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90 terms

Chapter 6

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STUDY
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Which of following is a function of the skeletal system?
A) body support
B) calcium homeostasis
C) protection of internal organs
D) blood cell production
Which of the following are not components of the skeletal system?
tendons
Which of the following bones is classified as "irregular" in shape?
vertebra
The tip of a long bone is called the
epiphysis
The carpal bones are examples of ________ bones
short
A rib is an example of a ________ bone.
flat
Bones that develop within tendons are called ________ bones.
sesamoid
Small, oddly shaped bones that fill gaps between bones of the skull are called ________ bones.
sutural
________ bones develop inside tendons, commonly near the knees, hands, and feet.
Sesamoid
The humerus is an example of a(n) ________ bone.
long
The large proximal projection on the femur is termed the
trochanter
A hole through a bone is termed a
foramen
The smooth, rounded articular process of a bone is termed a
condyle
A shallow depression on a bone is termed a
fossa
The region of a long bone between the end and the shaft is known as the ________.
metaphysis
Which of the following labels best matches osteocyte?
mature bone cell
Bone is composed of ________ percent cells.
2
Cells that secrete the organic components of the bone matrix are called
osteoblasts
________ are squamous stem cells that develop into osteoblasts.
Osteoprogenitor cells
Through the action of osteoclasts
bony matrix is dissolved.
The space occupied by an osteocyte is called a
lacuna
Which of the following chemicals is not present in bone?
chondroitin sulfate
________ account(s) for almost two-thirds of the weight of bone.
Calcium phosphate
________ cells are located in the inner cellular layer of the periosteum.
Osteoprogenitor
The ________ interactions allow bone to be strong, somewhat flexible, and highly resistant to shattering.
protein-crystal
The most abundant cell type in bone is
osteocytes.
The lacunae of osseous tissue contain
osteocytes
How would removing hydroxyapatite from bone matrix affect the physical properties of a bone?
The bone would be more flexible.
The narrow passageways that contain cytoplasmic extensions of osteocytes
canaliculi.
The central canal of an osteon contains
blood vessels.
The interconnecting tiny arches of bone tissue found in spongy bone are called
osteons
The type of bone that is adapted to withstand stresses that arrive from many directions is ________ bone.
spongy
The structural units of mature compact bone are called
osteons.
Fat is stored within the
medullary cavity.
Which of the following is a characteristic of bone?
The bone matrix is very dense and contains deposits of calcium salts.
In relationship to the diaphysis of a long bone, the osteons are
parallel.
The femur can withstand ________ times the body weight without breaking.
10 to 15
________ marrow is found between the trabeculae of spongy bone.
red
The lining of the medullary cavity is called the
endosteum
________ bone reduces the weight of the skeleton and reduces the load on muscles.
Spongy
The layers of bone tissue immediately deep to the periosteum are
circumferential lamellae.
Which statement is true regarding calcium in bone matrix?
Calcium is found in crystals called hydroxyapatite.
The trabeculae of spongy bone
are organized along stress lines.
The articular cartilage of a typical long bone is composed of what type of cartilage?
hyaline
The deposition of calcium salts in bone tissues is referred to as
ossification
Which of the following is formed by intramembranous ossification?
the roof of the skull and the clavicle
Endochondral ossification begins with the formation of a(n)
cartilage model.
The following are important steps in the process of endochondral ossification.
1. Enlarged chondrocytes die.
2. Osteoblasts replace calcified cartilage with spongy bone.
3. Chondrocytes enlarge and the surrounding matrix begins to calcify.
4. Blood vessels invade the perichondrium.
5. Perichondrial cells become osteoblasts and produce a thin shell of bone.

The correct order for these events is
3,1,4,5,2
Secondary ossification centers occur
in the epiphyses.
Intramembranous ossification begins with differentiation of ________ cells.
mesenchymal
Which of the following statements about Marfan's syndrome is false?
results in short, stubby fingers
Bone growth in length occurs by mitosis of
cartilage cells in the epiphyseal side of the metaphysis.
Intramembranous ossification
produces flat bones as in the bones of the roof of the skull.
Primary ossification centers develop in long bones in the
diaphysis.
Bone tissue formation begins when osteoblasts secrete
collagen fibers.
Suppose that epiphyseal lines appear in a 10-year-old's long bones. Which of the following statements is therefore true?
The epiphyseal plates have ossified and further growth in length is not possible.
During appositional growth
bones grow wider.
When the epiphyseal plate is replaced by bone,
long bones have reached their adult length.
When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, bones
grow longer.
Accelerated closure of the epiphyseal plates could be caused by
elevated levels of estrogen
When production of sex hormones increases at puberty, epiphyseal plates
become narrower.
The following are major steps in the process of intramembranous ossification:
1. Clusters of osteoblasts form osteoid that becomes mineralized.
2. Osteoblasts differentiate within mesenchymal connective tissue.
3. Spicules of bone radiate out from the ossification centers.
4. Mesenchymal cells aggregate.
4,2,1,3
In normal adult bones,
a portion of the protein and mineral content is replaced each year
A lack of exercise could
result in porous and weak bones.
When stress is applied to a bone,
the minerals in the bone produce a weak electrical field that attracts osteoblasts.
Excessive growth hormone prior to puberty could result in
giantism.
Factors that are necessary for proper bone formation include all of the following, except
vitamin E
Where in the body does the production of precursors for the synthesis of calcitriol occur?
skin
The most abundant mineral in the human body is
calcium
Elevated levels of calcium ion in the blood stimulate the secretion of the hormone
calcitonin.
The hormone calcitonin functions to
decrease the level of calcium ion in the blood
Parathyroid hormone functions in all of the following ways, except that it
inhibits calcitonin secretion.
A child with rickets often has
bowed legs
Bone plays a central role in the regulation of blood levels of
calcium.
Hundreds of years ago explorers often died of scurvy. How can this bone-related disease be prevented?
supplement the diet with fresh fruit rich in Vitamin C
How is vitamin D (vitamin D3) related to calcium homeostasis in bone?
Vitamin D is involved in calcium absorption by the digestive tract so calcium is available for ossification and remodeling.
The disease osteomalacia causes calcium loss from the skeleton, which would result in bones that are
weaker and more flexible.
After a fracture of the diaphysis has healed, the thickened region that results is called the
external callus.
A fracture at the ankle involving both lower leg bones is often called a ________ fracture.
Pott
While on a school skiing trip in Colorado, Heidi falls and breaks her tibia and fibula in a Pott fracture. What would you expect as a prominent part of her clinical assessment several hours after the fall?
hematoma
Put the following steps of bone repair in correct sequence:
1. Cartilage in the external callus is replaced by bone.
2. A hematoma occurs.
3. An internal callus forms at the site of injury.
4. Osteoclasts remodel the bone at the site of repair.
2,1,3,4
Osteoclast-activating factor does all of the following, except that it
is released in large amounts early in life.
A condition in which bone becomes riddled with holes is called
osteoporosis
The condition known as osteopenia
causes a gradual reduction in bone mass
If osteoclasts are more active than osteoblasts, bones will become
osteopenic
Why does osteoporosis affect more women than men?
Women have a decrease in sex hormones after menopause whereas men continue to produce male sex hormones throughout adulthood.
Aging has what effect on the skeletal system?
loss of calcium and collagen fibers from matrix
If a tumor secretes high levels of osteoclast-activating factor, which of the following would you expect to occur as a result of this condition?
increases in blood levels of calcium
bone fragility
decreased bone density
increased osteoclast activity
Mary is 50 years old and has entered menopause. During a checkup, a bone scan reveals the beginnings of osteoporosis. Her physician suggests hormone therapy. What hormone might she prescribe for her patient?
estrogen
Mary is 50 years old and has entered menopause. During a checkup, a bone scan reveals the beginnings of osteoporosis. Her physician suggests nutritional therapy. What might she recommend for her patient?
vitamin C
vitamin D
calcium supplements
dairy products