1) 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.
Answer: B
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
2) 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.
Answer: B
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
3) 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 midline) 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.
Answer: A
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
4) 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
Answer: A
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
5) 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
Answer: C
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
6) 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
Answer: C
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
7) In 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
Answer: D
Topic: Sec. 6.1
Skill: Application/Analysis
8) Which sequence lists the structures from largest, most inclusive, to smallest?
- 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
Answer: B
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
9) 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
Answer: C
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
10) 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
Answer: A
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
11) 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?
- T tubules transmit electrical impulses throughout the muscle cell.
- Myosin contacts actin and pulls it toward the center of the sarcomere.
- Acetylcholine binds to receptors on the muscle.
- Troponin-tropomyosin complex shifts to expose myosin binding sites.
- 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
Answer: A
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
12) 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
Answer: E
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
13) 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.
Answer: E
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
14) 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
Answer: A
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
15) 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
Answer: C
Topic: Sec. 6.2
Skill: Application/Analysis
16) The primary energy source used by muscle cells to generate ATP is
- A) steroids
- B) glycogen
- C) glucose
- D) starch
- E) fatty acids
Answer: C
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
17) 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
Answer: D
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
18) Which one of the following is the most efficient long-term source of ATP for muscle cells?
- A) creatine phosphate
- B) ready-made ATP in the cell
- C) aerobic respiration of glucose
- D) fermentation of glucose
- E) aerobic respiration of proteins
Answer: C
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
19) Muscle cells produce lactic acid when they have an inadequate supply of
- A) protein
- B) O2
- C) calcium
- D) actin and myosin
- E) glycogen
Answer: B
Topic: Sec. 6.2
Skill: Application/Analysis
20) 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
Answer: C
Topic: Sec. 6.3
Skill: Application/Analysis
21) 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
Answer: A
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
22) 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
Answer: A
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
23) 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
Answer: C
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
24) 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
Answer: B
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
25) 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)
Answer: B
Topic: Sec. 6.3
Skill: Application/Analysis
26) 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
Answer: D
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
27) Following electrical stimulation of a muscle cell, calcium functions to
- A) stimulate the enzymes that produce ATP
- B) bind to the protein 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
Answer: B
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
28) 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
Answer: C
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
29) 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
Answer: B
Topic: Sec. 6.3
Skill: Application/Analysis
30) 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.
Answer: A
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
31) 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
Answer: C
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
32) 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.
Answer: C
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
33) 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
Answer: C
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
34) In 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.
Answer: D
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
35) 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
Answer: B
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
6.2 True/False Questions
1) Muscle cells are located in every organ in the body except the stomach and are essential for any activity that requires movement.
Answer: FALSE
Topic: Sec. 6.0
Skill: Knowledge/Comprehension
2) Muscles constitute 60-70% of our body mass.
Answer: FALSE
Topic: Sec. 6.0
Skill: Knowledge/Comprehension
3) Muscle contraction accounts for over 75% of the heat generated by the body.
Answer: TRUE
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
4) In skeletal muscle, potassium ions are stored in the sarcoplasmic reticulum.
Answer: FALSE
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
5) The heads of myosin molecules contact the actin filaments when a muscle is relaxed.
Answer: FALSE
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
6) According to the sliding filament mechanism, during a muscle contraction, myosin pulls actin filaments toward the center of a sarcomere, causing the entire sarcomere to shorten.
Answer: TRUE
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
7) Fast-twitch fibers contain large amounts of myoglobin and predominate in “red” muscle.
Answer: FALSE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
8) Slow-twitch fibers contain many mitochondria and are well supplied with blood vessels, and can make ATP as they need it.
Answer: TRUE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
9) Isometric contractions usually result in no movement of the skeleton or objects.
Answer: TRUE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
10) The “all-or-none principle” states that in a given muscle, all of the cells are contracting simultaneously or none of them is contracting.
Answer: FALSE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
11) Tetanus results from a state of maximum muscle relaxation, which is necessary to allow the muscle to rest before the next contraction.
Answer: FALSE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
12) In the absence of ATP, a contracted muscle can’t relax.
Answer: TRUE
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
13) Following running for a long distance, the muscle soreness that occurs the next day is due to chemicals released to repair damaged muscles.
Answer: TRUE
Topic: Health & Wellness
Skill: Knowledge/Comprehension
14) Muscles of the hand contain a high percentage of fast-twitch fibers, which allows for actions that are strong and quick.
Answer: TRUE
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
15) Unlike skeletal muscle, cardiac and smooth muscle do not respond at all to the nervous system, but contract on their own. Differences in the rate of contraction of smooth and cardiac muscle are due to the action of pacemakers in cardiac muscles.
Answer: FALSE
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
16) Muscle soreness several days after exercise is an indication that some sarcomeres were permanently damaged.
Answer: TRUE
Topic: Health & Wellness
Skill: Knowledge/Comprehension
6.3 Matching Questions
Match each disorder or disease of the muscular system with its description.
- A) muscular dystrophy
- B) fasciitis
- C) tetanus
- D) muscle cramps
1) inflammation of the connective tissue layers surrounding a muscle; common in the sole of the foot
Topic: Sec. 6.5
Skill: Knowledge/Comprehension
2) a group of muscular diseases that are hereditary; resulting in muscle wasting; no cure
Topic: Sec. 6.5
Skill: Knowledge/Comprehension
3) disease caused by a bacterial infection; bacterial toxin affects primarily the muscles of the jaw and neck; also known as “lockjaw”
Topic: Sec. 6.5
Skill: Knowledge/Comprehension
4) uncontrolled contraction of muscle, usually after heavy exercise
Topic: Sec. 6.5
Skill: Knowledge/Comprehension
Answers: 1) B 2) A 3) C 4) D
Match the following.
- A) fatigue
- B) contraction
- C) twitch
- D) intercalated discs
- E) latent period
- F) slow-twitch fibers
- G) relaxation
- H) recruitment
- I) fast-twitch fibers
5) Sarcomere lengthens as calcium is returned to sarcoplasmic reticulum, and the troponin-tropomyosin complex attaches to myosin binding sites on actin.
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
6) time between the stimulation of a muscle and the beginning of a muscle contraction
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
7) Actin filaments slide over myosin filaments, and the sarcomere shortens.
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
8) aerobically break down fatty acids and glucose
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
9) contain gap junctions that permit rapid electrical stimulation of muscle cells
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
10) anaerobically break down creatine phosphate
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
11) decline in muscle activity as ATP levels decrease
Topic: Sec. 6.3
Skill: Understanding
12) complete cycle of contraction and relaxation
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
13) increases muscle force by activating more motor units
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
Answers: 5) G 6) E 7) B 8) F 9) D 10) I 11) A 12) C 13) H
Using the figure above, identify the parts of the sarcomere.
- A) sarcomere
- B) actin filament
- C) myosin filament
- D) Z-line
14) Label A represents a(n) ________.
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
15) Label B represents a(n) ________
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
16) Label C represents a(n) ________.
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
17) Label D represents a(n) ________.
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
Answers: 14) D 15) C 16) A 17) B
Match the following muscles to their function.
- A) quadriceps
- B) gastrocnemius
- C) external oblique
- D) biceps brachii
- E) triceps brachii
- F) trapezius
- G) tibialis anterior
- H) deltoid
18) bends forearm at elbow
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
19) causes lateral rotation of the trunk and abdominal compression
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
20) flexes thigh at the hip; extends leg at knee
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
21) flexes foot toward knee
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
22) raises arm
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
23) lifts and braces shoulders; draws head back
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
24) extends forearm at elbow
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
25) bends lower leg at knee and foot away from ankle
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
Answers: 18) D 19) C 20) A 21) G 22) H 23) F 24) E 25) B
Using the figure above and labels T through Z below, identify the structures indicated.
- A) fascicle
- B) muscle fiber
- C) tendon
- D) whole muscle
26) Structure A is a(n) ________.
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
27) Structure B is a(n) ________.
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
28) Structure C is a(n) ________.
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
29) Structure D is a(n) ________.
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
Answers: 26) C 27) B 28) A 29) D
6.4 Short Answer Questions
1) We are unable to exert any conscious control over the contraction of smooth or cardiac muscle. These muscles are referred to as ________ muscle.
Answer: involuntary
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
2) Since contraction of the hamstrings causes the knee to bend and contraction of the quadriceps causes the knee to extend, these muscles are said to be ________.
Answer: antagonistic
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
3) A muscle is arranged in bundles of muscle fibers, called ________.
Answer: fascicles
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
4) The contractile proteins that are located in myofibrils are called ________ and ________.
Answer: actin, myosin
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
5) The portion of a myofibril from one Z-line to the next is a(n) ________.
Answer: sarcomere
Topic: Sec. 6.1
Skill: Knowledge/Comprehension
6) The region where a skeletal muscle cell and a motor neuron come into close proximity to one another is the ________.
Answer: neuromuscular junction
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
7) Contraction of skeletal muscle is caused by the release of neurotransmitters from ________ neurons.
Answer: motor
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
8) The neurotransmitter, ________, has an excitatory effect on skeletal muscle, causing it to contract.
Answer: acetylcholine
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
9) The electrical impulse generated by a muscle cell membrane is transmitted to the sarcoplasmic reticulum by ________.
Answer: T (transverse) tubules
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
10) In the absence of calcium, myosin cannot contact actin because of the presence of the ________ covering the myosin binding sites on actin.
Answer: troponin-tropomyosin complex
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
11) To minimize muscle stiffness and soreness, undertake a new exercise activity in ________ for the first few days.
Answer: moderation
Topic: Health & Wellness
Skill: Knowledge/Comprehension
12) In order for fast-twitch muscle fibers to produce ATP, a phosphate from the high-energy molecule ________ is transferred to ADP.
Answer: creatine phosphate
Topic: Sec. 6.2
Skill: Application/Analysis
13) A student, who was late for class, bounded up four flights of steps, ran down the hall, and then arrived in his classroom, huffing and puffing. This student was breathing hard in order to reverse his body’s ________.
Answer: oxygen debt
Topic: Sec. 6.2
Skill: Application/Analysis
14) During a workout session, you may begin to experience a burning sensation in a muscle group that you are targeting with your choice of exercises. This is most likely due to anaerobic metabolism in that muscle, generating ________.
Answer: lactic acid
Topic: Sec. 6.2
Skill: Application/Analysis
15) The most common reason for muscle fatigue is the lack of enough ________ to meet the metabolic demands placed on the muscle.
Answer: ATP
Topic: Sec. 6.2
Skill: Knowledge/Comprehension
16) A protein that stores oxygen in slow-twitch muscle fibers is ________.
Answer: myoglobin
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
17) The process of activating more motor units when more force must be exerted is called ________.
Answer: recruitment
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
18) The ability to maintain an upright position is due to ________ muscle contractions.
Answer: isometric
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
19) As the rate of stimulation of motor units of a muscle increases, muscle force increases. This process is known as ________.
Answer: summation
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
20) The mechanical force that is generated when a muscle contracts is known as ________.
Answer: muscle tension
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
21) According to the ________ principle, a muscle cell contracts completely when adequately stimulated by a motor neuron.
Answer: all-or-none
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
22) Activities associated with aerobic training result in an increase in the amount of ________ in the body.
Answer: oxygen
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
23) A complete cycle of contraction and relaxation of muscle cells due to stimulation by a motor neuron is called a muscle ________.
Answer: twitch
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
24) The swinging of a tennis racket is a brief, high-intensity activity that requires the contraction of ________ fibers.
Answer: fast-twitch
Topic: Sec. 6.3
Skill: Knowledge/Comprehension
25) Cells in cardiac muscle that determine the rate of contraction are ________ cells.
Answer: pacemaker
Topic: Sec. 6.4
Skill: Knowledge/Comprehension
6.5 Essay Questions
1) What is the role of calcium ions during contraction of a skeletal muscle?
Answer: At rest, calcium ions are stored in the sarcoplasmic reticulum. Once the muscle cells have been stimulated or excited, calcium ions are released into the area of the contractile proteins. The ions bind to troponin, which results in a shift in position of the troponin-tropomyosin complex. This is necessary to expose the myosin binding sites on the actin molecule. Once exposed, the myosin heads can bind to the actin and cause the filaments to slide relative to each other, shortening the sarcomere.
Topic: Sec. 6.2
Skill: Understanding
2) If your goal was to become an endurance athlete, what type of training should you select, and why, to increase performance?
Answer: An endurance athlete depends on muscle efficiency to achieve increased performance and to complete a long-duration activity. The muscle fibers most useful to endurance events are slow-twitch. Aerobic training is needed, that is, activities that promote increased intake of oxygen to meet the muscle’s increased oxygen demands.
Topic: Sec. 6.3
Skill: Application/Analysis
Human Biology, 7e (Johnson)
Chapter 7 Blood
7.1 Multiple Choice Questions
1) All of the following are ways in which blood functions to maintain homeostasis in the human body EXCEPT which one?
- A) moving carbon dioxide away from cells following completion of aerobic metabolism
- B) conducting action potentials that originate in the nervous system to help with cell-cell communication
- C) transporting amino acids and other nutrients derived from digestion to all tissues in the body
- D) transporting hormones and other chemical messengers throughout the body from their point of secretion to their targets
- E) regulating the pH of body fluids
Answer: B
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
2) About 55% of whole blood is ________, which is/are mostly made up of water.
- A) plasma
- B) hemoglobin
- C) white blood cells
- D) clotting proteins
- E) hematocrit
Answer: A
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
3) Albumin proteins in human blood function
- A) to initiate blood clotting
- B) to transport oxygen to target cells
- C) to maintain blood volume
- D) as electrolytes
- E) to attack foreign organisms that enter the blood
Answer: C
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
4) Albumin, alpha globulin, beta globulin, and gamma globulin are all examples of
- A) plasma proteins
- B) antibodies
- C) white blood cells
- D) clotting factors
- E) hormones
Answer: A
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
5) When oxygen availability drops, certain cells in the kidney respond by producing erythropoietin, which in turn stimulates an increase in red blood cells. This cellular response represents
- A) the clotting mechanism
- B) negative feedback
- C) positive feedback
- D) all-or-none response
- E) aerobic metabolism
Answer: B
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
6) Which one of the following is a component of blood plasma?
- A) collagen
- B) hemoglobin
- C) bone
- D) water
- E) mitochondria
Answer: D
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
7) When the hormone erythropoietin is released in response to low oxygen levels, where is it transported to stimulate red blood cell production?
- A) kidney
- B) spleen
- C) red bone marrow
- D) liver
- E) throughout plasma
Answer: C
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
8) An increased risk for cardiovascular health problems is associated with
- A) an elevated level of hemoglobin
- B) high blood levels of HDLs
- C) decreased production of albumins
- D) high blood levels of LDLs
- E) low blood levels of LDLs
Answer: D
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
9) Which one of the following population of cells is most markedly increased during bacterial infections?
- A) neutrophils
- B) red blood cells
- C) platelets
- D) lymphocytes
- E) monocytes
Answer: A
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
10) Histamine is released from which one of the following types of leukocyte to stimulate the inflammatory response?
- A) lymphocyte
- B) basophil
- C) eosinophil
- D) neutrophil
- E) monocyte
Answer: B
Topic: Sec. 7.1
Skill: Knowledge/Comprehension
