3_Ch 6, chapter questions

Question 1

Bones don’t begin with bone tissue. what do they begin with?

Answer 1

Bones begin as fibrous membranes or hyaline cartilages.

Question 2

When describing endochondral ossification, some say “bone chases cartilage.” What does that mean?

Answer 2

The cartilage model grows, then breaks down and is replaced by bone.

Question 3

Where is the primary ossification center located in a long bone? Where is (are) the secondary ossification center/s located?

Answer 3

The primary ossification center in a long bone is in the center of the shaft. The secondary ossification center care in the epiphyses (bone ends).

Question 4

As a long bone grows in length, what is happening in the hypertrophic zone of the epiphyseal plate?

Answer 4

The chondrocytes are enlarging and their lacunar are breaking down and leaving holes in the cartilage matrix.

Question 5

What would happen to a bone if you removed all of the inorganic components (for example, by soaking it in vinegar for several days)? Would it be able to resist compression? tension?

Answer 5

Because acidic vinegar soaks away a bone’s mineral salts, the bone becomes flexible and bends too easily to support weight, so it would not be good resisting compression; However, its organic components, particularly collagen, would allow it to resist tension.

Question 6

Draw a cross section midway along the diaphysis of a typical long bone in an adult (omit any spongy bone). Label the medullary cavity and indicate the type of marrow found in this cavity. Label the compact bone. Draw and label the periosteum and endosperm.

Answer 6

draw

Question 7

Which cell has a ruffled border and acts to break down bone matrix? From your knowledge of organelles (chapter 3), state which organelle would be the likely source of the enzymes that can digest bone matrix.

Answer 7

The osteoclast fits this description. The lysosomes would contain the matrix-digesting enzymes.

Question 8

Which type of cartilage is most plentiful in the adult body?

Answer 8

Hyaline cartilage is the most plentiful in the adult body

Question 9

What two body structures contain flexible elastic cartilage?

Answer 9

The epiglottis and external ear cartilages are flexible elastic cartilage.

Question 10

Cartilage grows by interstitial growth. What does this mean?

Answer 10

Interstitial growth is growth from within.

Question 11

What is the functional relationship between skeletal muscles and bones?

Answer 11

Skeletal muscles use bones as levers to cause movement of the body and its parts.

Question 12

List two types of substances stored in bone and state where each is stored.

Answer 12

Bone matrix stores minerals (calcium and phosphate). Bone marrow cavities serve as sites for triglyceride (fat) storage.

Question 13

What are the components of the axial skeleton?

Answer 13

The components of the axial skeleton are the skull, the vertebral column, and the rib cage.

Question 14

Contrast the general function of the axial skeleton to that of the appendicular skeleton.

Answer 14

The major function of the axial skeleton is to establish the long axis of the body and to protect structures that it encloses. The general function of the appendicular skeleton is to allow us mobility for propulsion and manipulation of our environment.

Question 15

What bone class do the ribs and skull bones fall into?

Answer 15

The ribs and skull bones are flat bones.

Question 16

In the figure below (p. 184) name the parts of the bone indicated by a and b, and membranes found at c and d. What kind of cartilage is found at e? is this bone from an adult or a child? How can you tell?

Answer 16

The parts of the bone are:
1) epiphysis (a) and diaphysis (b). The membranes at C and d are the endosperm and periosteum, respectively. The cartilage at 2 is articular cartilage, which is hyaline cartilage. This bone is from an adult. (page 184)

Question 17

Which stimulus–PTH (a hormone) or mechanical forces acting on the skeleton–is more important in maintaining homeostasis blood calcium levels?

Answer 17

Parathyroid hormone maintains blood calcium levels.

Question 18

How do bone growth and bone remodeling differ?

Answer 18

Bone growth increases bone mass, as during childhood or when exceptional stress is placed on bones. Bone remodeling follows bone growth to maintain proper proportions of the bone considering stresses placed on it.

Question 19

If osteoclasts in a long bone are more active than osteoblasts, how will bone mass change?

Answer 19

If bone-destroying cells (osteoclasts) are more active than bone-forming cells (osteoblasts), bone mass will decrease.

Question 20

Apply daily exercise, the bones of astronauts in the international Space Station get thinner and weaker during their time in space. Why does this occur?

Answer 20

The bones of astronauts get thinner and weaker because they are deprived of the normal loading stresses that are placed on bones by gravity. Exercise that puts more stress on the bones during space flight helps to some extent but cannot substitute for gravity.

Question 21

How does an open fracture differ from a closed fracture?

Answer 21

In an open fracture, the bone ends are exposed to the external environment. In a closed fracture, the bone ends do not penetrate the external boundary of the skin.

Question 22

Which bone disorder is characterized by excessive deposit of weak poorly mineralized bone?

Answer 22

Paget’s disease is characterized by excessive deposit of weak, poorly mineralized bone.

Question 23

What are three measures that may help to maintain healthy bone density?

Answer 23

Sufficient vitamin D, calcium, and weight-bearing exercise all help to maintain healthy bone density.

Question 24

What name is given to adult “rickets”?

Answer 24

Adult rickets is called osteomalacia.

Question 25

What are the steps in endochondral ossification in a long bone?

Answer 25

a) a bone collar forms around the diaphysis of the hyaline cartilage model;
b) cartilage in the center of the diaphysis calcifies and then develops cavities;
c) the periosteal bud invades the internal cavities and spongy bone forms;
d) the diaphysis elongates and a medullary cavity forms. Secondary ossification centers appear in the epiphyses; and
e) the epiphyses ossify

Question 26

Which is NOT a function of the skeletal system? a) support, b) hematopoietic site, c) storage, d) providing levers for muscle activity, e) generating heat

Answer 26

e

Question 27

Sites of hematopoiesis include all but a) red marrow, b) the heads of femur and humerus in adults, c) medullary cavities in bones of infants, d) medullary cavities in bones of a healthy adult

Answer 27

d

Question 28

The organic portion of matrix is important in providing all but a) tensile strength, b) harness, c) ability to resist stretch, d) flexibility

Answer 28

b

Question 29

Bone remodeling in adults is regulated and directed mainly by a) growth hormone, b) thyroid hormones, c) sex homones, d) mechanical stress, e) PTH

Answer 29

d, e

Question 30

Where within the epiphyseal plate are the dividing cartilage cells located? a) between the calcification zone and the ossification zone, b) between the hypertrophic zone and the calcification zone, c) between the resting zone and the hypertrophic zone, d) in the primary ossification center.

Answer 30

c

Question 31

Wolff’s law is concerned with a) calcium homeostasis of the blood, b) the shape of a bone being determined by mechanical stresses placed on it, c) the electrical charge on bone surfaces

Answer 31

b

Question 32

Formation of the bony callus in fracture repair is followed by a) hematoma formation, b) fibrocartilaginous callus formation, c) bone remodeling, d) formation of granulation tissue

Answer 32

c

Question 33

The fracture type in which the bone ends are incompletely separated is a) greenstick, b) compound, c) simple, d) comminuted, e) compression

Answer 33

a

Question 34

The disorder in which bones are porous and thin but bone composition is normal a) osteomalacia, b) osteoporosis, c0 Paget’s disease

Answer 34

b