chapter 6 a/p

Classify the cells seen at the arrow in A.

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

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

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

Which of the following hormones is currently thought to decrease plasma calcium levels in pregnant women and children?

Calcitonin Yes, calcitonin is currently thought to decrease plasma calcium levels in children and pregnant women

Which hormone works directly in the intestine to increase plasma calcium levels

Calcitriol Yes, parathyroid hormone (PTH) activates Vitamin D into calcitriol in the kidney. Calcitriol then increases absorption of calcium in the intestine.

PTH promotes the formation of which hormone

Calcitriol Yes, parathyroid hormone promotes the formation of calcitriol.

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

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

Mechanical stress on weight-bearing bones plays a large part in bone remodeling. What single factor plays the largest role in maintaining adequate bone strength?

Gravity

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

Hematopoietic tissue is found in the spaces within the red bone marrow found 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).

Which of the following would NOT be a way that parathyroid hormone (PTH) could alter plasma calcium levels? (Which one of the following is FALSE?)

Increase osteoblasts on bone Correct. This answer is false. PTH would NOT increase osteoblasts. Osteoblasts store calcium on bone, thus lowering plasma calcium levels.

Which step in the figure contains compact bone

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

What type of cell is shown at A

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

What material makes up most of the structure at A

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

epiphyseal Plate is composed primilaly of what kind of tissue

The cartilage models used to form bones are composed of hyaline cartilage. This tissue persists within the epiphyseal plate at the boundary between primary and secondary ossification centers until early adulthood.

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

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

compact bone

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

Which of the following diseases would most likely be associated with a disorder at epiphyseal plate

achondroplasia This genetic disease can lead to shortening of the long bones due to premature closure of the epiphyseal plate.

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).

The structures in the figure collectively form 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.

During bone growth, which significant event occurs at the surface indicated by the letter C?

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).

Which structure is seen at the arrow

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

During bone growth, which significant event occurs at the surface indicated by the letter D?

bone resorption As the bone widens, the matrix at the endosteal surface is resorbed to maintain the proper thickness of the walls surrounding the medullary cavity.

During bone growth, which event is most significant at the surface indicated by the letter B

calcification of the cartilage matrix Calcification of the cartilage matrix leads to its deterioration and replacement by bone

Remodeling a kitchen to add additional cabinets to existing ones also means adding extra support. In a similar respect, bone remodeling alters bone structure without adversely affecting bone strength. What divalent cation is required to create additional bone matrix support

calcium

Which of the following substances is NOT a component of the osteoid material secreted by the cells indicated by the arrow in panel A?

calcium Calcium is an inorganic component of the bone matrix and is deposited from the interstitial fluids. The organic osteoid secreted by bone-forming cells is composed of proteoglycans, glycoproteins, and collagen.

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.

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.

Hypercalcemia can be caused by

hypersecretion of parathyroid hormone Parathyroid hormone functions to stimulate the activity of osteoclasts in bone tissue

Which of the following disorders is only associated with the type of bone shown in the figure?

lack of formation of certain skull bones and the clavicle (cleidocranial dysostosis) This genetic disorder of the processes of intramembranous ossification can result in these bones being deformed or even missing

What is the term for the layers of bony matrix surrounding the cell at A?

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

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

What bone-associated structures in panel C are indicated by the arrow?

trabeculae The honeycomb-like network of spongy bone is constructed of bony plates called trabeculae.

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

vascularity The compact bone at D would contain blood vessels as well as nerves in the central canals of its osteons. The spongy bone at B would be nourished by the surrounding fluids.