Chapter 6 - The Muscular System

Once muscle cells use up their supply of ATP, they must produce more ATP in order to continue to contract. Which of the following is not used as an energy source for ATP production? A. actin and myosin B. creatine phosophate C. glycogen D. fatty acids E. glucose

A. actin and myosin

Which of the following is an example of an isotonic contraction? A. person lifting books from the floor B. tightening of abdominal muscles while sitting C. maintaining an upright position D. attempting to move heavy furniture that won't budge E. all of these

A. person lifting books from the floor

Cardiac, smooth, and skeletal muscle cells have many characteristics in common. Which of the following is not one of these characteristic? A. under voluntary control B. capable of relaxation C. contract in response to an electrical or chemical signal D. excitable E. capable of shortening

A. under voluntary control

Which of the following is characteristic of muscle relaxation? A. There is an increase in the secretion of a neurotransmitter at the neuromuscular junction. B. Calcium is transported back to the sarcoplasmic reticulum. C. The presence of ATP is not required. D. Myosin-actin cross-bridges are formed E. Sarcomeres shorten

B. Calcium is transported back to the sarcoplasmic reticulum

Which of the following is not true regarding muscle tone? A. Muscle tone is an intermediate force that results from the alternating contraction and relaxation of the various motor units in a muscle. B. Muscle tone results from the contraction of all the motor units in a muscle followed by the relaxation of all the motor units in a muscle. C. The maintenance of muscle tone requires stimulation from the nervous system. D. Muscle tone decreases when less motor units of a muscles are activated. E. "Recruitment" results in an increase in muscle tone.

B. Muscle tone results from the contraction of all the motor units in a muscle followed by the relaxation of all the motor units in a muscles.

Rigor mortis results from _______ after death. A. the presence of acetylocholine in the neuromuscular junctions of muscles cells B. lack of ATP in muscles C. the degeneration of muscles D. lack of calcium in muscles the absence of carbon dioxide

B. lack of ATP in muscles

Which of the following is characteristic of an isotonic muscle contraction but not an isometric muscle contraction? A. generates a force B. moves an object or part of the skeleton C. helps an individual maintain an upright position D. requires energy E. used to maintain posture

B. moves an object or part of the skeleton

Which of the following is not an example of aerobic exercise? A. jogging B. weight lifting C. biking D. swimming E. walking

B. weight lifting

Which of the following is not true regarding muscle contraction? A. The troponin-tropomysocsin complex will prevent myosin from contacting actin unless calcium is present. B. A nerve impulse is required to initiate contraction. C. A muscle shortens as myosin is pulled towards the center of sarcomeres by actin. D. Electrical impulses transmitted by T tubules cause the release of calcium from the sarcoplasmic reticulum. E. Muscle contraction requires energy.

C. A muscle shortens as myosin is pulled towards the center of sarcomeres by actin

Which of the following does not require ATP as an energy source? A. transport of calcium into the sarcoplasmic reticulum B. detachment of myosin from actin C. binding of acetylcholine to muscle cell receptors D. formation of myosin-actin cross-bridges E. bending of myosin head

C. binding of acetylcholine to muscle cell receptors

Which of the following is not true regarding the contraction of muscle? A. results in movement B. generates heat C. causes a muscle to lengthen D. helps a person maintain posture E. is followed by relaxation of the muscle

C. causes a muscle to lengthen

The need to breathe rapidly after exercise helps to increase the amount of oxygen delivered to muscle tissue. Why is this additional oxygen needed after exercise has been completed? A. is used to initiate anaerobic respiration of glucose B. it increases the individual's oxygen debt C. is used to replenish energy supplies in muscles D. helps to decrease the amount of ATPs produced E. is used to convert glucose to lactic acid, which helps muscles relax

C. is used to replenish energy supplies in muscles

Which of the following activities would depend on the contraction of fast-twitch fibers? A. jogging B. swimming C. lifting weights D. biking E. maintaining body posture

C. lifting weights

Which of the following is characteristic of cardiac and smooth muscle, but not skeletal muscle? A. voluntary contraction B. striated appearance C. presence of gap juntions D. presence of actin and myosin in muscle cells E. located in the wall of the heart

C. presence of gap junctions

Which of the following muscle does not have a striated appearance? A. cardiac B. skeletal C. smooth D. both smooth and cardiac E. both skeletal and cardiac

C. smooth

Which of the following proteins involved in muscle contraction also plays an enzymatic role in the breakdown of ATP? A. troponin B. actin C. tropomyosin D. myosin E. troponin and tropomyosin

D. myosin

Which of the following is true regarding the anaerobic metabolism of glucose in a muscle? A. requires the presence of oxygen B. results in the production of more ATP than the aerobic metabolism of glucose C. causes the breakdown of glycogen into glucose D. results in the production of lactic acid, which makes muscles sore E. provides a source of energy for the first 30 seconds of muscle activity

D. results in the production of lactic acid, which makes muscles sore

Which of the following is true regarding anabolic steroids? A. Anabolic steroids were first developed by pharmaceutical companies in the late 1800s for the treatment of diseases associated with muscle wasting. B. Anabolic steroids are developed from estrogen, the female sex hormone. C. Because the use of anabolic steroids is illegal without a prescription, the purchase of these compounds has decreased over the past twenty years. D. Anabolic steroids have been found to cause few side effects and do not pose a serious health risk. E. Anabolic steroids increase muscle mass and are thought to help improve athletic performance.

E. Anabolic steroids increase muscle mass and are thought to help improve athletic performance.

In order for a muscle contraction to occur, cross-bridges must form between structures within a muscle cell. These cross-bridges form between: A. the plasma membrane and the sarcoplasmic reticulum B. troponin and tropomyson C. calcium and tropomyosin D. acetylcholine and muscle cell receptors E. actin and myosin

E. actin and myosin

Which of the following is characteristic of anabolic steroid use? A. increased risk of heart attack and stroke B. gynecomastia in males C. aggressive behavior D. loss of scalp hair, but increase in body hair in females E. all of the above

E. all of the above

Calcium ions required for muscle contraction are stored in the _______ of a muscle fiber. A. T tubules B. plasma membrane C. mitochondria D. myosin E. sarcoplasmic reticulum

E. sarcoplasmic reticulum

T/F: A sarcomere is made up of thick filaments of protein called actin and thin filaments of protein called myosin. The myosin filaments attach directly to the Z line.

False

T/F: During a muscle contraction, the origin moves towards the insertion since the insertion is the end of the muscle that attaches to a bone across a joint.

False

T/F: When a motor neuron of a motor unit stimulated contraction of that unit, it causes approximately half of the muscle cells in that motor unit to contract at any one point in time. That way, the next time the motor unit is stimulated, other muscle cells of the unit are ready to contract.

False

T/F: According to the sliding filament mechanism, during a muscle contraction, myosin pulls actin filaments towards the center of a sarcomere, causing the entire sarcomere to shorten.

True

T/F: Isotonic contractions usually result in the movement of the skeleton or objects.

True

T/F: Most forms of exercise involve both isotonic and isometric muscle contractions.

True

T/F: Most of the muscles of the human body are composed of both fast-twitch and slow-twitch fibers, though the percentage of these fibers in a given muscle varies according to muscle function.

True

T/F: Muscle cells are located in every organ in the body and are essential in any activity that requires movement.

True

T/F: Muscles of the hand contain a high percentage of fast twitch fibers which allows for actions that are strong and quick.

True

T/F: Training of present-day athletes not only involves strenuous workouts, but also the use of video cameras, computer programs, and remote sensors.

True

Neurotransmitter

a chemical released by a neuron that may stimulate or inhibit other neurons or effector cells

Twitch

a complete cycle of contraction and relaxation in a muscle cell

Actin

a contractile protein of muscle; forms the thin filaments in the myofibrils

Fatigue

a decline in muscle performance during exercise

Muscular Dystrophy

a group of inherited muscle-destroying diseases

Motor Unit

a somatic motor neuron and all the muscle cells that it stimulates

In stimulated muscle cells, which causes myosin to be pulled further over actin? a. ATP hydrolysis b. calcium pumped to sarcoplasmic reticulum c. acetyl choline is released by a motor axon d. fascicles tweist and muscle fibers shorten

a. ATP hydrolysis

The sliding filament mechanism describes the process during which: a. actin and myosin slide relative to each other b. sarcomeres slide relative to each other c. troponin and tropomyosin slide relative to each other d. muscle fibers slide past each other

a. actin and myosin slide relative to each other

Thin filaments of _____ overlap thick filaments of ____ to compose sarcomeres. a. actin, myosin b. myosin, actin

a. actin, myosin

All of the following are functions of the muscular system except: a. maintenance of body calcium stores b. resisting movement c. maintenance of body temperature d. movement

a. maintenance of body calcium stores

In you run 5K several times a week, you will increase the ______ of ______ muscle fibers. a. size, slow-twitch b. number, slow-twitch c. size, fast-twitch d. number, fast-twitch

a. size, slow-twitch

Summation

accumulation of effects, especially those of muscular or neural activity

What is the first and most direct energy source for muscle contraction? a. glucose b. ATP c. creatine phosphate d. glycogen

b. ATP

When _____ is released from a motor axon to the neuromuscular junction, calcium is released from the _____, stimulating muscle contraction. a. calcium, sarcolemma b. acetyl cholin, sarcoplasmic reticulum c. acetyle choline, myofibrils d. calcium, sarcomeres

b. acetyl cholin, sarcoplasmic reticulum

As you clasp your hands in front of you and push them toward each other, this is an example of: a. an isontonic contraction b. an isometric contraction c. a tetanic contraction d. aerobic training

b. an isometric contraction

Muscles which oppose each other and produce opposite movements are described as: a. synergistic b. antagonistic c. cooperative d. oppostitional

b. antagonistic

Which represents bundles of muscle cells? a. fascia b. fascicles c. myofibrils d. sarcolemma

b. fascicles

In any muscle, even when relaxed, there are always some fibers contracted. This provides: a. exercise b. muscle tone c. tetanus d. summation

b. muscle tone

Which of the following would have motor units with the smallest number of muscle cells? a. thigh muscle b. muscles in fingers c. abdominal muscles d. muscles of the back

b. muscles in fingers

Which of the following is the site of calcium ion storage within muscles? a. T tubules b. sarcoplasmic reticulum c. actin filaments d. myosin filaments

b. sarcoplasmic reticulum

Biceps Brachii

bends forearm at elbow

Gastrocnemius

bends lower leg at knee and foot away from ankle

Which of the following choices arranges the structures (1) muscle fiber, (2) fascicle, (3) myofibril, and (4) muscle from the largest (most inclusive) to smallest? a. 1-2-3-4 b. 2-3-1-4 c. 4-2-1-3 d. 4-2-3-1

c. 4-2-1-3

All of the following may happen in response to exercise training except: a. increase in the number of myofibrils b. increase in the storage of glycogen and creatine phosphate c. increase in the number of muscle fibers d. increase in the number of mitochondria

c. increase in the number of muscle fibers

Botulism toxin inhibits the release of acetylcholine at the neuromuscular junction. What effect does this have on the muscle activity? a. muscles will contract continuously b. muscles will contract sporadically, without conscious control c. muscles will not contract because they will not receive nerve stimulation d. there will be no effect on muscle activity

c. muscles will not contract because they will not receive nerve stimulation

Which provides a reserve source of oxygen for an active muscle fiber? a. pyruvate b. lactic acid c. myoglobin d. creatine

c. myoglobin

Which is the function unit of skeletal muscle? a. myofibrils b. muscle fibers c. sarcomeres d. sarcoplasmic reticulum

c. sarcomeres

Which of the following happens during muscle contraction? a. actin filaments shorten b. myosin filaments shorten c. sarcomeres shorten d. both a and b

c. sarcomeres shorten

Which type of muscle can you control voluntarily? a. smooth b. cardiac c. skeletal

c. skeletal

Which type(s) of muscle cells can contract the fastest? a. smooth muscle cells b. cardiac muscle cells c. skeletal muscle cells d. all muscle cell can exhibit the same speed of contraction

c. skeletal muscle cells

External Oblique

causes lateral rotation of the trunk and abdominal compression

Myofibrils

cylindrical structures arranged in parallel inside a muscle cell

What is the role of AT in muscle function? a. ATP provieds energy which enables myosin to form cross-bridges with actin b. ATP enables myosin to detach from actin c. ATP provides energy to transport calcium back into storage d. all of the above

d. all of the above

Which attaches your muscles to your bones? a. tendons b. origin - attaches to stationary bone c. insertion - attaches to the mobile bone d. all of the above

d. all of the above

Which type(s) of muscle cells can contract spontaneously? a. smooth muscle cells b. cardiac muscle cells c. skeletal muscle cells d. both a and b

d. both a and b

Which of the following is/are characteristic of slow-twitch fibers? a. large amounts of glycogen storage b. myoglobin content enables oxygen storage c. numerous mitochondria d. both b and c

d. both b and c

Calcium controls muscle contraction by binding a regulatory protein on actin, this _____________ allowing myosin to increase its overlap with actin. a. causes myosin to hydolyze AT{ then bind actin b. keeps calcium from being pumped back into the sarcoplasmic reticulum c. changes the configuration of sarcomeres in myofibrils d. exposes myosin binding sites

d. exposes myosin binding sites

Tetanus

disease caused by a bacterial infection; bacterial toxin affects primarily the muscles of the jaw and neck; also known as "lockjaw"

Myasthenia Gravis

disorder caused by an individual's immune system; acetylocholine receptors on muscle cells are destroyed; primarily affects muscles of eyes, neck, and face

Triceps Brachii

extends forearm at elbow

Tibialis Anterior

flexes foot toward knee

Quadricepts

flexes thigh at the hip; extends leg at knee

Recruitment

increasing the tone (or force) of a muscle by activating more motor units

Fasciitis

inflammation of the connective tissue layers surround a muscle; common in the sole of the foot

Trapezius

lifts and braces shoulders; draws head back

Skeletal Muscles

muscle composed of cylindrical multinucleate cells with obvious striations; attach to the body's skeleton

Motor Neuron

neuron in the peripheral nervous system that conducts nerve impulses from the central nervous system to body tissues and organs

Myosin

one of the principal contractile proteins found in muscle; composed of thick filaments with cross-bridges

Deltoid

raises arm

Sarcoplasmic Reticulum

specialized endopasmic reticulum of muscle cells that surrounds the myofibrils and stores the calcium needed for the initiation of muscle contraction

Oxygen Debt

the amount of oxygen required after exercise to oxidize the lactic acid formed by anaerobic metabolism during exercise

Insertion

the end of a muscle that attaches to another bone across a joint

Origin

the end of a muscles that is attached to the bone that does not move during muscular contraction

Muscular Dystrophy

the group of muscular diseases that are hereditary; results in muscle wasting; no cure

Sliding Filament Mechanism

the mechanism of muscle contraction; muscles contract when the thick and thin filaments slide past each other and sarcomeres shorten

All-Or-None Principle

the principle that muscle cells always contract completely each time they are stimulated by their motor neuron, and that they do not contract at all if they are not stimulated by their motor neuron

Sarcomere

the smallest contractile unit of a muscle myofibril; extends from one Z-line to the next

Muscle Cramps

uncontrolled contraction of muscle, usually after heavy exercise