Chapter 6 Part 2

- 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.

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

the formation of bone in a membrane

Which step in the figure contains compact bone?

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

The stages of bone fracture healing:

(1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, (4) bone remodeling.

Old Norse stories tell of a famous Viking named Egil, who lived around 900 AD. His skull was greatly enlarged and misshapen, and the cranial bones were thickened (6 cm, more than 2 inches, thick). He had headaches from the pressure exerted by enlarged vertebrae on his spinal cord. So much blood was diverted to his bones to support their extensive remodeling that his fingers and toes always felt cold and his heart was damaged through overexertion. What bone disorder did Egil probably have? A - Paget's disease B - Osteoporosis C - Rickets D - Osteomalacia

A - Paget's disease Paget's disease is characterized by excessive and abnormal bone remodeling. It results in irregular thickening of bone tissue and often affects the skull and spine, causing pain and deformity.

What is the weakest part of a developing, adolescent long bone? A - the epiphyseal plate B - the epiphyses C - the diaphysis D - the medullary cavity

A - the epiphyseal plate The epiphyseal plate is a weak point because of the lack of calcification.

Which of the following statements is true? A - Hormones determine where remodeling occurs within the skeleton. B - After the age of 21, most people will not experience longitudinal growth of bones. C - By the age of 21, the width of the bones stops changing. D - PTH will increase calcium deposits in the bone matrix.

B - After the age of 21, most people will not experience longitudinal growth of bones. Longitudinal bone growth ends when the bone of the epiphysis and diaphysis fuses. This process, called epiphyseal plate closure, happens at about 18 years of age in females and 21 years of age in males.

Which of the following pairings is correct? A - rickets; deficiency of vitamin A B - Paget's disease; excessive and haphazard bone deposition and resorption C - osteomalacia; excessive mineralization of the bone D - osteoporosis; increased bone density

B - Paget's disease; excessive and haphazard bone deposition and resorption

What is the first stage in the healing of a bone fracture? A - bone remodeling B - formation of a hematoma C - formation of a bony callus D - formation of a fibrocartilaginous callus

B - formation of a hematoma This is the first stage in the healing of a bone fracture.

Hypercalcemia can be caused by_________. A - insufficient vitamin D levels in the body B - hypersecretion of parathyroid hormone C - reduced parafollicular cell activity D - All of the listed responses are correct.

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

What controls bone remodeling? A - hormones and diet B - mechanical stress and hormones C - mechanical stress and diet D - the nervous system and hormones

B - mechanical stress and hormones Remodeling goes on continuously in the skeleton, regulated by genetic factors and two control loops that serve different homeostatic conditions. One is a negative feedback hormonal loop that maintains Ca2+ homeostasis in the blood; the other involves responses to mechanical and gravitational forces acting on the skeleton.

Which of the following refers to a bone disorder found most often in the aged and resulting in the bones becoming porous and light? A - Paget's disease B - osteoporosis C - rickets D - osteomalacia

B - 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.

You're talking with Liliana before her release from the hospital. Which of her statements indicates the need for further patient education? A - "At last I have an excuse for taking walks outside in the sun!" B - "My parathyroids are really important for maintaining my bones!" C - "The only supplement I should need would be calcium, so I will take a calcium supplement every morning." D - "Will the doctor have my vitamin D levels tested?"

C - "The only supplement I should need would be calcium, so I will take a calcium supplement every morning." Liliana needs to know that to absorb the calcium from those supplements, she will require vitamin D.

Which of the following statements is true regarding the future actions of the vessels in the medullary cavity and the vessels in the epiphyses of the bone? A - They will grow to a certain size and then maintain all of the cartilage seen in the figure. B - They will grow and encourage bone formation until all articular cartilage is ossified. C - They will grow and encourage bone formation until the epiphyseal plate eventually ossifies. D - They will eventually degrade and die, leaving the bone with little or no blood supply.

C - They will grow and encourage bone formation until the epiphyseal plate eventually ossifies. The loss of the epiphyseal plate will seal the epiphysis and diaphysis and eventually end the lengthening of the bone.

Which of the following are correctly matched? A - linear fracture; the break is perpendicular to the bone's long axis B - nondisplaced fracture; the fractured bone ends are misaligned C - compound fracture; the fractured bone ends penetrate the skin D - incomplete fracture; the bone is broken through

C - 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 statements is true? A - Most bones in the body are formed by intramembranous ossification. B - Endochondral ossification occurs within fibrous connective tissue membranes. C - Endochondral ossification leads to the formation of the clavicles and cranial bones. D - During endochondral ossification, hyaline cartilage is broken down and replaced with bone.

D - During endochondral ossification, hyaline cartilage is broken down and replaced with bone.

When assessing Liliana's condition relative to her tibia fracture after the open reduction, the nurse will be especially alert for signs of which of these problems? A - Bleeding. B - Failure of the red bone marrow to create enough erythrocytes. C - Inadequate calcium for healing. D - Infection.

D - Infection The laceration caused by the broken end of the bone creates a breach in the protective barrier of the skin, providing an entry point for bacteria and other microorganisms.

Which hormone is NOT matched with its correct function? A - osteocalcin; helps regulate glucose metabolism B - growth hormone; lengthens long bones C - PTH; indirectly stimulates osteoclast activity D - calcitonin; increases blood calcium levels

D - calcitonin; increases blood calcium levels Calcitonin is produced in the thyroid gland; it plays a minor role in regulating Ca2+ homeostasis by decreasing blood calcium levels.

Which of the following substances is NOT a component of the osteoid material secreted by the cells indicated by the arrow in panel A? A - collagen B - glycoprotein C - proteoglycan D - calcium

D - calcium

Which of the following is UNLIKELY to affect bone remodeling? A - low blood Ca2+ concentration B - parathyroid hormone C - mechanical stress D - glucagon

D - glucagon Glucagon's main action is to increase blood glucose levels by triggering the breakdown of glycogen in the liver; it does not affect bone remodeling.

The area where blood vessels are penetrating the center of the bone used to be occupied by which tissue? A - adipose tissue B - fibrocartilage C - dense connective tissue D - hyaline cartilage

D - 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.

- Classify the cells seen at the arrow in image A.

Osteoblasts

- Which of the following diseases would most likely be associated with a disorder at A?

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

- 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.

- 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 structure indicated by the arrow is composed primarily of what tissue?

hyaline cartilage 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 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)

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

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.

- What bone-associated structure in panel C is indicated by the arrow?

trabeculae