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