Pathophysiology: Chapter 44: Structure and Function of the Musculoskeletal System Flashcards
Which bone cells produce osteocalcin when stimulated by 1,25-dihydroxyvitamin D and
synthesize osteoid?
a. Osteoclasts c. Fibrocytes
b. Osteocytes d. Osteoblasts
ANS: D
Osteoblasts are cells derived from mesenchymal stem cells and produce several
substances, including osteocalcin, transforming growth factor–beta (TGF-) (a growth
inhibitor for many cells), macrophage colony–stimulating factor, receptor activator of
nuclear factor kappa-B ligand, osteoprotegerin (OPG), and bone matrix when stimulated
by 1,25-dihydroxyvitamin D. This statement is not true of the other options.
What happens to the original bone during the second phase of bone remodeling? a. The original bone is replaced. b. It hardens. c. The original bone is resorbed. d. It is synthesized. `
ANS: C
The distribution of these apoptotic osteocytes provides osteoclasts with information about
where to begin resorbing damaged bone. In the second phase of remodeling (resorption),
the osteoclasts form a cutting cone that gradually resorbs bone, leaving behind an
elongated cavity termed a resorption cavity. This selection is the only option that
accurately describes what happens when bone is resorbed.
Which cells function to maintain bone matrix?
a. Osteoclasts c. Osteoblasts
b. Osteocytes d. Osteophytes
ANS: B
Osteocytes help synthesize and replace needed elements of the matrix by signaling
osteoclasts and osteoblasts to resorb and form new bone. This selection is the only option
that performs that function.
Which bone cells are large and multinucleated and contain lysosomes filled with
hydrolytic enzymes?
a. Osteoblasts c. Osteocytes
b. Osteoclasts d. Fibrocytes
ANS: B
Osteoclasts are the major resorptive cells of bone. They are large multinucleated cells with
a short life span and contain lysosomes (digestive vacuoles) filled with hydrolytic
enzymes. This selection is the only option that is described in this manner.
Which bone cell secretes hydrochloric acid to help dissolve bone minerals and
collagenase, thus aiding in the digestion of collagen?
a. Osteocytes c. Osteoclasts
b. Osteoblasts d. Osteophytes
ANS: C
Only osteoclasts bind to the bone surface of cell attachment proteins called integrins. They
bring about resorption of bone by secreting hydrochloric acid and cathepsin K (a protease
enzyme) that help dissolve bone minerals and collagenase, which aids in digesting
collagen, along with the action of cytokines.
Which glucoprotein is believed to inhibit calcium phosphate precipitation and play a part
in bone resorption by recruiting osteoclasts?
a. Osteocalcin c. Laminin
b. Osteonectin d. Osteopontin
ANS: A
The roles of osteocalcin may be to inhibit calcium phosphate precipitation and play a part
in bone resorption by recruiting osteoclasts. This statement is not true of any other option.
Which glucoprotein is thought to transport essential elements such as hormones, ions, and
other metabolites to and from the bone cells?
a. Osteocalcin c. Laminin
b. Osteonectin d. Bone albumin
ANS: D
Researchers believe bone albumin transports essential elements such as hormones, ions,
and other metabolites to and from the bone cells and maintain the osmotic pressure of bone
fluid (fluid surrounding mineral crystals and osteoblasts). This statement is not true of any
other option.
How is the work function of a muscle usually calculated?
a. Muscle type
b. Calculating force X distance
c. Foot pounds
d. Kilograms
ANS: B
The ultimate function of muscle is to accomplish work. Although expressed in such
measures as foot-pounds or kilogram-meters, work refers to the amount of energy liberated
or the amount of force exerted over a distance (work = force X distance). Muscle type is
not relevant.
What is the basic structural unit in compact bone?
a. Small channels called canaliculi
b. Osteocytes within the lacunae
c. Tiny spaces within the lacunae
d. Haversian system
ANS: D
The basic structural unit in compact bone is the haversian system (see Figure 43-4). This
selection is the only option that accurately identifies the basic structure of compact bone.
Which part of an injured joint becomes insensitive to pain and regenerates slowly and
minimally?
a. Synovium c. Bursa
b. Articular cartilage d. Tendon
ANS: B
Articular cartilage has no blood vessels, lymph vessels, or nerves. Therefore it is
insensitive to pain and regenerates slowly and minimally after injury. These statements are
not true of the other options.
The outer layer of the periosteum contains blood vessels and nerves that penetrate the
inner structures of the bone by way of which structure?
a. Volkmann canals c. Sharpey canals
b. Canaliculi d. Trabeculae
ANS: A
All bones are covered with a double-layered connective tissue called the periosteum. The
outer layer of the periosteum contains blood vessels and nerves, some of which penetrate
to the inner structures of the bone only through channels called Volkmann canals (see
Figure 43-4).
What is the function of Sharpey fibers?
a. To anchor the outer layer of the periosteum to the inner layer
b. To contain blood vessels and nerves on the outer layer of the periosteum
c. To help attach tendons and ligaments to the periosteum
d. To attach muscles to the periosteum
.
ANS: C
Collagenous fibers (Sharpey fibers) that penetrate the bone anchor the inner layer of the
periosteum to the bone. Sharpey fibers help hold or attach tendons and ligaments, not
muscle, but to the periosteum of bones
After puberty, the epiphyseal plate calcifies, and the epiphysis merges with the
__________.
a. Epiphyseal line c. Metaphysis
b. Epiphyseal plate d. Articular cartilage
ANS: C
After puberty, the epiphyseal plate calcifies and the epiphysis merges only with the
metaphysis.
The stage of healing in the bone that involves procallus formation entails which process?
a. Formation of a hematoma that allows the development of a fibrin network
b. Production of granulation tissue by fibroblasts, capillary buds, and osteoblasts
c. Development of a primitive bone matrix termed woven bone
d. Remodeling of the periosteal and endosteal bone surfaces
ANS: B
Fibroblasts, capillary buds, and osteoblasts move into the wound to produce granulation
tissue called a procallus. None of the other options are associated with this process.
Which term describes a freely movable joint?
a. Synarthrosis c. Biarthrosis
b. Amphiarthrosis d. Diarthrosis
ANS: D
Based on movement, a joint is classified as a synarthrosis (immovable joint), an
amphiarthrosis (slightly movable joint), or a diarthrosis (freely movable joint). Biarthrosis
is not a term used to describe a freely movable joint.
Which type of joint holds teeth in the maxilla or mandible?
a. Amphiarthrosis c. Synarthrosis
b. Diarthrosis d. Gomphosis
ANS: D
A gomphosis is a special type of fibrous joint in which a conical projection fits into a
complementary socket and is held in place by a ligament. Gomphosis is the only term used
to identify the joint that holds teeth in the maxilla or mandible.
The hyaline cartilage joints between the ribs and sternum are examples of which type of
joint?
a. Synchondrosis c. Gomphosis
b. Symphysis d. Syndesmosis
ANS: A
A synchondrosis is the only type of joint in which hyaline cartilage, rather than
fibrocartilage, connects the two bones. The joints between the ribs and the sternum are
synchondroses and are not examples of any of the other types.
The joint that contains a synovial membrane that lines the inner joint capsule is an
example of which type of joint?
a. Amphiarthrosis c. Synarthrosis
b. Diarthrosis d. Biarthrosis
ANS: B
The joint that contains a synovial membrane that lines the inner joint capsule is a
diarthrosis. A synovial joint consists of the following parts: (1) fibrous joint capsule
(articular capsule), (2) synovial membrane that lines the inner surface of the joint capsule,
(3) joint cavity (synovial cavity or space formed by the capsule), (4) synovial fluid, which
fills the joint cavity and lubricates the joint surface, and (5) articular cartilage, which
covers and pads the articulating bony surfaces.
What is the function of the synovial membrane’s type A cells within the intima?
a. To release mast cells, initiating the inflammatory process after joint injury
b. To ingest and remove bacteria and debris by phagocytosis in the joint cavity
c. To secrete hyaluronate, a binding agent that gives synovial fluid its viscous quality
d. To store fat cells and glycogen, providing adenosine triphosphate for joint activity
ANS: B
The intima contains two types of synovial cells: A and B. Type A synovial cells ingest and
remove bacteria and particles of debris by phagocytosis in the joint cavity. None of the
remaining options accurately describes the function of the synovial membrane’s type A
cells.
Which statement does not present accurate information concerning synovial fluid?
a. Synovial fluid contains protein polysaccharides to repair the synovial membrane
after injury.
b. It lubricates the joint surfaces.
c. Synovial fluid nourishes the pad of the articular cartilage.
d. It contains leukocytes to phagocytize joint debris and microorganisms.
ANS: A
Synovial fluid lubricates the joint surfaces, nourishes the pad of the articular cartilage that
covers the ends of the bones, and contains free-floating synovial cells and various
leukocytes that phagocytose joint debris and microorganisms. The other options provide
accurate information about synovial fluid.
What anchors articular cartilage to the underlying bone?
a. Sharpey fibers c. Glycoproteins
b. Collagen fibers d. Elastin fibers
ANS: B
Collagen fibers are important components of the cartilage matrix because they anchor the
cartilage securely to underlying bone. This statement is not true of the other options.
What controls the movement of synovial fluid through cartilage?
a. Cartiloregulins c. Proteoglycans
b. Hyaluronate d. Chondroitin
ANS: C
Only proteoglycans give articular cartilage its stiff quality and regulate the movement of
synovial fluid through the cartilage.
Which statement is false about muscles?
a. Muscle comprises 50% of an adult’s body weight and 40% of a child’s body
weight.
b. Muscle is 75% water, 20% protein, and 5% organic and inorganic compounds.
c. Muscle contains 32% of all protein stores for energy and metabolism.
d. Muscles are encased in fascia.
.
ANS: A
Muscle constitutes 40% of an adult’s body weight and 50% of a child’s body weight. The
other options are true statements regarding muscles
Which characteristic is true of type II (white fast-motor) muscle fibers?
a. Slow contraction speed
b. Fast conduction velocities
c. Profuse capillary supply
d. Oxidative metabolism
ANS: B
Type II fibers, also called white fast-motor fibers, are innervated by relatively large type II
alpha motor neurons with fast conduction velocities. This selection is the only correct
option provided.
As the innervation ratio of a particular organ increases, what other property also increases?
a. Control c. Coordination
b. Movement d. Endurance
ANS: D
The greater the innervation ratio of a particular organ, the greater is its endurance.
Low-innervation ratios promote control and coordination, whereas high ratios promote
strength and endurance. An increase in the innervations ratio does not result in an increase
in movement.
Which statement describes a neuroregulin?
a. Chemical mediator that initiates signals from the anterior horn cell of the spinal
card to the axon of motor nerve branches of groups of muscle fibers
b. Neurotransmitter that provides a means of reporting changes in length, tension,
velocity, and tone in muscles
c. Proteoglycan secreted by neurons, which increases acetylcholine receptors
d. Mechanoreceptor that lies parallel to muscle fibers and responds to muscle
stretching
ANS: C
Motor and sensory neurons secrete a proteoglycan called neuroregulin that increases
acetylcholine receptors and helps in the formation of muscle spindle fibers. This selection
is the only option that accurately describes a neuroregulin.
Which four-step process correctly describes muscle contraction?
a. Coupling, contraction, relaxation, excitation
b. Contraction, relaxation, excitation, coupling
c. Relaxation, excitation, coupling, contraction
d. Excitation, coupling, contraction, relaxation
ANS: D
Muscle contraction is a four-step process: excitation, coupling, contraction, and relaxation.
Which type of ion directly controls the contraction of muscles?
a. Sodium c. Calcium
b. Potassium d. Magnesium
ANS: C
Contraction begins as the calcium ions combine with troponin, a reaction that overcomes
the inhibitory function of the troponin-tropomyosin system. This selection is the only
option that has such a direct association with muscle contraction.
In which type of contraction does the muscle maintain a constant tension as it moves?
a. Isotonic c. Hypertonic
b. Isometric d. Hypotonic
ANS: A
Only during an isotonic contraction does the muscle maintain a constant tension as it
moves.
Which term is used to identify a functional muscle contraction in which the muscle
contracts but the limb does not move?
a. Isotonic c. Eccentric
b. Isometric d. Concentric
ANS: B
Only during an isometric contraction (static or holding contraction) does the muscle
maintain a constant length as tension is increased. Isometric contraction occurs, for
example, when the arm or leg is pushed against an immovable object. The muscle
contracts, but the limb does not move.
Which statement is false about aging and the musculoskeletal system?
a. Haversian system erodes, the canals nearest the marrow cavity widened, and the
endosteal cortex converts to spongy bone.
b. The remodeling cycle increases because of a decreased ability of the basic
multicellular units to resorb and deposit bone.
c. Cartilaginous rigidity increases because of decreasing water content and
decreasing concentrations of glycosaminoglycans.
d. Muscle ribonucleic acid (RNA) synthesis declines, although the regenerative
function of muscle tissue is reportedly normal in older adults.
ANS: A
Aging does not typically have an effect on the haversian system as described. The
remaining options are accurate statements regarding the effects of aging.
Which component is found in synovial fluid?
a. Protein polysaccharides
b. Water
c. Leukocytes
d. Chondrocytes
ANS: C
Synovial fluid lubricates the joint surfaces, nourishes the pad of the articular cartilage that
covers the ends of the bones, and contains only free-floating synovial cells and various
leukocytes that phagocytose joint debris and microorganisms. None of the remaining
options are found in synovial fluid.
What term is used to identify an interlacing bundle of dense, white fibrous tissue that is
richly supplied with nerves, blood vessels, and lymphatic vessels?
a. Procallus c. Hematoma
b. Joint capsule d. Elastin fibers
ANS: B
The joint capsule is made up of parallel, interlacing bundles of dense, white fibrous tissue.
It is richly supplied with nerves, blood vessels, and lymphatic vessels. None of the other
options are associated with this structure.
