[Ex4] - C40 - AP

Question 1

40-1. Which component of the bone matrix gives bone its tensile strength?

a. Calcium
b. Phosphate
c. Collagen
d. Magnesium

Answer 1

ANS: C

While calcium, phosphate, and magnesium all play a role in bone formation, collagen is the
component of bone matrix that gives bone tensile strength.

Question 2

40-2. Once their initial function is complete, what do osteoblasts become?

a. Osteoclasts
b. Osteocytes
c. Chondroblasts
d. Osteoids

Answer 2

ANS: B

Osteoblasts are the bone-forming cells. Their primary function is to lay down new bone. Once
this function is complete, osteoblasts become osteocytes. Osteoclasts reabsorb bone.
Chondroblasts are a part of mature bone. Osteoids are part of nonmineralized bone matrix that
the osteoblasts work on.

Question 3

40-3. Hydroxyapatite found in bone matrix contains a combination of which molecules in its
crystalline structure?

a. Calcium and magnesium
b. Calcium and phosphate
c. Phosphate and magnesium
d. Magnesium and hydrogen

Answer 3

ANS: B

Calcium and phosphate form amorphous (fluid) calcium phosphate compounds that are
converted, in stages, to solid hexagonal crystals of hydroxyapatite. Hydroxyapatite does not
contain magnesium or hydrogen.

Question 4

40-4. What is the major difference between compact and spongy bone?

a. Organization of the structural elements
b. Location within the body
c. Activating chemicals in each
d. Types of minerals in the bone matrix

Answer 4

ANS: A

The major difference between the two types of tissue is the organization of the elements. The
differences in location in the body, chemical activation, or types of minerals contained are not
as relevant.

Question 5

40-5. How do blood vessels penetrate into the inner structures of the bone?

a. Volkmann canals
b. Canaliculi
c. Sharpey fibers
d. Lamellae

Answer 5

ANS: A

The outer layer of the periosteum contains blood vessels and nerves, some of which penetrate
to the inner structures of the bone through channels called Volkmann canals. Canaliculi are
small channels or canals. Sharpey fibers also help hold or attach tendons and ligaments to the
periosteum of bones. Concentric layers of bone matrix are called lamellae.

Question 6

40-6. After puberty, the epiphyseal plate calcifies, and the epiphysis and _____ merge.

a. epiphyseal line
b. diaphyseal plate
c. metaphysis
d. articular cartilage

Answer 6

ANS: C

After puberty, the epiphyseal plate calcifies, and the epiphysis and metaphysis merge. None of
the other options merges with the epiphysis after puberty.

Question 7

40-7. Clusters of which type of bone cells are responsible for bone remodeling?

a. Trabeculae
b. Osteoclastic cutting cones
c. Basic multicellular units
d. Haversian system cells

Answer 7

ANS: C

Remodeling is carried out by clusters of bone cells termed basic multicellular units. The basic
multicellular units are made up of bone precursor cells that differentiate into osteoclasts and
osteoblasts. Trabeculae are plates found in spongy bone. The osteoclasts form a “cutting
cone,” which gradually resorbs bone, not remodels it. Haversian canals are part of compact
bone.

Question 8

40-8. When describing a freely movable joint, which term should be used?

a. Synarthrosis
b. Amphiarthrosis
c. Fibrous
d. Diarthrosis

Answer 8

ANS: D

A diarthrotic joint is freely moveable. A synarthrotic joint is immovable. An amphiarthrotic
joint is slightly movable. A fibrous joint has little, if any, movement.

Question 9

40-9. A nurse recalls fibrous joints generally are:

a. rotating.
b. slightly movable.
c. freely movable.
d. calcified.

Answer 9

ANS: B

A fibrous joint has little, if any, movement.

Question 10

40-10. Which of the following should the nurse include when discussing the different types of
cartilaginous joints?

a. Sutures and gomphosis
b. Syndesmosis and gomphosis
c. Symphysis and synchondrosis
d. Gomphosis and synchondrosis

Answer 10

ANS: C

There are two types of cartilaginous joints: symphysis and synchondrosis.

Question 11

40-11. What type of joint normally exists between the teeth and the maxilla or mandible?

a. Symphysis
b. Diarthrosis
c. Gomphosis
d. Syndesmosis

Answer 11

ANS: C

Gomphosis joints exist between the teeth and the maxilla or mandible. None of the other
options fulfills that function.

Question 12

40-12. A nurse recalls the freely moveable joint is an example of which type of joint?

a. Amphiarthrosis
b. Diarthrosis
c. Synarthrosis
d. Symphysis

Answer 12

ANS: B

The elbow joint is freely moveable and is an example of a diarthrosis joint; amphiarthrosis
joints are only slightly moveable. Synarthrosis joints are immoveable. A symphysis is a
cartilaginous joint in which bones are united by a pad or disk of fibrocartilage.

Question 13

40-13. Between which structures will you find a joint that contains synchondrosis costal cartilage?

a. Vertebrae
b. Ribs and sternum
c. Sutures of the skull
d. Facial bones

Answer 13

ANS: B

Synchondrosis costal cartilage is located between the ribs and the sternum. This type of
cartilage is not found between the vertebrae, sutures of the skull, or between the facial bones.

Question 14

40-14. The skeletal muscles are encased in a connective tissue framework made of:

a. bone.
b. epithelium.
c. fascia.
d. cartilage.

Answer 14

ANS: C

Each skeletal muscle is a separate organ, encased in a three-part connective tissue framework
called fascia. This framework is not made of bone, epithelium, or cartilage.

Question 15

40-15. Which layer forms the fascicles in skeletal muscle?

a. Tendon sheath
b. Endomysium
c. Epimysium
d. Perimysium

Answer 15

ANS: D

The perimysium further subdivides the muscle fibers into bundles of connective tissue called
fascicles. None of the other options forms fascicles.

Question 16

40-16. Which characteristic of a postural muscle is a result of having substantial amounts of type I
muscle fibers?

a. Resists fatigue.
b. Rapid response time.
c. Little contractibility.
d. Lacks a fascia lining.

Answer 16

ANS: A

Postural muscles have more type I fibers, allowing them the high resistance to fatigue that is
necessary to maintain the same position for extended periods. The ocular muscles have more
type II muscle fibers, allowing them to respond rapidly to visual changes. Little contractibility
or lacking a fascia lining is associated with type I muscle fibers.

Question 17

40-17. The structure of the contractile subunit of the myofibril is called the:

a. sarcoplasmic reticulum.
b. actin.
c. motor end plate.
d. sarcomere.

Answer 17

ANS: D

The sarcomere is the contractile portion of the myofibril. In response to a nerve impulse,
RyR1 (found in skeletal muscle cells) releases intracellular calcium and initiates muscle
contraction at the sarcomere, a portion of the myofibril. The sarcoplasmic reticulum is made
like the endoplasmic reticulum in other cells. Actin is a protein of the sarcomere. It is at the
motor nerve end plate where the nerve impulse is transmitted.

Question 18

40-18. Which ions directly control the contraction of muscles?

a. Sodium
b. Potassium
c. Calcium
d. Magnesium

Answer 18

ANS: C

Contraction begins as the calcium ions combine with troponin, a reaction that overcomes the
inhibitory function of the troponin-tropomyosin system. The release of intracellular calcium
ions is the critical link between a nerve impulse (electrical excitation) and muscle contraction.
The critical link that allows for the contraction of muscles is not reliant upon sodium,
potassium, or magnesium.

Question 19

40-19. Which molecule prevents a muscle contraction from occurring when the muscle is at rest?

a. Calcium
b. Troponin-tropomyosin
c. Actin
d. Myosin

Answer 19

ANS: B

Contraction begins as the calcium ions combine with troponin, a reaction that overcomes the
inhibitory function of the troponin-tropomyosin system. Calcium, actin, and myosin all
facilitate muscle contraction.

Question 20

40-20. During which stage of muscle contraction does actin bind to myosin?

a. Coupling
b. Relaxation
c. Discharging
d. Excitation

Answer 20

ANS: A

During coupling, depolarization of the transverse tubules occurs. This triggers the release of
calcium ions from the sarcoplasmic reticulum, exposing binding sites on the actin molecule.
In the presence of calcium, actin is free to bind with myosin. Relaxation is the last step. It
begins as calcium ions are actively transported back into the sarcoplasmic reticulum,
removing ions from interaction with troponin. Discharging is not a step in the process.
Excitation is the first step of muscle contraction and it begins with the spread of an action
potential from the nerve terminal to the neuromuscular junction.

Question 21

40-21. What is the main energy source or fuel for skeletal muscle contraction?

a. Potassium
b. Lactic acid
c. Adenosine triphosphate (ATP)
d. Actin

Answer 21

ANS: C

Skeletal muscle requires a constant supply of ATP and phosphocreatine. These substances are
necessary to fuel the complex processes of muscle contraction. Neither potassium, lactic acid,
nor actin is the main energy source for muscle contraction.

Question 22

40-22. The nurse observed the patient’s muscle contracted, but the limb did not move. How should
the nurse chart this muscle contraction?

a. Isotonic contraction
b. Isometric contraction
c. Eccentric contraction
d. Concentric contraction

Answer 22

ANS: B

During isometric contraction, the muscle contracts, but the limb does not move. During
isotonic contraction, the muscle maintains a constant tension as it moves. Eccentric
contraction is a form of isotonic contraction. Concentric contraction is a form of isotonic
contraction.

Question 23

40-23. What term identifies a muscle acting as a contraction’s prime mover?

a. Flexor
b. Recruiter
c. Antagonist
d. Agonist

Answer 23

ANS: D

When a muscle contracts and acts as a prime mover, or agonist, its reciprocal muscle, or
antagonist, relaxes. Neither the term flexor nor recruiter identifies this action.

Question 24

40-24. What does the term “sarcopenia” describe?

a. Absence of muscle cells
b. Fatigue of muscle cells
c. Age-related loss in skeletal muscle
d. Muscles that are unable to contract

Answer 24

ANS: C

Age-related loss in skeletal muscle is referred to as sarcopenia and is a direct cause of the
age-related decrease in muscle strength. The term is not used to describe the absence or
fatigue of muscle cells or their inability to contract.