MMB (048) Practical of Normal and Abnormal Bone Growth

Question 1

What do we call the process of laying down new bone material by osteoblasts?

Answer 1

Ossification

Question 2

Which of the following types of bone develops out of a non-cartilage connective tissue scaffold?

A. Intramembranous

B. Endochondral

Answer 2

A. Intramembranous

Question 3

Answer 3

Question 4

Answer 4

Question 5

Answer 5

Question 6

Answer 6

Question 7

1) Achondroplasia can cause which of the following:

A. Gigantism

B. Dwarfism

Answer 7

B. Dwarfism

Question 8

2) Achondroplasia is a hereditary disorder with which of the following symptoms?

A. Short stature

B. Large head with prominent forehead

C. Spinal kyphosis or lordosis

D. Shortening of proximal limbs

E. All of the above

Answer 8

E. All of the above

Question 9

3) Most cases are caused by a mutation in …….. gene

Answer 9

FGFR3 gene

Question 10

4) what is the most likely mode of inheritance of achrondoplasia?

A. Autosomal dominant

B. Autosomal recessive

C. Xlinked

D. Incomplete penetrance

E. Multivariant inheritance

Answer 10

A. Autosomal dominant

Question 11

5) A person with achondroplasia has what chance of passing it along to his/her child?

A. 25%

B. 50%

C. 66%

D. 75%

E. 100%

Answer 11

B. 50%

Question 12

Answer 12

Question 13

Which of the following processes are disturbed in achondroplasia?

A. endochondral ossification

B. intramembranous

C. peripheral ossification

Answer 13

A. Endochondral ossification

Question 14

• The FGFR3 mutation in achondroplasia impairs cartilage proliferation at the growth plate. Which of the following explains why affected individuals have normal sized head and vertebrae but shortened limbs?”

A. Growth hormone and insulin like growth factor 1 levels only affect long bones

B. Intramembranous bone formation (flat bones) vs endochondral bone formation (long bones)

C. Flat bones are less susceptible to fracture

D.Difference in bone density

Answer 14

B. Intramembranous bone formation (flat bones) vs endochondral bone formation (long bones)

Question 15

Answer 15

Question 16

Which of the following conditions is characterized by brittle bones and predisposition to fractures?

A. Pituitary dwarfism

B. Achondroplastic dwarfism

C. Acromegaly

D. Osteogenesis imperfecta

Answer 16

D. Osteogenesis imperfecta

Question 17

What is the genetic defect in osteogenesis imperfecta and mode of inheritance?

Answer 17

•Defects in type I collagen synthesis: mutations in genes that code for the α1 and α2 chains

•Autosomal dominant (more common)

•Autosomal recessive (severe lethal forms)

Question 18

• Which is lethal osteogenesis imperfecta?

A. Type I

B. Type II

Answer 18

B. Type II

Question 19

Answer 19

Question 20

A 2 year old boy has a history of recurrent long bone fractures. On examination, he has blue sclerae, loose joints, abnormal teeth and poor hearing. Which of the following protein, encoded by the mutated gene is responsible?

A. Collagen

B. Dystrophin

C. Fibrillin

D. Fibroblast growth factor receptor

Answer 20

A. Collagen

Question 21

Answer 21

Question 22

Answer 22

Question 23

• Which of the following disorders is characterised by growth hormone deficiency leading to affected individuals having a short stature?

A. Pituitary dwarfism

B. Achondroplastic dwarfism

C. Acromegaly

D. Osteogenesis imperfecta

Answer 23

A. Pituitary dwarfism

Question 24

Which of the following diseases is characterised by high levels of growth hormone leading to excess growth of body tissues?

A. Pituitary dwarfism

B. Achondroplastic dwarfism

C. Acromegaly

D. Osteogenesis imperfecta

Answer 24

C. Acromegaly

Question 25

Acromegaly is a syndrome that results when the anterior pituitary gland produces excess growth hormone A. Before puberty B. After puberty

Answer 25

B. After puberty (after epiphyseal fusion)

Question 26

• Gigantism is a syndrome that results when the anterior pituitary gland produces excess growth hormone A. Before puberty B. After puberty

Answer 26

A. Before puberty (before epiphyseal fusion)

Question 27

Normal formation of bone is known as osteogenesis. Another term for bone formation is A. Osteoporosis B. Ossification C. Osteosarcoma D. Osteocyte

Answer 27

B. Ossification

Question 28

Endochondral ossification begins at what age? A. During fetal development B. Birth C. Puberty D. Adulthood

Answer 28

A. During fetal development

Question 29

• Endochondral ossification ends at what age? A. Birth B. Puberty C. Adulthood D. About age 50

Answer 29

C. Adulthood

Question 30

The epiphyseal plate is the zone of A. New growth for endochondral ossification B. Growth in intramembranous bone C. Growth in the skull bones only D. Growth in the leg bones only

Answer 30

A. New growth for endochondral ossification

Question 31

• The epiphyseal plate is divided into 4 zones. The region where the bone grows longer is the zone of A. Resting cartilage B. Proliferation C. Hypertrophy D. Calcification

Answer 31

D. Calcification

Question 32

• The epiphyseal plate is divided into 4 zones. The region where chondrocytes mature and enlarge is the zone of A. Resting cartilage B. Proliferation C. Hypertrophy D. Calcification

Answer 32

C. Hypertrophy

Question 33

Intramembranous ossification results in the formation of bones that belong to which class of bones? A. Skull and ribs B. Ribs, clavicles, and spine C. Flat bones of the clavicle and skull D. Spine, skull, ribs, and scapulas

Answer 33

C. Flat bones of the skull and clavicle

Question 34

• The process of intramembranous ossification begins when? A. During embryonic development B. At birth C. In the teenage years D. Around the time of full development

Answer 34

A. During embryonic development

Question 35

The type of cells that brings about intramembranous ossification are A. Osteocyte B. Osteoblasts C. Osteoclasts D. Osteon

Answer 35

B. Osteoblasts

Question 36

Growth in the length of a long bone stops when A. The articular cartilage becomes completely ossified. B. The epiphyseal plate becomes completely ossified. C. Appositional growth at the periosteum stops. D. Intramembranous ossification is complete.

Answer 36

B. The epiphyseal plate becomes completely ossified.

Question 37

Answer 37

Question 38

• In endochondral ossification, the perichondrium that surrounded the hyaline cartilage becomes A. Circumferential lamellae B. Osteons C. Lacunae D. Perforating canals E. Periosteum

Answer 38

E. periosteum.

Question 39

Secondary ossification centers A. Are located in the diaphysis of the bone B. Are located in the epiphysis of the bone C. Are located in the fontanels D. Appear during early fetal development E. Are locations for intramembranous ossification

Answer 39

B. Are located in the epiphysis of the bone

Question 40

• Endochondral ossification A. Occurs primarily in the bones of the skull B. Involves calcification of the cartilage matrix C. Produces bone in connective tissue membranes D. Occurs when chondrocytes replace osteoblasts in the matrix

Answer 40

B. Involves calcification of the cartilage matrix

Question 41

Which of these bones is produced at least partly by intramembranous ossification? A. Clavicle B. Frontal C. Mandible D. Parietal E. All of the above

Answer 41

E. All of the above

Question 42

• In a long bone, the epiphyseal plate is A. Located in the center of the diaphysis B. The outer membrane layer on the diaphysis C. The location where growth occurs D. Produced when the epiphyseal line changes to bone E. The location for fat storage

Answer 42

C. The location where growth occurs