CH.6 The Muscular System

The following events are associated with muscle contraction. Which one of the following best describes the order in which these events occur, following the initiation of a contraction by a nerve impulse? 1. T tubules transmit electrical impulses throughout the muscle cell. 2. Myosin contacts actin and pulls it toward the center of the sarcomere. 3. Acetylcholine binds to receptors on themuscle. 4. Troponin-tropomyosin complex shifts to expose myosin binding sites. 5. Calcium is released from the sarcoplasmic reticulum. A) 3, 1, 5, 4, 2 B) 1, 3, 5, 2, 4 C) 3, 5, 1, 2, 4 D) 4, 2, 1, 3, 5 E) 3, 5, 1, 4, 2

A) 3, 1, 5, 4, 2

All of the following occur during the latent period of muscle contraction EXCEPT which one? A) Myofibrils shorten. B) Calcium is released from the sarcoplasmic reticulum. C) Muscle cell membrane initiates an electrical impulse, which travels into the muscle cell. D) Myosin heads bind to actin filaments. E) Troponin-tropomyosin complex shifts, exposing myosin heads.

A) Myofibrils shorten.

Which one of the following statements correctly describes the origin and insertion of a muscle? A) The insertion is pulled toward the origin during contraction. B) The origin is pulled toward the insertion during contraction. C) The origin of a muscle is generally distal (farther from the body's mid-line) relative to the insertion. D) The origin and insertion refers to the growth pattern of a muscle during development. E) There is always a ligament at the origin of a muscle and a tendon at the insertion.

A) The insertion is pulled toward the origin during contraction.

Cardiac muscle differs from skeletal muscle in that A) all cardiac muscle is under involuntary control. B) cardiac muscle is capable of relaxation. C) cardiac muscle contracts in response to an electrical or chemical signal. D) cardiac muscle is excitable and can shorten. E) cardiac muscle gets longer rather than shorter when excited.

A) all cardiac muscle is under involuntary control.

During a marathon, runners use up ATP and glucose early in the race. Which energy source is generally used next for producing more ATP? A) glycogen B) starch C) cellulose D) steroids E) phospholipids

A) glycogen

Contraction of a skeletal muscle cell is initiated by the A) release of acetylcholine by a neuron terminating at the neuromuscular junction. B) release of calcium ions by the neuron into the neuromuscular junction. C) electrical current traveling from the neuron directly into the muscle cell. D) hormones delivered by the blood supply to the nearby tissue. E) release of sodium ions by the neuron into the neuromuscular junction.

A) release of acetylcholine by a neuron terminating at the neuromuscular junction.

When an electrical impulse traveling along a motor neuron arrives at a neuromuscular junction A) there is an increase in the secretion of acetylcholine at the neuromuscular junction. B) calcium is transported back to the sarcoplasmic reticulum. C) sliding of actin and myosin filaments is inhibited. D) myosin-actin cross-bridges are destroyed. E) a new electrical impulse is generated that returns the message to the original nerve.

A) there is an increase in the secretion of acetylcholine at the neuromuscular junction.

At the end of the contractile period, energy from the breakdown of ATP is used to A) transport calcium back into the sarcoplasmic reticulum. B) repair any muscle damaged during contraction. C) digest energy sources to generate new ATP for the next round of contractions. D) produce lactic acid. E) unlink the troponin-tropomyosin complexes.

A) transport calcium back into the sarcoplasmic reticulum.

Which one of the following statements is TRUE regarding the structure of a muscle? A) The outer surface of a muscle is enclosed by many layers of epidermis. B) All muscle cells in a muscle have the same origin and insertion. C) Fascicles of a muscle are surrounded by a thin sheath of hyaline cartilage. D) Connective tissues associated with the muscle converge to form a ligament at each end of the muscle. E) Each fascicle consists of two muscle cells.

B) All muscle cells in a muscle have the same origin and insertion.

Which one of the following statements correctly describes activities of muscles? A) All muscles produce movement. B) All muscles shorten when they contract. C) All muscles are under conscious control. D) All muscles are attached to bones. E) All muscles are synergistic.

B) All muscles shorten when they contract.

Muscle cells produce lactic acid when they have an inadequate supply of A) protein. B) O2. C) calcium. D) actin and myosin. E) glycogen.

B) O2.

Following electrical stimulation of a muscle cell, calcium functions toA) stimulate the enzymes that produce ATP.B) bind to theprotein troponin.C) leak out of the muscle cell to re-establish the membrane potential.D) break down acetylcholine.E) maintain the relaxed state of the muscle.

B) bind to theprotein troponin.

Intercalated discs A) are characteristic of smooth muscle cells. B) contain gap junctions that allow the signal to spread quickly through cardiac muscle cells. C) support fast-twitch fibers of skeletal muscle. D) stimulate pacemaker cells in cardiac muscle. E) stimulate the contraction of skeletal muscle.

B) contain gap junctions that allow the signal to spread quickly through cardiac muscle cells.

In which one of the following would one expect to find motor units made up of only a few muscle cells? A) arm muscles B) eye muscles C) chest muscles D) thigh muscles E) lower-leg muscles

B) eye muscles

Which one 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) helps an individual maintain posture

B) moves an object or part of the skeleton

Which sequence lists the structures from largest, most inclusive, tosmallest? A) muscle-thick filament-fascicle-muscle fiber-myofibril B) muscle-fascicle-muscle fiber-myofibril-thick filament C) fascicle-muscle-myofibril-muscle fiber-thick filament D) muscle fiber-myofibril-muscle-fascicle-thick filament E) thick filament-fascicle-myofibril-muscle-muscle fiber

B) muscle-fascicle-muscle fiber-myofibril-thick filament

Which one of the following is an example of an isometric contraction? A) person lifting books from the floor B) tightening of abdominal muscles while sitting C) kicking a soccer ball D) swinging a golf club E) doing abdominal "crunches"(sit-ups)

B) tightening of abdominal muscles while sitting

In comparing smooth and cardiac muscle, which one of the following best describes the differences between the two muscle types? A) Smooth muscle is voluntary, whereas cardiac is involuntary. B) Both lack muscle filaments, but cardiac muscle has sarcomeres. C) Cardiac muscle requires periods of relaxation, whereas smooth muscle is always in a state of partial contraction. D) Cardiac muscle filaments are arranged in bundles, whereas smooth muscles lack filament bundles. E) Cardiac muscle contracts slowly compared to smooth muscle

C) Cardiac muscle requires periods of relaxation, whereas smooth muscle is always in a state of partial contraction.

Which one of the following is the most efficient long-term source of ATP for muscle cells? A) creatine phosphate B) ready-madeATP in the cell C) aerobic respiration of glucose D) fermentation of glucose E) aerobic respiration of proteins

C) aerobic respiration of glucose

The primary energy source used by muscle cells to generate ATP is A) steroids. B) glycogen. C) glucose. D) starch. E) fatty acids.

C) glucose.

As part of your fitness training, you do biceps curls lifting two 10-lb weights. The muscle contractions enabling these movements are A) isometric contractions. B) tetanic contractions. C) isotonic contractions. D) tendon-mediated contractions. E) ligament-mediated contractions.

C) isotonic contractions.

Which one of the following activities would fast-twitch fibers be most useful for? A) distance running B) swimming C) lifting weights D) biking E) cross-country skiing

C) lifting weights

Which one of the following is characteristic of cardiac and smooth muscle, but not skeletal muscle? A) voluntary contraction B) striated appearance C) presence of gap junctions D) presence of actin and myosin in muscle cells E) contraction is initiated by motor neurons

C) presence of gap junctions

T, or transverse, tubes in skeletal muscle function to A) transport calcium ions throughout muscle cells. B) allow actin and myosin filaments to slide over each other. C) promote the rapid penetration of the electrical impulse deep into the cell. D) help decrease the amount of ATP produced. E)convert glucose to lactic acid, which helps muscles relax.

C) promote the rapid penetration of the electrical impulse deep into the cell.

An individual with the condition of myasthenia gravis is faced with an autoimmune disorder in which the body defenses attack acetylcholine receptors on muscle cells. What would be the expected effect on calcium levels near contractile proteins, following the arrival of an electrical impulse at those neuromuscular junctions?A) a rapid decrease in concentration due to uptake by sarcoplasmic reticulum B) a rapid increase in concentration due to release by sarcoplasmic reticulum C) small or no increases in concentration due to weak responses by acetylcholine receptors D) a large decrease in concentration that occurs slowly E) a large increase in concentration that occurs slowly

C) small or no increases in concentration due to weak responses by acetylcholine receptors

Skeletal muscle groups that work together to create the same movement are referred to as A) involuntary. B) antagonistic. C) synergistic. D) sarcomeres. E) myofibrils.

C) synergistic.

Which one of the following is found within a sarcomere? A) the muscle cell nuclei B) muscle fibers C) the actin and myosin filaments D) fascicles E) fascia

C) the actin and myosin filaments

A myogram is a recording of A) the electrical activity of muscle cells. B) the electrical activity of nerves at neuromuscular junctions. C) the activity of muscle cells. D) blood pressure changes resulting from muscle contraction.E) the movement of myosin filaments.

C) the activity of muscle cells.

All of the following are necessary for contraction to occur EXCEPT which one? A) Calcium levels must increase in close proximity to the contractile proteins. B) ATP must be present. C) Troponin-tropomyosin complex must shift out of the way. D) Cross-bridges must form between actin and myosin. E) The troponin and tropomysin must slide relative to each other, shortening the sarcomere.

E) The troponin and tropomysin must slide relative to each other, shortening the sarcomere.

Plantar fasciitis is an inflammation of the fascia within the sole of the foot, resulting in foot and heel pain. What is a fascia? A) a bundle of muscle cells that are enclosed in a connective tissue sheath B) a bundle of protein filaments (thick and thin) located within muscle cells C) the fibrous connective tissue sheath that surrounds the fascicles of the muscle D) a connective tissue structure that attaches one muscle to another muscle E) the area where the actin and myosin filaments overlap within a muscle cell

C) the fibrous connective tissue sheath that surrounds the fascicles of the muscle

n comparing all three major muscle types, which one of the following statements best describes the differences between them? A) Cardiac muscle can be stimulated only by nerves, whereas smooth and skeletal muscle contract spontaneously. B) Smooth and skeletal muscles appear striated, due to the arrangement of muscle filaments, whereas cardiac muscles lack these filaments. C) Only cardiac muscle is under voluntary control. D) Smooth and cardiac muscle do not fatigue, whereas skeletal does fatigue. E) Gap junctions are present in skeletal muscles, but not in other types of muscle.

D) Smooth and cardiac muscle do not fatigue, whereas skeletal does fatigue

n the lower leg, the gastrocnemius muscle bends the foot away from the knee, as in pointing one's toes. The tibialis anterior muscle flexes the foot toward the knee. These two muscles are A) synergistic. B) homeostatic. C) mutualistic. D) antagonistic. E) cooperative.

D) antagonistic.

Once a muscle cell has depleted its small supply of ready-made ATP, what will it use next for energy? A) fats B) phospholipids C) proteins D) creatine phosphate E) glycogen

D) creatine phosphate

Following intense exercise, the human body attempts to overcome oxygen debt by A) sweating. B) elevating heart rate. C) producing ATP. D) taking deep breaths. E) inhibiting contractions of smooth muscle.

D) taking deep breaths.

In order for a muscle contraction to occur, cross-bridges must form between which one of the following structures within a muscle cell? A) the plasma membrane and the sarcoplasmic reticulum B) troponin and tropomyosin C) calcium and tropomyosin D) acetylcholine and muscle cell receptors E) actin and myosin

E) actin and myosin