A&P CH. 6

Which step in the figure contains compact bone?

D. Osteoblasts in the periosteal layer form compact bone characteristic of the exterior surface of a mature bone.

Which of the labeled parts of the bone is composed primarily of compact bone?

D. The shaft of an adult long bone is composed of compact bone.

Short, irregular, and flat bones have medullary cavities in order to keep the weight of the bones light.

False

The periosteum is a tissue that serves only to protect the bone because it is not supplied with nerves or blood vessels.

False

What is the term for the layers of bony matrix surrounding the vessels and nerve?

Lamellae Lamellae are layers of bony matrix synthesized by osteoblasts during bone growth and maintenance.

An osteon contains osteocytes, lamellae, and a central canal, and is found in compact bone only.

True

Which of the following statements is true?

a. During endochondral ossification, hyaline cartilage is broken down and replaced with bone. b. Endochondral ossification leads to the formation of the clavicles and cranial bones. c. Endochondral ossification occurs within fibrous connective tissue membranes. d. Most bones in the body are formed by intramembranous ossification. a. During endochondral ossification, hyaline cartilage is broken down and replaced with bone. Endochondral ossification is the formation of bone within hyaline cartilage. Beginning late in the second month of development, this process uses hyaline cartilage "bones" formed earlier as models, or patterns, for bone construction. It is more complex than intramembranous ossification because the hyaline cartilage must be broken down as ossification proceeds. Most bones below the base of the skull form by endochondral ossification.

Which of the following are correctly matched?

a. compound fracture; the fractured bone ends penetrate the skin b. non-displaced fracture; the fractured bone ends are misaligned c. incomplete fracture; the bone is broken through d. linear fracture; the break is perpendicular to the bone's long axis a. compound fracture; the fractured bone ends penetrate the skin In a compound (open) fracture, the fractured bone ends penetrate the skin. Such open injuries carry a higher risk of infection.

Which of the following is the major component of the part of the bone labeled E?

adipose tissue Yellow bone marrow within the medullary cavity is composed primarily of adipose tissue (fat).

What would be the physical sign that a bone cannot continue longitudinal growth?

an epiphyseal line The epiphyseal plate is a zone of hyaline cartilage between the epiphysis and diaphysis of a long bone. When the cartilage is replaced with bone and the plate closes, the bone has reached its maximum length. This ossified remnant of the "growth plate" is called the epiphyseal line.

The figure represents a wedge-shaped section of which structural unit of bone?

an osteon The circular structural unit found within compact bone is termed the osteon, and consists of a central canal surrounded by layers of bone.

The process of bones increasing in thickness is known as ________.

appositional growth

The central (Haversian) canal that runs through the core of each osteon is the site of ________.

blood vessels and nerve fibers

Which structure is seen at the arrow?

bone collar A collar of ossified tissue forms around the bone in the early stages of ossification.

In the epiphyseal plate, cartilage grows ________.

by pushing the epiphysis away from the diaphysis

What tissue forms the model for endochondral ossification?

cartilage

A fracture in the shaft of a bone would be a break in the ________.

diaphysis

Which bone-forming process is shown in the figure?

endochondral ossification The figure illustrates a step in the embryonic formation of a bone from a cartilage model.

Which structure allows the diaphysis of the bone to increase in length until early childhood?

epiphyseal plate

Which of the following is implicated in osteoporosis in older women?

estrogen deficiency due to menopause

Which of the following is a bone marking described as a round or oval opening through a bone?

foramen

What is the first stage in the healing of a bone fracture?

formation of a hematoma This is the first stage in the healing of a bone fracture. In order, here are the stages of bone fracture healing: (1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, and (4) bone remodeling.

Growth of bones is controlled by a symphony of hormones. Which hormone is of greatest importance for bone growth during infancy and childhood?

growth hormone

Which of the following is the single most important stimulus for epiphyseal plate activity during infancy and childhood?

growth hormone

What kind of tissue is the forerunner of long bones in the embryo?

hyaline cartilage

What material makes up most of the structure at A?

hyaline cartilage The articular cartilage at the ends of long bones is formed from hyaline cartilage.

Lengthwise, long bone growth during infancy and youth is exclusively through ________.

interstitial growth of the epiphyseal plates

Ossification of the ends of long bones ________.

is produced by secondary ossification centers

At an archeological site you discover a bone that is cylindrical in shape, about one inch long and a quarter of an inch wide. Choose the correct classification.

long

The cell responsible for secreting the matrix of bone is the ________.

osteoblast

Classify the cells seen at the arrow in image A.

osteoblasts Osteoblasts ("bone makers") begin bone formation by secreting the bone matrix.

When an osteoblast becomes completely surrounded by its own matrix secretions it is referred to as a(n) ________.

osteocyte

Which of the following refers to a bone disorder found most often in the aged and resulting in the bones becoming porous and light?

osteoporosis Osteoporosis refers to groups of diseases in which bone resorption outpaces bone deposit. The bones become fragile and easily fractured. The composition of the matrix remains normal, but bone mass declines, and the bones become porous and light. Osteoporosis occurs most often in postmenopausal women.

Which hormone increases osteoclast activity to release more calcium ions into the bloodstream?

parathyroid hormone

The periosteum is secured to the underlying bone by ________.

perforating (Sharpey's) fibers

Which of the following correctly pairs the structure at C with its primary component?

periosteum; dense irregular connective tissue The periosteum is composed of dense irregular connective tissue along with a layer of simple squamous epithelium.

Osteoblasts __________.

secrete osteoid Osteoblasts are the bone-forming cells that produce new bone by secreting the components of the organic matrix, called osteoid. They also play a role in the calcification of osteoid to form the mature bone matrix.

Which of the following bones are NOT a part of the appendicular skeleton?

skull

The arrow in the figure is pointing to which of the following structures?

the epiphyseal plate During endochondral ossification, a distinct epiphyseal plate is formed at the boundary between primary and secondary ossification centers.

What is intramembranous ossification?

the formation of bone from within fibrous membranes The formation of bone by ossification centers within fibrous membranes is called intramembranous ossification.

Which of the following best describes the process shown in the figure?

the formation of bone in a membrane The figure illustrates the formation of new bones within a fibrous membrane ("intramembranous") during embryonic development.

Spongy bone contains ________.

trabeculae

Choose which bone marking type would likely increase in size when a weight lifter repeatedly exercises muscles that attach to it.

trochanter

Which of the following is a site for a muscle or ligament attachment?

trochanter A trochanter is a type of bone projection; projections often protrude from the bone because of the interaction forced upon them by muscle or ligaments.

Your patient is returning for follow-up 6 weeks after sustaining a nondisplaced fracture of his radius. He tells you that his forearm is no longer painful, but he is concerned that he can palpate a "lump" in the bone at the site of the healing fracture. What is your response?

"That bump is a normal part of bone healing at this stage. As your body completes the process, the cells in your bone will gradually remodel it to its previous shape." Right! You understand the stages of bone healing, including the formation of callus and ultimate remodeling.

The term osteoid refers to the organic part of the matrix of compact bones without mineralization.

True

The collagen fibers of the osteoid make the overall bone matrix stronger by allowing it to resist bending and twisting forces.

True The organic matrix, or osteoid, makes up about one-third of the bone matrix. This portion includes the collagen fibers that provide bone with its flexibility and tensile strength, allowing it to resist stretch and twisting.

During infancy and childhood, the most important stimulus of epiphyseal plate activity is __________.

growth hormone During infancy and childhood, the single most important stimulus for bone growth is growth hormone. It directly stimulates growth of the hyaline cartilage that forms the epiphyseal plates in long bones, causing the bones to lengthen.

The correct order (from start to finish) of fracture repair is __________.

hematoma formation, soft callus formation, bony callus formation, and bone remodeling From start to finish, a fracture is repaired by (1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, and (4) bone remodeling.

The area where blood vessels are penetrating the center of the bone used to be occupied by which tissue?

hyaline cartilage In this type of ossification, the bone is first modeled from cartilage and then replaced by bone as blood vessels invade the model.

A homeostatic imbalance that activates these bone cells would lead to a loss of bone density.

osteoclasts Osteoclasts are the bone cells that break down bone. If they were activated more than normal, you should expect to see bone loss.

What type of cell is shown at A?

osteocyte Osteocytes, literally "bone cells," are the primary structural and maintenance cells found in bone.

What is the structural unit of compact bone?

osteon The structural unit of compact bone is the osteon, an elongated cylinder oriented parallel to the long axis of the bone.

Which of the following is a characteristic of the bone material at D but NOT of the material at B?

osteons The compact bone at D contains osteons. The spongy bone at B contains trabeculae but no osteons.

In which of the labeled parts of the adult long bone would hematopoietic tissue be located?

B. Hematopoietic tissue is found in the red bone marrow within certain body locations consisting of spongy bone. Examples include the diploe of flat bones and the proximal epiphyses of the femur and humerus (pictured).

For intramembranous ossification to take place, which of the following is necessary?

Ossification centers form in the fibrous connective tissue membrane.

Which statement regarding the classification of bones is FALSE?

a. Irregular bones include the vertebrae and hip bones. b. Long bones include all limb bones except the patella. c. The sternum is an example of a flat bone. d. Sesamoid bones form within certain tendons. b. Long bones include all limb bones except the patella. This is false; long bones include all limb bones except the patella, tarsals, and carpals.

Which statement regarding osteons is FALSE?

a. Osteons consist of concentric lamellae surrounding a central canal. b. Collagen gives osteons the ability to resist twisting forces. c. Osteons are found in all bone tissues d. The inorganic matrix of an osteon gives it the ability to resist compression. c. Osteons are found in all bone tissues Osteons are found only in compact bone; they are absent in spongy bone.

Which of the following statements regarding the skeleton is INCORRECT?

a. The appendicular skeleton includes the shoulder girdles. b. The axial skeleton includes the bones of the limbs. c. The appendicular skeleton allows us to move around. d. The axial skeleton supports and protects internal organs. b. The axial skeleton includes the bones of the limbs. The bones of the limbs makeup the appendicular skeleton.

Which of the following cells are NOT matched with their appropriate function?

a. bone lining cells; maintain bone matrix b. osteoclasts; bone resorption c. osteoblasts; create new bone matrix d. osteocytes; produce new bone cells. d. osteocytes; produce new bone cells. Osteocytes are mature bone cells that monitor and repair mature bone tissues.

Which of the following is NOT a function of the skeletal system?

a. communication b. support c. production of blood cells (hematopoiesis) d. storage of minerals a. communication

Cell division of chondrocytes occurs on the epiphysis facing side. Rather than dividing, here chondrocytes hypertrophy and deteriorate along the diaphyseal surface of the growth plate.

appositional growth Growth in width involves the adding of layers of lamellar (compact) bone along the bone's outer surface. This process of growth by "layering" is termed appositional growth and is distinct from growth by expansion of the interior matrix (interstitial growth).

The blood vessels and nerve in the figure are found within which type of space?

central (Haversian) canal A central (or Haversian) canal runs lengthwise at the center of each osteon.

What event at letter B leads to elongation of the bone?

chondrocyte hypertrophy and deterioration Cell division of chondrocytes occurs on the epiphysis facing side. Rather than dividing, here chondrocytes hypertrophy and deteriorate along the diaphyseal surface of the growth plate.

Bones are constantly undergoing resorption (breaking bone down) for various reasons. Which of the following cells accomplishes this process?

osteoclast

Bones do NOT have a role in __________.

waste removal Waste removal is not a role of bone; it takes place primarily in kidneys.

Cranial bones develop ________.

within fibrous membranes