross-bridges - all-or-none principle - the muscle's latent period - number of calcium ions released
Number of pivoting cross-bridges
The H band contains which structures?
Only myosin in the thick filaments
Skeletal muscles generate maximum tension when the maximum number of cross-bridges can form in the zone of __________. - Z line - I band - H zone - Overlap
Overlap
The connective tissue layer that surrounds a bundle of skeletal muscle fibers is called __________.
Perimysium
When lifting a heavy weight, more motor neurons are called into action to overcome the weight by creating a greater tension. This phenomenon is known as _________. - isometric contraction - motor unit - muscle tone - recruitment
Recruitment
Which type of tissue is responsible for holding your head upright while you are reading this question?
Skeletal Muscle Tissue
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth
Marathon runners rely on which muscle fiber type for endurance? - Fast fibers - Intermediate fibers - Tight fibers - Slow fibers
Slow fibers
Which of the following activities describes an isotonic eccentric contraction? - Working on the core muscles by getting into the plank position. - Pushing against a closed door. - Picking up a book. - Slowly lowering a book out in front of you with the arm extended.
Slowly lowering a book out in front of you with the arm extended.
What must bind to troponin in order to expose the active sites on actin?
Calcium ions
The first step in the contraction cycle in skeletal or cardiac muscles is when ______ binds to ________. - calcium; calmodulin - sodium; troponin - calcium; troponin - calcium; tropomyosin
Calcium; troponin
Depolarization of the skeletal muscles at the NMJ occurs as a result of acetylcholinebinding and opening the _____________. - Chemically gated chloride channels - Chemically gated calcium channels - Chemically gated potassium channels - Chemically gated sodium channels
Chemically gated sodium channels
The repeating functional units seen in the myofibrils are __________.
Sacromeres
Where is the site of calcium storage in the skeletal muscle fibers?
Sacroplasmic reticulum
Myofibrils are formed as a result of repeating functional units called _________.
Sarcomeres
Which type of muscle tissue causes contraction of the urinary bladder, forcing urine out of the body?
Smooth muscle tissue
What is happening during the contraction phase of a single twitch? - The membranes of the terminal cisternae are becoming permeable to calcium ions. - Calcium is being released from the terminal cisternae. - The action potential is moving along the sarcolemma and down the T-tubules. - The muscle is producing tension.
The muscle is producing tension
What is happening during the contraction phase of a single twitch? - The muscle is producing tension. - Calcium is being released from the terminal cisternae. - The action potential is moving along the sarcolemma and down the T-tubules. - The membranes of the terminal cisternae are becoming permeable to calcium ions.
The muscle is producing tension
What structure below is part of the crossbridge?
The myosin head
What causes the myosin head to reenergize itself once the power stroke has occurred? - The binding site on actin is still uncovered. - More calcium is released into the sarcomere. - The mitochondria release more ATP. - The myosin head splits a fresh ATP molecule.
The myosin head splits a fresh ATP molecule
What happens during the power stroke? - The thin filaments slide toward the M line. - ATP releases energy to the myosin head. - ATP causes the myosin head to release from binding to the actin. - Myosin heads attach to the actin.
The thin filaments slide toward the M line
The regulatory protein responsible for binding to calcium for contraction to proceed is _____.
Troponin
Excitation-contraction coupling forms the link between __________. - the release of Ca2+ and the binding of troponin to Ca2+ - depolarization and repolarization - the neuromuscular junction and the sarcoplasmic reticulum - electrical activity in the sarcolemma and the initiation of a contraction
electrical activity in the sarcolemma and the initiation of a contraction
During the recovery period, the body's oxygen demand is __________. - unchanged - elevated above normal resting levels - an irrelevant factor - decreased below normal resting levels
elevated above normal resting levels
What is the type of contraction in which the muscle does not change length and the contraction does not produce tension that exceeds the load? - concentric - tetanic - isotonic - isometric
isometric
During anaerobic muscle metabolism, _______ is produced as the end product of glycolysis. - fatty acids - glucose - lactate - amino acids
lactate
When glycolysis produces pyruvic acid faster than it can be used by the mitochondria, the pyruvic acid is converted to __________, which lowers the pH of body fluids. - ATP - creatine phosphate - fatty acid - lactic acid
lactic acid
Heat released from contracting muscles functions to __________.
maintain body temperature
