Ch. 9 practice questions
3) How many muscles are there in the muscular system? A) 50 B) 206 C) thousands D) 700+ E) 116
D) 700+
22) The structure of each myosin molecule includes ________. A) a double myosin strand B) an attached elongated tail C) a free globular head D) All of the answers are correct. E) None of the answers are correct.
D) All of the answers are correct.
40) What type of muscular activity is present in a muscle at rest? A) There is no activity. B) There is some activity that causes the muscle to make continual tiny movements. C) Motor units activate partially in a unified wavelike motion. D) Motor units activate in a random pattern to cause slight constant tension, known as muscle tone. E) There are large amounts of short contraction.
D) Motor units activate in a random pattern to cause slight constant tension, known as muscle tone.
20) Which of the following is true of myosin molecules? A) They have a core of nebulin. B) They make up the thin filaments. C) They interact with the thick filaments. D) They form the globular heads called cross-bridges. E) All of the answers are correct.
D) They form the globular heads called cross-bridges.
33) The motor neuron releases its neurotransmitter, which then binds to receptors sites on a special region of the sarcolemma called ________. A) a T tubule B) the motor unit C) a fascicle D) a motor end plate E) the sarcoplasmic reticulum
D) a motor end plate
7) Skeletal muscle fiber contractions are caused by the interaction between the ________ and the ________ filaments of the sarcomeres. A) actin; nebulin B) titin; actin C) myosin; nebulin D) actin; myosin E) titin; myosin
D) actin; myosin
8) When acetylcholine binds to receptors on the motor end plate, ________ occurs immediately. A) vesicular enzymatic activity B) cross-bridge formation C) ATP-myosin binding D) an action potential E) myosin head pivoting
D) an action potential
46) While wearing a cast due to breaking a bone, muscles shrink due to the process of ________. A) recruitment B) cell division C) hypertrophy D) atrophy E) chronic inflammation, or swelling
D) atrophy
24) The sarcoplasmic reticulum stores ________. A) oxygen. B) glucose. C) ATP. D) calcium ions. E) glycogen.
D) calcium ions.
10) Most of the skeletal muscle fibers in the body are called ________ fibers, in reference to their duration of contraction following stimulation. A) red B) intermediate C) slow D) fast E) All of the answers are correct.
D) fast
67) Which of the following words means slender? A) longissimus B) brevis C) latissimus D) gracilis E) major
D) gracilis
32) Each skeletal muscle fiber is controlled by a single ________. A) synaptic cleft B) motor end plate C) triad of transverse tubule and terminal cisternae D) motor neuron whose cell body is located inside the central nervous system E) neurotransmitter
D) motor neuron whose cell body is located inside the central nervous system
41) When one motor neuron fires a single action potential the result affects one ________. A) upper motor neuron B) synaptic cleft C) lower motor neuron D) motor unit E) sensory unit
D) motor unit
57) If a muscle has a tendon that branches within the muscle tissue, it is (a) ________. A) sphincter muscle B) parallel muscle C) circular muscle D) multipennate muscle E) None of the answers are correct.
D) multipennate muscle
4) Between the endomysium and the muscle fibers lie a number of scattered cells that aid in the repair of damaged muscle tissues. These cells are the ________ cells. A) myoblast B) myofibril C) isotropic D) myosatellite E) myosin
D) myosatellite
45) When all of the motor units of a muscle contract at the maximal rate of stimulation, it leads to the production of ________. A) the longest contraction B) the fastest contraction C) multiple motor unit summation D) peak tension E) fast, long contractions
D) peak tension
43) When a single motor neuron controls a greater number of muscle fibers in a motor unit, ________. A) the greater the number of stimuli will be required to produce a contraction B) each contraction will last longer C) the muscle contraction will be slower D) the less precise the control will be E) None of the answers are correct.
D) the less precise the control will be
12) An intermediate fiber contracts fast, and it has more ________ and greater resistance to fatigue in comparison to a fast fiber. A) calcium ions B) myoglobin C) ribosomes D) oxygen-binding pigments E) mitochondria
E) mitochondria
12) Which of these orders of functional muscle structures progresses from the smallest to largest in diameter? A) muscle, fascicle, muscle fiber, myofibril B) fascicle, myofibril, muscle fiber, filament C) fascicle, muscle fiber, myofibril, muscle D) muscle, muscle fiber, myofibril, fascicle E) myofibril, muscle fiber, fascicle, muscle
E) myofibril, muscle fiber, fascicle, muscle
50) Slow twitch fibers appear red due to the intracellular storage of ________. A) nebulin B) titin C) hemoglobin D) glycogen E) myoglobin
E) myoglobin
7) A space that separates the expanded tip of the axon at the neuromuscular synapse from the motor end plate is the synaptic vesicle.
false - called synaptic cleft
4) The Z line is comprised of thick filaments attached to interconnecting proteins, delineating the ends of the sarcomere.
false - comprised of thin filaments...
9) A muscle that opposes the action of a prime mover is a synergist.
false - should be antagonist
1) The M line is located at the end of a sarcomere.
false - z-line
11) The fulcrum lies between the applied force and the resistance in a first-class lever.
true
2) At the zone of overlap, each thin filament sits in a triangle formed by three thick filaments, and each thick filament is surrounded by six thin filaments.
true
3) When viewed under polarized light, the dark staining bands are the A bands.
true
6) The expanded portion of the axonal branch that faces a region of the sarcolemma is called a synaptic terminal.
true
5) Light staining areas of a muscle fiber viewed under polarized light are called I bands.
true think about it - they're light because they only contain thin filaments; thin filaments WOULD look light!!
53) Two factors that are used to determine the classification of a skeletal muscle are (1) the arrangement of the muscle fibers. (2) the structural arrangement by which the muscles attach to the skeleton. (3) the overall size of the muscle. (4) the amount of connective tissue present within the muscle. (5) the number of tendons connected to the muscle. A) 1 and 2 B) 2 and 3 C) 3 and 4 D) 4 and 5 E) 1 and 3
A) 1 and 2 classification! not "name"
15) Why does a skeletal muscle fiber have more than one nucleus? A) During development, groups of embryonic cells fuse together to form a single muscle fiber. B) During development, the nucleus of each myoblast replicates several times. C) During development, the plasmalemmae of newly formed muscle fibers disintegrate, making many muscle cells into one. D) During muscular activity, parts of each muscle fiber break down, and the remaining parts, including their nuclei, fuse into new combination fibers. E) All of the answers are correct.
A) During development, groups of embryonic cells fuse together to form a single muscle fiber.
59) Regarding a typical muscle insertion, which of the following is TRUE? A) The insertion moves more than does the origin. B) The insertion is proximal to the origin. C) If a muscle extends between a broad aponeurosis and a narrow tendon, the aponeurosis is the insertion. D) If there are several tendons at one end of a muscle and just one at the other, there are multiple insertions. E) All of the answers are correct.
A) The insertion moves more than does the origin.
28) Which of the following is the FIRST step in the sliding mechanism of muscle contraction? A) The myosin heads of the thick filaments bind to active sites on the thin filaments. B) Myosin heads pivot toward the M line when cross-bridge binding occurs. C) Thin filaments are pulled toward the center of the sarcomere. D) The cross-bridges detach and return to their original positions. E) A carbohydrate molecule is broken down to produce energy.
A) The myosin heads of the thick filaments bind to active sites on the thin filaments.
13) Actinin molecules form an open meshwork at the ________. A) Z line B) M line C) H band D) I band E) A band
A) Z line
14) In a ________ muscle, the muscle fibers are based over a broad area, but all the fibers come together at a common attachment site. A) convergent B) spiral C) circular D) multipennate E) parallel
A) convergent
15) Typically, the insertion of a muscle is ________ to its origin. A) distal B) proximal C) medial D) lateral E) deep
A) distal
8) The layers of connective tissue surrounding a skeletal muscle from the inside to the outside in correct order are ________. A) endomysium, perimysium, and epimysium B) epimysium, endomysium, and perimysium C) epimysium, perimysium, and endomysium D) endomysium, epimysium, and perimysium E) perimysium, epimysium, and endomysium
A) endomysium, perimysium, and epimysium
5) What characteristic of muscle tissue allows it to respond to a stimulation by the nervous system? A) excitability B) elasticity C) extensibility D) contractility E) None of the answers are correct.
A) excitability
56) A bundle of muscle fibers within a skeletal muscle belly is called a ________. A) fascicle B) perimysium C) muscle sheath D) myofiber E) myofilament
A) fascicle
48) The largest muscle fiber type, which contains densely packed myofibrils, large glycogen reserves, and relatively few mitochondria, is called ________. A) fast fibers B) slow fibers C) intermediate fibers D) cardiac fibers E) smooth fibers
A) fast fibers
47) In muscles that have been repeatedly stimulated to produce near-maximal tension, the net effect is ________. A) hypertrophy B) recruitment C) atrophy D) reduced tone E) None of the answers are correct.
A) hypertrophy
5) Thick (myosin) and thin (actin) filaments together form ________. A) myofibrils B) the H band C) a triad D) Z discs E) the I band
A) myofibrils
11) Slow muscle fibers contain large amounts of the oxygen-binding protein ________. A) myoglobin B) calmodulin C) titin D) nebulin E) troponin
A) myoglobin
58) In the case of the triceps brachii, the shoulder is the ________; the olecranon is the ________. A) origin; insertion B) insertion; origin C) agonist; antagonist D) synergist, fixator E) None of the answers are correct.
A) origin; insertion
62) The adductor magnus muscle is so named, partially due to the ________. A) size of the muscle B) shape of the muscle C) parallel versus pennate arrangement of its fibers D) orientation of its muscle fibers E) location of the muscle
A) size of the muscle
5) Why does a person with muscles that have a higher percentage of slow fibers have greater endurance than a person with muscles that have a lower percentage of slow fibers?
Answer: A person with more slow fibers in a particular muscle will be better able to perform repeated contractions under aerobic conditions than one with a smaller percentage of this type of fibers. This is the case because the person with muscles that have a higher percentage of slow fibers will not fatigue as easily as the person whose muscles have a lower percentage. The slow fibers fatigue more slowly because the additional myoglobin they contain bind oxygen molecules, conferring substantial oxygen reserves to such muscles, which can be mobilized during a contraction. Another advantage of the higher percentage of slow fibers is a more extensive network of capillaries, which allow for greater blood flow and hence more red blood cells that can deliver more oxygen to the active muscle fibers.
1) How are oxygen and nutrients supplied to the tissues of a muscle?
Answer: Each muscle has an extensive vascular supply that carries oxygen and nutrients. These blood vessels often enter the epimysium alongside the associated nerves and follow the same branching pattern through the perimysium. Once within the endomysium, they form an extensive capillary network around each muscle fiber. each muscle vascularized enter epimysium beside nerves branch through perimysium endomysium - capillaries
2) Describe the composition and the arrangement of constituents within a myofibril.
Answer: Myofibrils consist of bundles of myofilaments, which are composed of several different types of proteins. Myosin and actin are the contractile proteins, which comprise the thick and thin filaments, respectively. Tropomyosin and troponin are regulatory proteins within the myofilaments, while titin and nebulin are accessory proteins. The thick (myosin) and thin (actin) filaments within a myofibril are arranged in repeating functional units called sarcomeres. All of the myofibrils are arranged parallel to the long axis of the cell, with the sarcomeres arranged side by side. As a result, the entire muscle fiber has a banded appearance corresponding to the bands of the individual sarcomeres. list all proteins remember titan and nebulin parallel
36) Which of the following events occurs in a muscle that is relaxing? A) The muscle fiber shortens. B) AChE is present in the synaptic cleft. C) Released calcium ions are present. D) Myosin heads bind to active sites on the thin filaments. E) Hydrolysis of ATP occurs.
B) AChE is present in the synaptic cleft.
38) Which of the following events occurs FIRST? A) Myosin cross-bridges attach to actin. B) Calcium ions are released from the sarcoplasmic reticulum. C) Calcium binds to troponin. D) The myosin head pivots toward the M line. E) The myosin head binds ATP and detaches from actin.
B) Calcium ions are released from the sarcoplasmic reticulum.
64) What does the name flexor carpi radialis most likely mean? A) It is a forearm muscle whose primary function is synergistic to that of the biceps brachii muscle. B) It is a lateral forearm muscle that flexes at the wrist. C) It is a convergent muscle found along the radial border of the forearm. D) The muscle originates at the wrist. E) All of the answers are correct.
B) It is a lateral forearm muscle that flexes at the wrist.
37) What is the significance of the change in permeability (transmembrane potential) of the sarcolemma in muscle contraction? A) It has no role, because this phenomenon does not occur. B) It triggers the release of calcium ions. C) This change is caused by a neurotransmitter. D) This change is caused by the displacement of actin and myosin molecules. E) None of the answers are correct.
B) It triggers the release of calcium ions.
65) How does a muscle named lateralis differ from one named latissimus? A) There is no difference; the two terms are synonymous. B) Lateralis refers to the side of the organism, whereas latissimus refers to the width of the structure. C) Latissimus means the structure is larger than one that is merely lateralis. D) Two muscles so named would always have completely different functions. E) A latissimus structure is always deep to a lateralis structure.
B) Lateralis refers to the side of the organism, whereas latissimus refers to the width of the structure.
7) Why are skeletal muscles called voluntary? A) These muscles maintain a constant rhythm of contraction. B) Their contractions can be consciously controlled. C) Only these muscles are stimulated to contract by the central nervous system. D) Contraction of specific muscles occurs to maintain body posture and body position. E) All of the answers are correct.
B) Their contractions can be consciously controlled.
34) The neurotransmitter involved in the process of contraction in skeletal muscles is ________. A) ATP B) acetylcholine C) troponin D) globulin E) serotonin
B) acetylcholine
61) The triceps brachii and biceps brachii are good examples of ________. A) muscles that flex the elbow B) an agonist-antagonist pair C) synergists D) agonists E) antagonists
B) an agonist-antagonist pair
1) Which of the following is the type of muscle that pushes blood through the arteries and veins of the circulatory system? A) skeletal muscle B) cardiac muscle C) smooth muscle D) appendicular muscle E) None of the answers are correct.
B) cardiac muscle
4) Which of the following features is NOT characteristic of muscle tissues? A) excitability B) cognitive ability C) contractility D) extensibility E) elasticity
B) cognitive ability
3) The connective tissue that surrounds each skeletal muscle fiber and binds each muscle fiber to its neighbor is the ________. A) endosteum B) endomysium C) epimysium D) periosteum E) perimysium
B) endomysium
44) When a resting muscle contracts only enough to produce tension without movement, this is an example of ________. A) activation B) muscle tone C) hypertrophy D) atrophy E) twitch
B) muscle tone
14) Skeletal muscle fibers arise from embryonic cells called ________. A) myotomes B) myoblasts C) myomeres D) myofilaments E) myofibrils
B) myoblasts
19) The structures within the muscle fiber that shorten to cause skeletal muscle fiber contraction are (the) ________. A) myoneural junctions B) myofibrils C) myosatellite cells D) neuromuscular synapses E) myoblasts
B) myofibrils
13) The biceps brachii is an example of a muscle with its fascicle oriented in a ________ fashion. A) convergent B) parallel C) bipennate D) circular E) multipennate
B) parallel
66) A word in a muscle name that indicates it is a pear-shaped muscle might be ________. A) splenius B) piriformis C) pectinate D) teres E) pyramidal
B) piriformis
6) The smallest functional units of the muscle fibers are the ________. A) fascicles B) sarcomeres C) myofilaments D) cisternae E) neuromuscular synapses
B) sarcomeres
63) What does the term longissimus in a muscle name primarily indicate about that muscle? A) the muscle location in the body B) the muscle length C) the manner in which the fibers of the muscle are oriented D) the insertion of the muscle fibers is oriented with respect to the long axis of the body E) the action of the muscle
B) the muscle length
29) The sliding mechanism of myofilaments works when ________. A) the thick filaments detach from the muscle tendon B) the myosin heads of the thick filaments bind to active sites on the actin molecules of the thin filaments C) the myosin heads pivot away from the M line toward the Z lines D) the troponin-tropomyosin complex interacts with the actin molecules E) calcium ions bind to active sites on the actin molecules of the thin filaments
B) the myosin heads of the thick filaments bind to active sites on the actin molecules of the thin filaments
16) Flexion of the forearm at the elbow involves the use of the principle of (a) ________ lever(s). A) first- and second-class B) third-class C) first-class D) first- and third-class E) second-class
B) third-class
25) Which of the following ions is the trigger for a muscle contraction? A) sodium B) chloride C) calcium D) ATP E) acetylcholine
C) calcium
49) Slow muscle fibers ________. A) are about two-thirds the diameter of fast fibers B) take twice as long to contract after stimulation as do fast fibers C) can continue to contract long after fast fibers have fatigued D) have less oxygen than do fast fibers E) None of the answers are correct.
C) can continue to contract long after fast fibers have fatigued
51) Slow fibers primarily use which of the following substrates for energy? A) glycogen B) lipids and carbohydrates through the anaerobic pathway C) carbohydrates, lipids, and amino acids through the aerobic pathway D) anaerobic metabolism E) protein
C) carbohydrates, lipids, and amino acids through the aerobic pathway
9) The epimysium, which separates the muscle from surrounding tissues and organs, is connected to the ________. A) superficial fascia B) subserous fascia C) deep fascia D) aponeuroses E) None of the answers are correct.
C) deep fascia
1) The ________ is a dense irregular connective tissue layer that surrounds the entire skeletal muscle. A) perimysium B) sarcolemma C) epimysium D) sarcoplasmic reticulum E) endomysium
C) epimysium
31) Regarding the effect of sarcomere length on tension production, a very highly stretched muscle (increased sarcomere length above normal 3.1 µm) will produce a contraction (% maximum tension) that is ________. A) optimal (100%) B) much greater than average (80-90%) C) fairly weak (20-40%) D) slightly stronger than resting position (~10%) E) None of the answers are correct.
C) fairly weak (20-40%)
17) Aging skeletal muscles develop increasing amounts of ________. A) glycogen reserves B) ATP C) fibrous connective tissue D) myoglobin E) myofibrils
C) fibrous connective tissue
26) The function of T tubules is to ________. A) bind muscle fibers together at the neuromuscular synapse B) separate the terminal from the motor end plate of the skeletal muscle fiber C) help distribute the electrical impulse, which triggers the release of calcium ions by the sarcoplasmic reticulum D) bind actin and myosin molecules together E) release acetylcholine into the synaptic cleft
C) help distribute the electrical impulse, which triggers the release of calcium ions by the sarcoplasmic reticulum
52) A very good sprinter is likely to have ________. A) more slow twitch fibers than average B) more intermediate fibers than average C) more fast twitch fibers than average D) average muscles; performance is based solely on training E) None of the answers are correct.
C) more fast twitch fibers than average
9) By varying the ________ at any one time, the nervous system provides precise control over the pull exerted by the muscle. A) reflexes triggered B) concentration of glycolytic enzymes C) number of motor units activated D) energy reserves utilized E) degree of muscle atrophy
C) number of motor units activated
16) The complex known as the triad consists of ________. A) actin, myosin, and myofilaments B) one A band, one H zone, and one I band C) one transverse tubule and two terminal cisternae D) myofilaments, myofibrils, and sarcomeres E) one sarcomere, one sarcoplasmic reticulum, and one sarcoplasm
C) one transverse tubule and two terminal cisternae
54) Muscle fibers can have various arrangements. The most powerful arrangement, in which more tension is generated during contraction, is called ________. A) circular B) parallel C) pennate D) convergent E) None of the answers are correct.
C) pennate
10) The connective tissue surrounding a bundle of muscle fibers is called ________. A) endomysium B) epimysium C) perimysium D) a tendon E) an aponeurosis
C) perimysium
2) Smooth muscles are primarily used to ________. A) generate heat B) pump blood through the circulation C) push fluid and solids along the digestive tract D) provide voluntary movements to the body E) pull on bones of the skeleton
C) push fluid and solids along the digestive tract
68) A lever in which the load is between the fulcrum and the applied force is a ________. A) first-class lever B) third-class lever C) second-class lever D) simple lever E) complex lever
C) second-class lever
18) The portion of a sarcomere that contains the thick filaments and the zone of overlap is the ________. A) I band B) M line C) A band D) H band E) Z line
C) A band
69) Which of the following is/are properties of a lever? A) It is a flexible structure. B) It is the effort produced by the muscle contraction. C) It moves on a fulcrum. D) It is the weight that opposes the applied force. E) All of the answers are correct.
C) It moves on a fulcrum.
10) A muscle that assists a prime mover is an agonist.
false
8) The sarcoplasmic reticulum conducts action potentials that spread across the sarcolemma into the cell.
false
35) The enzyme that is partly responsible for shutting down a muscle contraction is ________. A) actinin B) actinase C) acetylcholinesterase D) titin E) glycolytic enzyme
C) acetylcholinesterase
3) Why does a sarcomere itself appear to be banded, and what constituents comprise these bands?
Answer: Since all the proteins within a myofibril are organized in repeating units called sarcomeres, such an arrangement gives the sarcomere a banded appearance. The differences in the size and density of the thick (myosin) filaments and the thin (actin) filaments account for the banded appearance of the sarcomere. The thick filaments lie in the center of the sarcomere, linked by proteins of the central M line. Thin filaments at either end of the sarcomere, which are attached to interconnecting proteins that make up the Z lines, extend toward the M line. The Z lines delineate the ends of the sarcomere. In summary, the A band of a sarcomere includes the central M line, the H band (which has thick filaments only), and the zone of overlap (which has both thick and thin filaments). Between the A band and the Z line is the I band (which has thin filaments only). From the Z lines at either end of the sarcomere, thin filaments extend into the zone of overlap toward the M line. Under polarized light, the A (anisotropic) bands appear as dark bands and the I (isotropic) bands appear as light bands. list all the "bands"
6) What types of changes cause muscles to decrease in size and strength during the aging process?
Answer: Skeletal muscle fibers become smaller in diameter, primarily because there is a decrease in the number of myofibrils. The remaining myofibrils retain smaller amounts of ATP, glycogen reserves, and less myoglobin, which results in a decrease in muscle strength and endurance, as well as a tendency to fatigue rapidly.
4) How is muscle contraction regulated by tropomyosin and troponin?
Answer: The thin filament consists of a twisted strand, called F-actin, which is composed of 300-400 globular molecules of G-actin. A slender strand of the protein nebulin holds the F-actin strand together. Each molecule of G-actin contains an active site that can bind to the myosin heads of a thick filament. A thin filament also contains the regulatory proteins tropomyosin and troponin. Tropomyosin molecules form a long chain that covers the active sites, preventing actin-myosin interaction. Troponin holds the tropomyosin strand in place. Before a contraction can begin, the troponin molecules must change position, moving the tropomyosin molecules and hence exposing the active sites. If the active sites are covered, cross-bridge formation cannot occur and the muscle cannot contract. The interaction between calcium ions and troponin molecules is important in holding the tropomyosin strands in place, thereby exposing the active sites on the G-actin molecules. Therefore, the troponin-calcium ion interaction permits the tropomyosin molecule to change position, allowing for the contraction to begin.
17) The sarcoplasmic reticulum is (the) ________. A) plasmalemma of skeletal muscle fibers B) cytoplasm of skeletal muscle fibers C) a membrane complex similar to the smooth endoplasmic reticulum of skeletal muscle fibers D) extension of the skeletal muscle plasmalemma into the cell E) a membrane complex similar to the rough endoplasmic reticulum of skeletal muscle fibers
C) a membrane complex similar to the smooth endoplasmic reticulum of skeletal muscle fibers
30) When contraction occurs, ________. A) the A band remains constant B) the H band gets smaller C) the I band begins to disappear D) the Z lines move closer together E) All of the answers are correct.
E) All of the answers are correct.
39) Most of the time whole muscles do NOT contract at full strength because ________. A) only a few motor units are recruited at a given time B) we tend not to need the full capabilities of our muscles C) the muscle fibers of each motor unit are intermingled with those of other units, ensuring multiple motor unit summation D) the muscle fibers will use up their energy reserves and the muscle will be forced to relax E) All of the answers are correct.
E) All of the answers are correct.
6) Which of the following is a function of skeletal muscle? A) produce movement B) maintain posture C) support soft tissues D) maintain body temperature E) All of the answers are correct.
E) All of the answers are correct.
21) The area of a myofibril where there are no actin filaments is the ________. A) A band B) Z line C) I band D) M line E) H band
E) H band
23) Nebulin is which of the following types of molecules? A) functional hormone B) secretory protein C) regulatory protein D) enzyme E) accessory protein
E) accessory protein
60) A muscle whose contraction is mostly responsible for a movement is said to be the ________ for that movement. A) synergist B) agonist and fixator C) antagonist D) fixator E) agonist and prime mover
E) agonist and prime mover
27) Troponin assists in controlling the interaction between myosin heads and thin filaments by ________. A) forming a long chain that covers the active sites of thin filaments. B) storing calcium ions in the troponin-tropomyosin complex. C) binding to myosin heads, which allows tropomyosin to pivot, thereby exposing the active sites. D) assisting in the formation of the myofilaments. E) binding calcium ions to produce a change in the orientation of the troponin-tropomyosin complex.
E) binding calcium ions to produce a change in the orientation of the troponin-tropomyosin complex.
55) The muscles surrounding the entrances of the digestive and urinary tracts are classified as ________. A) convergent B) bipennate C) parallel D) multipennate E) circular
E) circular
11) The attachment of a muscle to a bone is called ________. A) a bursa B) an aponeurosis C) a ligament D) a capsule E) either a tendon or an aponeurosis
E) either a tendon or an aponeurosis
2) A skeletal muscle is divided into a series of internal compartments, each of which contains a bundle of muscle fibers called a ________. A) myofibril B) sarcomere C) triad D) cross-bridge E) fascicle
E) fascicle
42) The number of cells per motor unit in the leg muscles can reach up to ________. A) one hundred B) less than a dozen C) millions D) hundreds E) many thousands
E) many thousands