Skeletal Muscles
E
Acetylcholinesterase is found within the A) nucleus. B) sarcolemma. C) myofibril. D) sarcomere. E) synaptic cleft.
E
Muscle cells A) actively lengthen. B) generate compression. C) possess a mechanism that regulates the tension amount by changing the number of contracting sarcomeres. D) vary tension production based on the amount of sodium ions bound to actin. E) can only contract.
B
"Anaerobic endurance" A) is used during long, slow athletic activities. B) is exemplified by contractions of fast muscle fibers. C) is determined by the availability of carbohydrates, lipids, or amino acids for breakdown. D) is the length of time a muscle can continue to contract while supported by mitochondrial activities. E) does not promote muscle hypertrophy.
E
A layer of collagen fibers that surrounds an entire muscle is called A) endomysium. B) perimysium. C) sarcolemma. D) sarcomere. E) epimysium.
B
A muscle that inserts on the radial tuberosity or the ulnar tuberosity is most likely involved in A) elbow extension. B) elbow flexion. C) elbow abduction. D) pronation. E) protraction.
C
A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more ________ in his or her leg muscles. A) fast fibers B) intermediate fibers C) slow fibers D) dark fibers E) red fibers
C
A resting muscle generates most of its ATP by A) conversion of creatine phosphate. B) anaerobic respiration. C) aerobic respiration. D) glycolysis. E) heat loss.
B
A sheath of connective tissue surrounding a bundle of striated muscle fibers is called A) endomysium. B) perimysium. C) sarcolemma. D) epimysium. E) sarcoplasmic reticulum.
E
A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a(n) A) incomplete tetanus. B) latent period. C) complete tetanus. D) summation. E) twitch.
D
Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tubule is tightly bound to A) the nucleus. B) the sarcolemma. C) the endomysium. D) the sarcoplasmic reticulum. E) thick filaments.
D
Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose? A) neurons B) cardiac muscle cells C) skeletal muscle fibers D) liver cells E) erythrocytes
D
Regarding muscle fiber elongation, A) many active mechanisms exist for muscle fiber elongation. B) muscle contraction is passive; whereas, elongation is active. C) opposing muscle movements are not a factor. D) gravity may help lengthen a muscle fiber after elongation. E) elastic forces are generated where a muscle fiber elongates.
B
Skeletal muscle fibers differ from "typical cells" in that these muscle fibers A) lack a plasma membrane. B) have many nuclei. C) are very small. D) lack mitochondria. E) contain endoplasmic reticulum.
E
Smooth muscle A) does not use calcium. B) is not resistant to fatigue. C) contracts faster than skeletal muscle. D) does not undergo tetanus. E) uses primarily aerobic metabolism.
E
Smooth muscle cells A) have to be innervated by motor neurons. B) are larger than cardiac muscle cells. C) are multinucleate. D) contain intercalated discs. E) are spindle-shaped.
E
Structure B A) protects the myofibrils. B) attaches to actin molecules. C) produces ATP. D) conducts nerve impulses through the muscle cell. E) stores calcium.
C
Structure C is the A) myofibril. B) Z line. C) sarcoplasmic reticulum. D) T tubule. E) myofilament.
B
Structure E is the A) ligament. B) sarcolemma. C) sarcoplasmic reticulum. D) epimysium. E) endomysium.
B
Structure G is composed of A) actin. B) myosin. C) troponin. D) tropomyosin. E) sarcoplasmic reticulum.
B
Structure H is the A) thick myofilament. B) thin myofilament. C) Z line. D) H band. E) M lines.
B
Structure I is composed of A) actin and perimysium. B) actin and myosin. C) troponin and tropomyosin. D) only myosin heads. E) acetylcholine and cholinesterase.
E
Structure J represents a A) myosin head. B) sarcomere. C) T tubule. D) myofilament. E) myofibril.
A
The muscle that inserts on the coronoid process of the mandible is the A) temporalis. B) masseter. C) orbicularis oris. D) zygomaticus. E) platysma.
C
The muscle that originates from the superior surface of the pubis around the symphysis is the A) internal oblique. B) external oblique. C) rectus abdominis. D) transversus abdominis. E) diaphragm.
B
The muscle that would be used to blow air into a trumpet or a clarinet is the A) zygomaticus minor. B) buccinator. C) orbicularis oris. D) masseter. E) temporalis.
D
The insertion of the anterior part of the frontalis muscle is the A) temporal bone. B) epicranial aponeurosis. C) occipital bone. D) skin of the eyebrow and the bridge of the nose. E) coronoid process of the mandible.
C
The less-movable end of a skeletal muscle is the A) insertion. B) belly. C) origin. D) proximal end. E) distal end.
D
The region of a sarcomere containing myosin, going from one end of the myosin molecules to the other end of the myosin molecules, is the A) Z line. B) M line. C) H band. D) A band. E) I band.
D
The skeletal muscles store calcium ions in the terminal cisternae of the A) sarcolemma. B) sarcomere. C) sarcosome. D) sarcoplasmic reticulum. E) sarcoplasm.
B
The specialized sarcolemma that contains acetylcholine receptors is the A) synaptic knob. B) motor end plate. C) motor unit. D) synaptic cleft. E) I band.
D
The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of A) cAMP. B) DNA. C) RNA. D) ATP. E) tRNA.
D
The striated appearance of skeletal muscle results from A) the transverse tubule pattern. B) the sarcoplasmic reticulum. C) cisternae placement. D) actin and myosin arrangement. E) the perimysium arrangement.
A
The structures labeled F are the A) mitochondria. B) sarcomeres. C) nuclei. D) centrioles. E) troponin molecules.
D
The term used to describe muscular growth in response to usage is A) multiple sclerosis. B) muscular dystrophy. C) atrophy. D) hypertrophy. E) myopathy.
B
The terminal cisternae are structural features of the A) myofilaments. B) sarcoplasmic reticula. C) myofibrils. D) I bands. E) sarcolemma.
D
The triad, seen as structure D, is composed of A) the T tubules and the myofibrils. B) actin and myosin. C) troponin and tropomyosin. D) the cisterna of the sarcoplasmic reticulum along with the T tubules. E) the cisterna of the sarcoplasmic reticulum and the myofilaments.
D
Which of the following inserts into a tendinous sheet, rather than a bone? A) extensor carpi ulnaris B) flexor carpi radialis C) extensor digitorum D) palmaris longus E) flexor digitorum
B
Which of the following inserts into the intertubercular groove of the humerus and acts to extend, adduct, and rotate the shoulder? A) supraspinatus B) latissimus dorsi C) serratus anterior D) triceps brachii E) trapezius
D
Which of the following terms is a descriptive word for a muscle's action? A) obliques B) costalis C) biceps D) adductor E) pectinate
E
Which statement regarding "heat loss" is true? A) Muscle activity does not generate heat. B) Shivering in a cold environment results in higher levels of heat loss. C) When skeletal muscles are contracting at peak levels, body temperature drops. D) Heat loss is reduced when blood flow to the skin increases. E) Muscle contractions play an important role in the maintenance of normal body temperature.
C
Which statement regarding isometric contractions is true? A) Tension rises during a contraction. B) The skeletal muscle's length changes. C) The tension produced never exceeds the load. D) Tension remains at a constant level until relaxation occurs. E) Examples are walking and running.
E
Which statement regarding skeletal muscle is true? A) Skeletal muscles are directly, but not indirectly, attached to bones. B) Skeletal muscles do not contain connective tissue. C) Skeletal muscles do not maintain body temperature. D) Skeletal muscles do not contain nervous tissue. E) Skeletal muscles contain blood vessels.
B
Which statement regarding the relaxation phase of a muscle twitch is true? A) The phase begins at stimulation and typically lasts about two milliseconds. B) Muscle tension falls to resting levels. C) The action potential sweeps across the sarcomere during this period. D) Tension rises to a peak. E) Cross-bridges are interacting with active sites on actin filaments throughout this period.
D
Why do individual muscle twitches have to be added together, as in summation or tetanus? A) Only added twitches produce any muscle contraction: A fiber undergoing a muscle twitch does not contract at all. B) There has to be a critical mass of muscle twitches for calcium to be released into the muscle cell. C) Not enough acetylcholine will be produced for contraction without multiple twitches. D) Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle. E) Not enough ATP is generated by one muscle twitch.
A
A muscle ________ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils. A) fiber B) intercalated disc C) T-tubule D) myofibril E) motor end plate
C
In infants, which muscle allows for the mouth to form a tight fit around the nipple during suckling at the breast? A) masseter B) buccinator C) orbicularis oris D) risorius E) levator labii
D
In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases A) acetylcholine. B) sodium ions. C) potassium ions. D) calcium ions. E) acetylcholinesterase.
E
You are lying on the floor with your feet flat and your knees up practicing your abdominal crunches. You raise your upper body to the ceiling, up and down. What muscles are you using to the greatest extent? A) diaphragm B) rectus abdominus C) pectoralis major D) internal intercostals E) transverse abdominis
A
Myofibrils are made primarily of A) actin and myosin. B) epimysium. C) ATP and ADP. D) troponin. E) tropomyosin.
E
After death, rigor mortis lasts until A) ATP is produced. B) T-tubules recapture calcium ions. C) sodium ions are released by the sarcoplasmic reticulum. D) sarcomeres lengthen. E) myofilaments are broken down.
B
As a skeletal muscle contraction is initiated, acetylcholine binding alters the motor end plate membrane's permeability to A) acetylcholinesterase. B) sodium ions. C) calcium ions. D) chloride ions. E) potassium ions.
E
Botulism A) is the result of an attack on acetylcholine receptors by the immune system. B) is usually tied to a genetic predisposition. C) is a viral illness. D) results from the loss of acetylcholine receptors at the motor end plate. E) results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals.
A
Calcium ions are released from the sarcoplasmic reticulum during the ________ phase of contraction. A) latent B) contraction C) twitch D) relaxation E) recovery
C
Choose the correct statement regarding motor units. A) Muscle fibers of each motor unit are not mingled with those of other motor units. B) During a sustained contraction, all motor units are activated simultaneously. C) A motor neuron may control only two or three muscle fibers of the eye muscle(s). D) When muscles contract for sustained periods, maximal tension is maintained. E) Most motor neurons control fewer than five muscle fibers.
B
Creatine phosphate serves to A) cause the decomposition of ATP. B) supply energy to synthesize ATP. C) decompose ADP. D) synthesize ADP. E) synthesize glucose.
C
During activities requiring aerobic endurance, A) glycogen and glycolysis are the primary sources of reserve energy. B) amino acids are not broken down. C) most of the muscle's energy is produced in mitochondria. D) fatigue occurs in a few minutes. E) muscle hypertrophy often occurs.
C
During moderate activity, which of the following is true regarding muscle metabolism? A) The ATP produced is used to build energy reserves of ATP and glycogen. B) Most ATP is produced through glycolysis, with lactate and hydrogen ions as byproducts. C) Glucose and fatty acids are catabolized. D) Mitochondrial activity provides about one-third of the ATP consumed. E) Mitochondria are not involved.
A
During which phase is the stimulus frequency so high that the relaxation phase is eliminated? A) complete tetanus B) a twitch C) incomplete tetanus D) recovery E) recruitment
C
Each myofibril consists of approximately ________ sarcomeres. A) 10 B) 500 C) 10,000 D) 100,000 E) 2-3 million
D
Exhaustion of energy reserves or decline in pH due to production and dissociation of lactic acid causes A) muscle contraction. B) the conduction of neural information to the muscle fiber. C) muscle relaxation. D) muscle fatigue. E) the striated appearance of skeletal muscle.
D
Fast fibers A) have loosely packed myofibrils. B) have a high concentration of myoglobin. C) have many mitochondria. D) have high glycogen reserves. E) are about half the diameter of slow fibers.
A
Glycolysis A) is an anaerobic process. B) is the breakdown of pyruvate to glucose. C) acts as the only source of ATP in muscle tissue. D) is only active during rest. E) occurs in the nucleus.
D
Label A is pointing to A) myofibrils. B) Z lines. C) sarcoplasmic reticulum. D) T tubules. E) myofilaments.
B
Looking at the muscle name sternocleidomastoid, you would identify that this muscle is located in the area of the A) leg. B) neck. C) back. D) abdomen. E) arm.
B
Muscle fascicles are separated by A) endomysium. B) perimysium. C) epimysium. D) sarcolemma. E) periosteum.
B
Neurotransmitters that cause skeletal muscle contraction are normally stored in A) myofibrils. B) motor neuron axon terminals. C) motor units. D) motor end plates. E) actin.
C
Nonstriated, involuntary muscle is A) cardiac. B) red skeletal. C) smooth. D) white skeletal. E) intermediate skeletal.
D
Place these steps of muscle contraction in the correct order. 1. Action potential is generated along the sarcolemma 2. Nerve impulse arrives at synapse 3. Calcium is released into muscle cell cytoplasm 4. Acetylcholine is produced 5. Actin and myosin molecules continuously cross-link, with actin molecules being pulled inward A) 2, 3, 4, 1, 5 B) 4, 2, 1, 5, 3 C) 1, 2, 4, 3, 5 D) 2, 4, 1, 3, 5 E) 1, 2, 4, 5, 3
A
The ________ contains vesicles filled with acetylcholine. A) axon terminal B) motor end plate C) neuromuscular junction D) synaptic cleft E) transverse tubule
B
The active sites on actin molecules are usually covered up by other molecules. What is the critical material required to uncover the active sites on the actin molecules that will then bind to myosin heads? A) ATP B) calcium C) oxygen D) vitamin A E) titin
A
The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the A) oxygen debt. B) refractory oxygen amount. C) anaerobic oxygen threshold. D) aerobic oxygen threshold. E) aerobic oxygen conversion.
B
The area between Z lines is the A) sarcolemma. B) sarcomere. C) sarcoplasmic reticulum. D) myofibril. E) myofilament.
C
The area of the sarcomere that is the light region between two successive A-bands is the A) Z line. B) M line. C) I band. D) myofibril. E) H band.
C
The deltoid acts to A) flex the wrist. B) medially rotate the shoulder. C) abduct the arm. D) adduct the arm. E) laterally rotate the shoulder.
A
The difference in the action when comparing the biceps brachii to the flexor carpi radialis, is A) one muscle flexes the hand at the wrist and the other flexes the entire forearm. B) one muscle flexes the arm and the other extends the arm. C) one moves the ulna and the other moves the radius. D) one of these muscles is voluntary while the other is involuntary. E) the shapes of the two muscles differ.
A
The enzyme acetylcholinesterase causes acetylcholine to A) break down. B) synthesize. C) bond to actin. D) be secreted. E) form cross-bridges.
A
The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because A) the heart muscle has to be able to consistently contract and pump blood in a controlled fashion. B) heart muscle is not resistant to fatigue. C) heart muscle contracts faster than skeletal muscle. D) heart muscle cannot use glycogen. E) the heart uses aerobic metabolism.
C
Tropomyosin strands are held in position by which of the following? A) actin molecules B) myosin molecules C) troponin molecules D) ATP molecules E) calcium ions
E
Upon the nerve impulse arriving at the axon terminal, A) active sites on actin are exposed. B) active sites on myosin are exposed. C) actin heads will bind to myosin. D) muscle relaxation occurs. E) acetylcholine is released.
B
What is the function of the transverse tubule? A) the storage of calcium ions B) to transmit electrical impulses to the cell's interior C) to store sodium ions D) to allow cross-bridge attachment E) to produce myofibrils
D
Which muscle extends the elbow during the action of push-ups? A) deltoid B) trapezius C) brachialis D) triceps brachii E) biceps brachii
E
Which muscle inserts on the clavicle and the acromion and spine of the scapula? A) serratus anterior B) levator scapulae C) sternocleidomastoid D) pectoralis minor E) trapezius
C
Which muscle is not attached in some way to the scapula? A) teres minor B) deltoid C) sternocleidomastoid D) teres major E) infraspinatus
D
Which muscle is not part of the rotator cuff set of muscles? A) supraspinatus B) subscapularis C) teres minor D) biceps brachii E) teres major
B
Which muscle would not move the scapula? A) rhomboid B) erector spinae C) serratus anterior D) pectoralis minor E) trapezius
C
Which muscle(s) would produce a twisting of the upper body? A) rectus abdominus B) spinalis group C) external and internal oblique muscles D) diaphragm E) quadratus lumborum
C
Which of the following describes the action of the trapezius? A) adducts the spine B) adducts and flexes the humerus C) elevates, adducts, depresses, or rotates the scapula D) provides medial rotation of the head E) provides lateral rotation of the humerus
A
Which of the following is a muscle that originates from the zygomatic arch and functions in elevating the mandible? A) masseter B) frontalis C) digastric D) temporalis E) medial pterygoid
B
Which of the following is an accurate characteristic of slow fibers? A) Slow muscle tissue has a much less extensive network of capillaries than does typical fast muscle tissue. B) Resting slow muscle fibers contain oxygen reserves, bound to myoglobin. C) Slow muscle tissue has a lower oxygen supply than does fast muscle tissue. D) Slow muscle fibers contain fewer mitochondria than do fast muscle fibers. E) Slow muscle fibers contain myoglobin, a globular protein, which binds sodium.
A
Which of the following is characteristic of cardiac muscle? A) Cardiac muscle cells are striated. B) Cardiac muscle cells achieve tetany with every contraction. C) Cardiac muscle fibers are multinucleated. D) Cardiac muscle fibers are faster than skeletal muscles. E) Neurons that innervate cardiac muscle tissue are under voluntary control.
D
Which of the following is one of the steps that ends a contraction? A) Sarcoplasmic reticulum absorbs sodium ions. B) Acetylcholine binds to receptors on the sarcolemma. C) Calcium ions bind to troponin. D) Acetylcholine is broken down by acetylcholinesterase. E) An action potential spreads across the entire surface of the muscle fiber.
E
Which of the following is the origin of the pectoralis minor? A) vertebral border near the spine B) coracoid process of the scapula C) superior portion of the sternum D) occipital bone of the skull E) anterior surfaces of ribs 3-5
A
Which of the following is true about red muscles? A) Red muscles are slower than white muscles. B) Red muscles have fewer mitochondria than white muscles. C) Red muscles have fibers of greater diameter than those of white muscles. D) Red muscles contain less myoglobin than white muscles. E) Red muscles fatigue quickly.
A
Which of the following muscles functions to maintain an erect spinal column and head? A) erector spinae B) biceps brachii C) triceps brachii D) rectus femoris E) biceps femoris
C
Which of the following muscles is named for its shape? A) pectoralis major B) biceps brachii C) deltoid D) erector spinae E) tibialis anterior
C
Which of the following occurs as a result of motor units in a particular muscle being always active, even though their contractions do not produce enough movement to cause contraction? A) treppe B) tetany C) muscle tone D) fatigue E) a twitch
B
Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria? A) Pyruvate levels drop in the cytoplasm. B) Lactic acid is produced. C) Pyruvate is converted to sucrose. D) Lactic acid dissociates into a water molecule and hydrogen. E) Oxygen is produced.
D
Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur? A) resting period B) latency C) tension plateau D) incomplete tetanus E) complete tetanus
C
Which of the following originates from the cartilages of ribs 2-6, the sternal body, and the clavicle? A) teres minor B) supraspinatus C) pectoralis major D) teres major E) subscapularis
E
Which of the following statements describes how muscles help maintain homeostasis? A) The contractions of skeletal muscles pull on tendons and move elements of the skeleton. B) Skeletal muscles are responsible for guarding the openings of the digestive and urinary tracts. C) Skeletal muscles are responsible for the pumping action of the heart. D) Skeletal muscles support the weight of some internal organs. E) Skeletal muscle contractions help maintain body temperature.
