54 As a long bone develops the point where osteoblasts first

54) As a long bone develops, the point where osteoblasts first replace calcified cartilage with spongy bone becomes the ________, from which further development proceeds.

A) primary ossification center

B) metaphysis

C) periosteum

D) secondary ossification center

E) epiphyseal line

55) As cartilage enlarges in step 1 of endochondral ossification, ________ near the center of the shaft increase in size.

A) chondrocytes

B) osteocytes

C) leukocytes

D) osteoclasts

E) osteoblasts

56) The vessels supplying blood to the inner (diaphyseal) surface of each epiphyseal plate, where bone is replacing cartilage, are called ________ vessels.

A) periosteal

B) epiphyseal

C) metaphyseal

D) endochondral

E) endosteal

57) Blood vessels that supply the ends of long bones are called ________ vessels.

A) endochondral

B) metaphyseal

C) periosteal

D) epiphyseal

E) endosteal

58) An individual with otherwise normal features, but having very short limbs, may have a condition known as ________, in which epiphyseal cartilages grow unusually slowly.

A) gigantism

B) achondroplasia

C) Marfan\'s syndrome

D) osteomalacia

E) rickets

59) Differences in body size and proportions between males and females result from the different effects of ________, which affect(s) the growth of the bones.

A) calcitriol

B) vitamins A & C

C) vitamin D

D) sex hormones

E) calcium and phosphate salts

60) The simultaneous process of adding new bone and removing previously formed bone is called ________.

A) internal callus formation

B) endochondral ossification

C) osteomalacia

D) bone remodeling

E) intramembranous ossification

Solution

54) The long bone contains a shaft called diaphysis and an expanded head called epiphysis. An epiphyseal plate of hyaline cartilage separates the marrow cavities of epiphysis and diaphysis. Metaphysis is the region between epiphysis and diaphysis. During bone growth, each metaphysis contains an epiphyseal or growth plate. It is a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length. When a bone growth is completed in lengthwise, then the cartilage in the epiphyseal plate is replaced by bone. Option B is correct.

55)

The intramembranous ossification process includes four steps. First, the mesenchyme is condensed into soft sheet of tissue supplied with blood vessels. It is known as intramembranous tissue. The mesenchymal cells line up along the blood vessels and become osteoblasts. Osteoblasts are bone forming cells that form the organic matter of the matrix and involved in mineralization of the bone. Option E is correct.

56)

The vessels supplying blood to the inner (diaphyseal) surface of each epiphyseal plate, where bone is replacing cartilage, are called metaphyseal blood vessels. Option C is correct.

57)

The blood vessels supplying in the end of long bones are called epiphyseal blood vessels because the head of the bone is called epiphysis and it grows in length. Option D is correct.