Chpt 9 Muscle/Muscle Fibers

A smooth, sustained contraction from rapid stimulation is called ____.

Tetanus

In the synaptic cleft of a neuromuscular junction, and enzyme called _____ is always present.

Acetylcholinesterase

Both actin and myosin are found in the ___. A) A band B) Z discs C) I band D) Myosin

A) A band -Following the I-band is the A-band (for anisotropic). Named for their properties under a polarizing microscope.

The myosin filaments are located in the ___. A) A band B) Z discs C) I band D) Myosin

A) A band -Myosin filaments are bipolar and extend throughout the A-band. They are crosslinked at the centre by the M-band.

25 Meter Swim A) Anaerobic Pathway B) Direct Phosphorylation C) Aerobic Pathway

A) Anaerobic Pathway

Activate synaptic vesicles in axon terminals. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

A) Calcium ions -Calcium is essential for living organisms, particularly in cell physiology, where movement of the calcium ion Ca2+ into and out of the cytoplasm functions as a signal for many cellular processes.

Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

A) Calcium ions -Calcium is essential for living organisms, particularly in cell physiology, where movement of the calcium ion Ca2+ into and out of the cytoplasm functions as a signal for many cellular processes.

A relatively high percentage are found in successful marathon runners. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

A) Slow (oxidative), fatigue-resistant fibers

Abundant in muscles used to maintain posture. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

A) Slow (oxidative), fatigue-resistant fibers

Depends on oxygen delivery and aerobic mechanisms. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

A) Slow (oxidative), fatigue-resistant fibers

Red fibers, the smallest of the fiber types. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

A) Slow (oxidative), fatigue-resistant fibers

Continued sustained smooth contraction due to rapid stimulation. A) Tetanus B) Wave summation C) Muscle Tone D) Multiple motor unit summation E) Maximal stimulus

A) Tetanus -tetan = rigid -A state of continuous muscular contraction, especially when induced artificially by rapidly repeated stimuli.

Most skeletal muscle contain ___. A) a mixture of fiber types B) a prejdominance of fast oxidative fibers C) a predominance of slow oxidative fibers D) muscle fibers of the same type

A) a mixture of fiber types

Immediately following the arival of the stimulus at a skeletal muscle cell there is a short period called the ___ period during which the events of excitation-contraction coupling occur. A) latent B) relaxation C) refractory D) contraction

A) latent -Latent period - the first few millaseconds following stimulation when excitation-contraction coupling is occuring.

Which muscle cells have the greatest ability to regenerate? A) smooth B) skeletal C) no muscle can regenerate D) cardiac

A) smooth

Creatine phosphate functions in themuscle cell by ___. A) storing energy that will be transferred to ADP to resynthesize ATP B) inducing a conformational change in the myofilaments C) forming a chemical compound with actin D) forming a temporary chemical compound with myosin

A) storing energy that will be transferred to ADP to resynthesize ATP

What does excess postexercise oxygen consumption/deficit represent? A) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amound actually used. B) the amount of oxygen taken into the body immediatly after the exertion C) the amount of oxygen needed for aerobic activity to accomplish the same amount of work D) the amount of oxygen equal to the oxygen already used

A) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amound actually used.

Weight Lifting A) Anaerobic Pathway B) Direct Phosphorylation C) Aerobic Pathway

B) Direct Phosphorylation

Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

B) Fast (oxidative or glycolytic), fatigable fibers

Contain abundant amounts of glycogen. A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers

B) Fast (oxidative or glycolytic), fatigable fibers -glycogen - one form in which body fuel is stored. -Stored primarily in liver and broken down into glucose when needed by the body.

Diffusion across the cell membrane results in depolarization. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

B) Sodium Ions -Like the plasma membranes of all celss, a resting sarcolemma is polarized. There is pltential difference across the membrane and the inside is negative relative to the outer membrane face.

The situation in which contractions become stronger due to stimulation before complete relaxation occurs. A) Tetanus B) Wave summation C) Muscle Tone D) Multiple motor unit summation E) Maximal stimulus

B) Wave summation -Temporal aka wave summation, occurs because the second contraction occurs before the muscle has completely relaxed.

A sacromere is the distance between two ___. A) A band B) Z discs C) I band D) Myosin

B) Z discs -A sarcomere is defined as the segment between two neighbouring Z-lines (or Z-discs, or Z bodies). In electron micrographs of cross-striated muscle, the Z-line (from the German "Zwischenscheibe", the band in between the I bands) appears as a series of dark lines.

What structure in skeletal muscle cells functions in calcium storage? A) intermediate filament network B) sacroplasmic reticulum C) mitochondria D) myofibrillar network

B) sacroplasmic reticulum SR is an elaborate smooth endoplasmic reticulum. Its interconnecting tubules surrounds each myofibril the way a sleeve surrounds your arm.

Myoglobin ___. A) produces the end plate potential B) stores oxygen in muscle cells C) breaks down glycogen D) is a protein involved in the direct phosphorylation of ADP

B) stores oxygen in muscle cells

Destroys ACh. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

C) Acetylcholinesterase -An enzyme located in the synaptic cleft. -Acetylcholine aka ACh.

Marathons A) Anaerobic Pathway B) Direct Phosphorylation C) Aerobic Pathway

C) Aerobic Pathway

The ___ contains only the actin filaments. A) A band B) Z discs C) I band D) Myosin

C) I band -Surrounding the Z-line is the region of the I-band (for isotropic).

Determined by alternating motor units of a muscle organ even when the muscle is at rest. A) Tetanus B) Wave summation C) Muscle Tone D) Multiple motor unit summation E) Maximal stimulus

C) Muscle Tone -All skeletal muscle is maintained in a constant, slightly contracted state - spinal reflexes activate groups of motor units alternately

Fatigued muscle cells that recover rapidly are the products of ___. A) slow exercise of short duration B) intense exercise of long duration C) intense exercise of short duration D) slow exercise of long duration

C) intense exercise of short duration

Only ____ muscle cells commonly branch.

Cardiac

The time in which cross bridges are active is called the period of ____.

Contraction

A neurotransmitter released at motor end plates by the axon terminals. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

D) Acetylcholine -The chemical compound acetylcholine (often abbreviated ACh) is a neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans. Acetylcholine is one of many neurotransmitters in the autonomic nervous system (ANS) and the only neurotransmitter used in the motor division of the somatic nervous system. (Sensory neurons use glutamate and various peptides at their synapses.) Acetylcholine is also the principal neurotransmitter in all autonomic ganglia.

Excitation-contraction coupling requires which of the following substances? A) ATP and glucose B) ATP only C) Ca2+ only D) Ca2+ and ATP

D) Ca2+ and ATP

How a smooth increase in muscle force is produced. A) Tetanus B) Wave summation C) Muscle Tone D) Multiple motor unit summation E) Maximal stimulus

D) Multiple motor unit summation -The force of contraction is controlled more precisely by recruitment also called multiple motor unit summation.

The thicker filaments are the ___ filaments. A) A band B) Z discs C) I band D) Myosin

D) Myosin -Myosin filaments are bipolar and extend throughout the A-band. They are crosslinked at the centre by the M-band.

What is the role of tropomyosin in skeletal muscles? A) Tropomyosin is the receptor for the motor neuron neurotransmitter. B) Tropomyosin is the chemical that activates the neuron neurotransmitter. C) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on teh myosin molecules. D) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

D) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

The strongest muscle contractions are normally achieved by ___. A) increasing stimulus above the treppe stimulus B) recruiting small and medium muscle fibers C) increasing stimulus above the threshold D) increasing the stimulation up to the maximal stimulus

D) increasing the stimulation up to the maximal stimulus

Which of the following is a factor that affects the velocity and duration of muscle contraction? A) muscle length B) number of muscle fibers stimulated C) size of the muscle fibers stimulated D) load on the fiber

D) load on the fiber

Which of the following would be recruited later in muscle stimulation when contractile strength increases? A) many small motor units with the ability to stimulate other motor units B) motor units with the longest muscle fibers C) large motor units with small, highly excitable neurons D) motor units with larger, less excitable neurons

D) motor units with larger, less excitable neurons

Used to convert ADP to ATP by trnsfer of high-energy phosphate group. A reserve high-energy compound. A) Calcium Ions B) Sodium Ions C Acetylcholinesterase D) Acetylcholine E) Creatine phosphate

E) Creatine phosphate -Phosphocreatine, also known as creatine phosphate or PCr (Pcr). -Excercise vigorously, the demand for ATP soars and the ATP stored in working muscles is consumed within a few twitches. The creatine phosphate (CP), a unique high-energy molecule stored in muscles, is tapped to regenerate ATP while the metabolic pathways are adjusting to the suddenly higher demands of ATP. The result of coupling CP with ADP is almost instant transfer of energy and a phosphate group from CP to ADP to form ATP.

The stimulas above which no stronger contraction can be elicited, because all motor units are firing in the muscle. A) Tetanus B) Wave summation C) Muscle Tone D) Multiple motor unit summation E) Maximal stimulus

E) Maximal stimulus -The strongest stimulus that produces increased contractile force.

Muscle contraction will always promote movement of body parts regardless of how they are attached. True / False

False

During isotonic contraction, the heavier the load, the faster the velocity of contraction. True / False

False -Isotonic - muscle length changes and moves the load. -iso = same -ton = tension

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate. True / False

False -Motor unit not motor end plate.

During isometric contraction, the energy used appears as movement. True / False

False -Muscles act to hold joints in stationary positions while movement occurs at other joints.

Once a motor neuron has fired, all the muscle fibers in a muscle contract. True / False

False -When a motor neuron fires (transmits an action potential), all the muscle fibers it innervates conract. -innervate = stimulate to action.

The end of the muscle that typically moves when a muscle contracts is called the _____.

Insertion

_____ (color) fibers are slow (oxidative) fibers.

Red

Only ______ muscle cells are always multinucleated.

Skeletal

Cells of unitary (single-unit) smooth muscle are found in the longitudnal and circular muscle layers of the intestine. True / False

True -Single-unit smooth muscle, commonly called visceral muscle because it is in the walls of all hollow organs except the heart.

Although there are "no" sacromeres, smooth muscle still possesses thick and thin filaments. True / False

True -sacromere = muscle segment -The smallest contractile unit of a muscle fiber.

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops. True / False

True

Contractures are a result of a total "lack" of ATP. True / False

True

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units. True / False

True

Smooth muscles relax when intercellular Ca2+ (calcium ion) levels drop but may not cease contractions. True / False

True

The force of muscle contraction is controlled by multiple motor unit summation or recruitment. True / False

True

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment. True / False

True

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length. True / False

True

Eccentric contractions are more forceful than concentric contractions. True / False

True -Eccentric contractions - muscle generates force as it lengthens in your calf muscles as you walk up a hill. -Concentric contractions - muscle shortens and does work, such as picking up a book or kicking a ball.

A contraction in which the muscle does not shorten but its tension increases is called isometric. True / False

True -Isometric - tension may build to the muscle's peak, tension producing capacity, but the muscle neither shortens or lengthens. -iso = same -metric = measure

A resting potential is caused by a differnece in the concentration of certain ions inside and outside the cell. True / False

True -Like the plasma membranes of all celss, a resting sarcolemma is polarized. There is pltential difference across the membrane and the inside is negative relative to the outer membrane face.

One of the important functions of skeletal muscle contraction is a production of heat. True / False

True -Muscles perform at least four functions: movement, maintains posture, stabilize joints and generates heat.

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily. True / False

True -Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse.[1] Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of the synapse. Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow graded electrical potentials.

Peristalsis is characteristic of smooth muscle. True / False

True -Peristalsis - the wavelike muscular contraction of the intestine or other tubular structure that propel the contents onward by alternate contraction and relaxation.

The giant protein titin maintains the orgainzation of the ___ assisting in muscle stretching. a) A band b) I band c) Z disc d) M line

a) A band

Which of the following is true about smooth muscle contraction? a) Certain smooth muscle cells can actually divide to increase their numbers. b) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. c) Smooth muscle cannot stretch as much as skeletal muscle. d) Smooth muslce has well-developed T tubules a the site of invagination.

a) Certain smooth muscle cells can actually divide to increase their numbers.

The tissue that binds muscles into functional groups. Connective tissue covering the exterior of a muscle organ. a) Epimysium b) Endomysium c) Muscle Fiber d) Fascicle e) Perimysium

a) Epimysium -"outside the muscle" -An "overcoat" of dense irregular connective tissue that surrounds the whole muscle.

Which of the following statements is most accurate? a) Muscle tension remains relatively constant during isotonic contraction. b) T tubules may be sliding during isotonic contraction. c) The I band lengthens during isotonic contraction. d) Myofilaments slide during isometric contractions.

a) Muscle tension remains relatively constant during isotonic contraction.

A sarcomere is defined as the segment between two neighboring Z-lines (or Z-discs, or Z bodies). In electron micrographs of cross-striated muscle, the ___. a) Z disc b) H zone c) I band d) A band e) M line

a) Z disc -(from the German "Zwischenscheibe", the band in between the I bands) appears as a series of dark lines.

What is the functional unit of a skeletal muscle called? a) a sarcromere b) a myofilament c) a myofibril d) the sarcoplasmic reticulum

a) a sarcomere

The sliding filament model of contraction involves ___. a) actin and myosin sliding past each other and partially overlapping b) the shortening of thick filaments so that thin filaments slide past c) actin and myosin shortening but not sliding past each other d) the Z discs sliding over the myofilaments

a) actin and myosin sliding past each other and partially overlapping

In an isotonic contraction, the muscle ___. a) changes in length and moves the "load" b) does not change in length but increases tension c) never converts pyruvate to lactate d) rapidly resynthesizes creatine phosphate and ATP

a) changes in length and moves the "load"

What part of the sarcolemma contains acetylcholine receptors? a) motor end plate b) end of the muscle fiber c) part adjacent to another muscle cell d) any part of the sarcolemma

a) motor end plate

Which of the following is the correct sequence of events for muscle contractions? a) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, AtP-driven power stroke, sliding of myofilaments b) neurotransmitter release, muscle cell action potential, motor reuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke c) muslce cell action potential, neurotransmitter release, atp-driven power stroke, calcium ion release from SR, sliding of myofilaments d) neurotransmitter rlease, motor neuron cation potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

a) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, AtP-driven power stroke, sliding of myofilaments

Muscle tissue has all of the following properties except ___. a) secretion b) contractility c) extensibility d) excitability

a) secretion

Which of the following are composed of myosin? a) thick filaments b) thin filaments c) all myofilaments d) Z discs

a) thick filaments -Thick filaments containing myosin (red). -Thin filaments containing actin (blue).

Within the A-band is a polar region called the ___. (a) Z disc b) H zone c) I band d) A band e) M line

b) H zone -From the German "Heller", bright). Named for their properties under a polarization microscope. -Thick filaments only.

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers? a) a sprint by an Olympic runner b) a long, relaxing swim c) playing baseball or basketball d) mountain climbing

b) a long, relaxing swim

The term aponeurosis refers to ___. a) the bands of myofibrils b) a sheetlike indirect attachment to a skeletal element c) the rough endoplasmic reticulum d) the tropomyosin-troponin complex

b) a sheetlike indirect attachment to a skeletal element

During muscle contraction, myosin across bridges attach to which active sites? a) myosin filaments b) actin filaments c) Z discs d) thick filaments

b) actin filaments

Which of the following surrounds the individual muscle cells? a) perimysium b) endomysium c) epimysium d) fascicle

b) endomysium -Endomysium = within the muscle. -Is a whispy sheath of connective tissue that surrounds each individual muscle fiber.

What is the functional role fo theT tubules? a) stabilize the G and F actin b) enhance cellular communication during muscle contraction c) hold cross bridges in place in a resting muscle d) synthesize ATP to provide energy for muscle contraction

b) enhance cellular communication during muscle contraction

An enaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ___. a) the citric acid cycle b) glycolysis c) hydrolysis d) the electron transport chain

b) glycolysis

What controls the force of muscle contraction? a) wave summation b) multimotor unit summation c) treppe d) concentric contractions

b) multimotor unit summation -Recruitment also called multimotor unit summation. -Recruitment is achieved by delivering shocks of increasing voltage to the muscle, calling more and more muscle fibers into play.

Smooth muscles that act like skeletal muscles but are controlled by autonomic nerves and hormones are ___. a) single-unit muscles b) multiunit muscles c) red muscles d) white muscles

b) multiunit muscles

Of the following muscle types, which has only one nucleus, no sacromeres, and rare gap junctions? a) visceral smooth muscle b) multiunit smooth muscle c) cardiac muscle d) skeletal muscle

b) multiunit smooth muscle

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overalpped, ___. a) cross bridge attachment would be optimum because of all the free binding sites on actin b) no muscle tension could be generated c) maximum for ce production would result because the muscle has a maximum range of travel d) ATP consumption would increase because the sarcomere is "trying" to contract

b) no muscle tension could be generated

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? a) relaxation period b) refractory period c) latent period d) fatigue period

b) refractory period -During repolarization, a muscle fiber is in the refractory period, because the cell cannot be stimulated again until repolarization is complete. -Repolarization - the sarcolemma is restored to its initial polarized state. -sarcolemma = plasma membrane

The muscle cell membrane is called the ___. a) endomysium b) sarcolemma c) perimysium d) epimysium

b) sarcolemma

What produces the striations of a skeletal muslce cell? a) a difference in the thickness of the sarcolemma b) the arrangement of myofilaments c) the sarcoplasmic reticulum d) the T tubules

b) the arrangement of myofilaments

Smooth muscle is charaterized by all of the following except ___. a) it appears to lack troponin b) there are more thick filaments than thin filaments c) there are no sarcomeres d) there are noncontractile intermediate filaments taht attach to dense bodies within the cell

b) there are more thick filaments than thin filaments

Which of the following statements is false or incorrect? a) Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells. b) Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute. c) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP. d) Cardiac muscle fibers can use lactic acid to make ATP

c) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.

Surrounding the Z-line is the region of the ___. a) Z disc b) H zone c) I band d) A band e) M line

c) I band -I-band (for isotropic) -Isotropy is uniformity in all directions; it is derived fromt he Greek iso (equal) and tropos (direction). -Thin filaments only.

Individual muscle fiber. Skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated and called___. a) Epimysium b) Endomysium c) Muscle Fiber d) Fascicle e) Perimysium

c) Muscle Fiber

Which of the following statements is true? a) Cardiac muscle cells have many nuclei. b) Smooth muscle cells have T tubules. c) Striated muscle cells are long and cylindrical with many nuclei. d) Cardiac muscle cells are found in the heart and large blood vessels.

c) Striated muscle cells are long and cylindrical with many nuclei.

Muslce tone is ___. a) the ability of a muscle to efficiently cause skeletal movements b) the feeling of well-being following exercise c) a state of sustained partial contraction d) the condition of athletes after intensive training

c) a state of susteained partial contraction

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? a) calcium ions returning to the terminal cisternae b) the tropoyosin blocking the myosin once full contraction is achieved c) acetylcholinesterase destroying the ACh d) the actin potential stips going down the overloaded T tubules

c) acetylcholinesterase destroying the ACh

What is the role of calcium ions in muslce contraction? a) form hydoxyapatite cyrstals b) reestablish glycogen stores c) bind to regulatory sites on troponin to remove contraction inhibition d) increase levels of myoglobin

c) bind to regulatory sites on troponin to remove contraction inhibition

Which of the following is "not" a way muscle contractions can be graded? a) changing the frequency of stimulation b) changing the strength of the stimulas c) changing the type of muscle fibers involved in the contraction d) changing the type of neurotransmitter released by the motor neuron

c) changing the type of muscle fibers involved in the contraction

Which of the following is "not" a result of resistance exercise? a) increase in the efficiency of the respiratory system b) increase in the efficiency of the circulatory system c) increase in the number of muscle cells d) increase in the number of myofibrils within the muscle cells

c) increase in the number of muscle cells

Which of the choices below does "not" describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions? a) converts lactic acid back into glycogen stores in the liver b) resynthesizes creatine phosphate and ATP in muscle fibers c) increases the level of lactic acid in the muscle d) replaces the oxygen removed from myoglobin

c) increases the level of lactic acid in the muscle

The oxygen-binding protein found in muscle cells is ___. a) hemoglobin b) ATP c) myoglobin d) immunoglonin

c) myoglobin

Rigor mortis occurs because ___. a) the cells are dead b) sodium oions leak out of the muscle c) no ATP is available to release attached actin and myosin molecules d) proteins are beginning to break down, thus preventing a flow of calcium ions

c) no ATP is available to release attached actin and myosin molecules

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ___. a) actin and myosin interact by the sliding filament mechanism b) the trigger for contraction is a rise in intracellular calcium c) the site of calcium regulation differs d) ATP energizes the sliding process

c) the site of calcium regulation differs

Which of the following describes the cells of single-unit visceral muscle? a) they contract all at once. b) They are chemically coupled to one another by gap junctions. c) they exhibit spontaneous action potentials. d) They consist of muscle fibers that are structurally independent of each other.

c) they exhibit spontaneous action potentials.

The warm-up period required of athletes in order to bring their muscles to peak performance is called ___. a) twitch b) wave summation c) treppe d) incomplete tetanus

c) treppe

Following the I-band is the ___. a) Z disc b) H zone c) I band d) A band e) M line

d) A band -(for anisotropic). Named for their properties under a polarizing microscope. -Anisotropic is the property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. -Thick and thin filaments overlap.

Which of the following is not a role of ionic calcium in muscle contraction? a) triggers neurotransmitter secretion b) promotes contraction inhibitor c) removes contraction inhibitor d) activates epinephrine released from adrenal gland

d) activates epinephrine released from adrenal gland

The main effect of the warm-up period of athletes, as the muscle contractions increase in strenth, is to ___. a) increase the myoglobin content b) convert glycogen to glucose c) tone the muscles and stabilize the joints for the workout d) enhance the availability of calcium and the efficiency of enzyme systems

d) enhance the availability of calcium and the efficiency of enzyme systems

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for engery. As a result, the pyruvic acid is converted to ___. a) a strong base b) stearic acid c) hydorchloric acid d) lactic acid

d) lactic acid -When muscles contract vigorously and contractile activity reaches about 70% of the maximum possible (anerobic conditions), most of the pyruvic acid produced during glycolysis is converted into lactic acid, and the overall process is referred to as anaerobic glycolysis.

The contractile units of skeletal muscles are ___. a) microtubules b) mitochondria c) T tubules d) myofibrils

d) myofibrils

The major function of the sarcoplasmic reticulum in muscle contraction is to ___. a) make and store phosphocreatine b) synthesize actin and myosin myofilaments c) provide a source of myosin for the contraction process d) regulate intracellular calcium concentration

d) regulate intracellular calcium concentration

What is the most distinguishing characteristic of muscle tissue? a) the design of the fibers b) the sarcoplasmic reticulum c) the diversity of activity of muscle tissue d) the ability to transform chemical energy into mechanical energy

d) the ability to transform chemical energy into mechanical energy

Inside the H-zone is a thin ___. a) Z disc b) H zone c) I band d) A band e) M line

e) M line -(from the German "Mittel", middle of the sarcomere).

Around the fasicles. Connective tissue surrounding muscle fiber bundles. a) Epimysium b) Endomysium c) Muscle Fiber d) Fascicle e) Perimysium

e) Perimysium -A sheath of connective tissue that groups individual muscle fibers (anywhere between 10 to 100 or more) into bundles of fascicles.