Bone and Soft Tissue

Question 1

What types of bone are there?

Answer 1

Trabecular bone (cancellous bone, spongy bone) 
Cortical bone (compact bone = hard encasing bone) 

The trabecular bone is separated by bone marrow and fat.

Question 2

What is woven bown?

Answer 2

Bone being repaired, rapidly growing, immature bone.

Question 3

What is the intramembranous model of ossification?

Answer 3

Bone that is mineralized fibrous tissue.

Question 4

What is the endochondral model of ossification?

Answer 4

Cartilage that becomes mineralized.

Question 5

What type of bone growth characterizes long bones typically?

Answer 5

Endochondral ossification.

Question 6

What type of bone growth typically characterizes the bones of the skull?

Answer 6

Intramembranous ossification.

Question 7

What do osteoclast do? What do osteoblasts do?

Answer 7

Consume or degenerate existing bone. Lay down new bone. Both are necessary to maintain and grow and develop bone.

Question 8

Why is bone constantly remodeled?

Answer 8

Because there is a high degree of stress and pressure exerted on bone requiring near constant repair and reproduction.

Question 9

Osteosarcomas are usually found

Answer 9

In the metaphysis

Question 10

What inherited defect characterizes Achondroplasia

Is it autosomal recessive or dominant?

Answer 10

Dwarfism caused by an autosomal dominant condition whereby an inherited defect in collagen matrix proliferation at the growth plate, or physis, exists thereby preventing growth of long bones via endochondral ossification mechanisms. The head, however, remains normal sized as the bones of the skull form from a different mechanism.

Question 11

What bones are most affected in achondroplasia?

Answer 11

long bones of the peripheral skeleton derived from cartilage. Axial and craniofacial skeleton is not affected.

Question 12

What receptor is defective in achondroplasia?

Answer 12

Fibroblast growth factor receptor 3 aka FGF3

Question 13

Osteogenesis imperfecta results from a defective type of which collagen?

Answer 13

Type I collagen

Question 14

What is the hallmark symptom of osteogenesis imperfecta?

Answer 14

Brittle bones that break/fracture easily.

Question 15

What other structures are composed of type I collagen that may be affected by osteogenesis imperfecta?

Answer 15

Sclera, Middle ear ossicles ( hearing loss)

Dentin - misshapen- hereditary opalescent dentin

Question 16

Osteopetrosis is a group of disorders characterized by defect in activity of what cell?

Answer 16

Osteopetrosis is a problem of Osteoclastic activity.

Question 17

What characteristics typify osteopetrosis ?

Answer 17

Bones that appear thick, but are really actually brittle and may fracture and break very easily.

Question 18

What makes bones so brittle and weak in osteopetrosis?

Answer 18

Overactive, unopposed osteoblast activity leads to chronic laying down of bone with minimal bone resorption yielding thick ill-constructed bones.

Question 19

What other complications may result from osteopetrosis?

Answer 19

Mylephthestic disorders- bone marrow is crowded out leading to :
Anemia
Decreased WBC count (increased risk of infection)

Decrease in bone vascularity

Foramina are narrowed and the nerves exiting and entering them may be pinched.

Question 20

The bone is osteopetrosis is

Answer 20

Petrified

Question 21

What are the main stages in bone repair?

Answer 21

Hematoma and inflammation (day 1-7) 
Soft callus (2-3 weeks) 
Hard callus (2-4 months) 
Remodeling (several months - years)

Question 22

Osteonecrosis

Answer 22

avascular necrosis
aspetic necrosis

Infarction of the bone due to ischemia/anoxia leads to bone cell death early on, then bone marrow cells later in the course.

Question 23

What histological hallmark is there of osteonecrosis ?

Answer 23

Absent nuclei in osteocytes

Question 24

Osteomyelitis

Answer 24

infection of the bone

Question 25

Acute osteomyelitis

Answer 25

Fever, malaise, elevated ESR
Histologically pus is seen
Bone can be destroyed eventually

Mostly neutrophilic infiltrate

Question 26

Chronic osteomyelitis

Answer 26

unresolved acute infection- leads to dead bone = sequestrum

More lymphocytes and plasma cells infiltrate