Bone (L4)

Question 1

Which bone cells secrete the organic component of the ECM?

Answer 1

Osteoblasts

Question 2

Which bone cells are found in the CT lining bone tissue?

Answer 2

Osteogenic cells

Question 3

Name the CT that lines the bone tissue externally

Answer 3

Periosteum

Question 4

What is the origin of osteoblasts

Answer 4

Osteoprogenitor cells

Question 5

What are the organic components of bone matrix?

Answer 5

Collagen type I
Proteoglycans
Glycoproteins such as osteonectin

Question 6

Identify the cell:

• Simple, Cubiodal
• Polarized
• Abundant rER, free ribosomes and Golgi bodies
• Form gap and adherent junctions

Answer 6

Osteoblasts

Question 7

What is the origin of bone lining cells?

Answer 7

Osteoblasts

Question 8

What is the origin of osteocytes?

Answer 8

Osteoblasts

Question 9

Which of the bone cells is responsible for deposition of inorganic matrix?

Answer 9

Osteoblasts

Question 10

What is the fate of most osteoblasts?

Answer 10

Apoptosis

Question 11

Which of the bone cells is responsible for secreting the osteoid?

Answer 11

Osteoblasts

Question 12

What is the name of the collagen-rich material secreted by osteoblasts?

Answer 12

Osteoid

Question 13

What is the name of the vitamin K dependent polypeptide secreted by osteoblasts?

Answer 13

Osteocalcin

Question 14

Name the polypeptide that concentrates Calcium in the bone matrix

Answer 14

Osteocalcin

Question 15

Which of the bone cells is responsible for secreting alkaline phosphatase vesicles?

Answer 15

Osteoblasts

Question 16

What is the function of alkaline phophatase?

Answer 16

Increases the local concentration of PO43-

Question 17

Hydroxyapatite crystals are formed around ____________

Answer 17

Alkaline phosphatase vesicles

Question 18

After the formation of hydroxyapatite crystals, what is required to complete the calcification of the bone?

Answer 18

Deposition of more minerals, collagen and proteoglycans

Question 19

Which of the bone cells is most abundant?

Answer 19

Osteocytes

Question 20

Which of the bone cells are entrapped in the bone matrix?

Answer 20

Osteocytes

Question 21

Which of the bone cells are found in howship lacunae?

Answer 21

Osteoclasts

Question 22

Identify the cell:

• Almond shaped
• Inactive nucleus with condensed chromatin
• Little rER, ribosomes and small Golgi body
• Long dendritic processes running in canaliculi

Answer 22

Osteocytes

Question 23

What is the mechanostat of bone formed of?

Answer 23

Osteocytes and their long dendritic processes running in canaliculi forming gap junctions with neighbouring cells

Question 24

What is the function of the mechanostat?

Answer 24

Maintain bone matrix and adjust ion levels accordingly

Question 25

What is the effect of lack of exercise on bone?

Answer 25

Wearing of the mechnostat leading to decreased bone density

Question 26

Rapid bone resorption occurs after the death of which bone cells?

Answer 26

Osteocytes

Question 27

Which cells serve as detectors for the activity of osteoblasts and osteoclasts?

Answer 27

Osteocytes

Question 28

Diffusion of metabolites from blood vessels occurs through the processes of which bone cells?

Answer 28

Osteocytes

Question 29

Which bone cells express proteins to control bone remodelling?

Answer 29

Osteocytes

Question 30

What is the origin of osteoclasts?

Answer 30

Monocytes

Question 31

Identify the cell: * Large * Multinucleated * Motile * Abundant lysosomes * Ruffled border

Answer 31

Osteoclasts

Question 32

Which of the bone cells functions in bone resorption?

Answer 32

Osteoclasts

Question 33

Sharpey’s fibers are found in the A/ Periosteum B/ Endosteum

Answer 33

Periosteum

Question 34

Which of the following bone CT is formed of 2 layers: outer fibrous and inner cellular? A/ Periosteum B/ Endosteum

Answer 34

Periosteum

Question 35

Which of the following bone CT lines the bone marrow and trabeculae A/ Periosteum B/ Endosteum

Answer 35

Endosteum

Question 36

What is the function of Sharpey’s fibers?

Answer 36

Binding periosteum to bone

Question 37

The inner periosteum contains:

Answer 37

Osteoblasts Osteoprogenitor cells Bone lining cells

Question 38

Which of the bone cells is involved bone growth and repair?

Answer 38

Osteoprogenitor cells

Question 39

The inorganic components of bone are

Answer 39

* Calcium hydroxyapatite * Non-crystalline Calcium Phosphate * Sodium * Magnesium * Postassium * Citrate * Bicarbonate

Question 40

What are the 4 types of lamellae in lamellar bone?

Answer 40

* Concentric lamellae around the Haversian canal * Interstitial, irregular lamellae between osteons * External circumferential lamellae beneath the periosteum * Internal circumferential lamellae lining the bone marrow cavity

Question 41

What are lamellae?

Answer 41

Parallel sheets of collagen type 1

Question 42

What is the structure found at the centre of a Haversian system?

Answer 42

Haversian, central canal

Question 43

What would you find between the successive layers of concentric lamellae?

Answer 43

Osteocyte lacunae

Question 44

What is the cement line?

Answer 44

Outer boundary of an osteon containing collagen, other non-collagensous protein and minerals

Question 45

Name the canals that communicate Haversian canals

Answer 45

Volkmann’s transverse perforating canals

Question 46

Identify the tissue * Non-lamellar bone * Low mineral content * High number of osteocytes * Random arrangement of collagen type I fibers

Answer 46

Woven bone

Question 47

State the location of woven bone

Answer 47

Embryo Calvaria Insertion of tendons Callus (bone repair site)

Question 48

Temporary bone is * Lamellar * Woven

Answer 48

Woven

Question 49

How does bone remodelling occur?

Answer 49

Osteoclasts break down bone | Osteoblasts form new bone and deposit minerals in it

Question 50

What happens when osteoclasts are overstimulated?

Answer 50

* Lose their mobility * Increase resorptive activity So they bore into one area of the bone Instead of sweeping a large area

Question 51

Name the hormone that stimulates osteoclasts

Answer 51

Parathyroid (Parathormone)

Question 52

Name the hormone that inhibits osteoclasts

Answer 52

Osteocalcin

Question 53

A patient arrives at the Emergency department after suffering a sudden fracture in his leg. He complains of severe pain. After many tests and a biopsy, the doctors determine that he suffers from osteosarcoma. This type of tumour originates in which bones cells?

Answer 53

Osteoprogenitor cells or osteoblasts

Question 54

Osteoporosis is common in which patients?

Answer 54

Immobilised patients Post menopausal women Old people

Question 55

What is the cause of osteoporosis?

Answer 55

Imbalance in bone turnover causing reduced bone mineral density

Question 56

A genetic mutation that leads to defective collagen type I and brittle bones is a characteristic of which disease?

Answer 56

Osteogenesis imperfecta

Question 57

Calcium or vitamin D deficiency in children causes which disease?

Answer 57

Rickets

Question 58

Which vitamin is important for calcium absorption in the stomach?

Answer 58

Vitamin D

Question 59

Epiphyseal plate distortion and bone deformities in children due to weight are characteristics of which bone disease?

Answer 59

Rickets

Question 60

Calcium or vitamin D deficiency in adults causes which bone disease?

Answer 60

Osteomalacia

Question 61

Deficiency in calcium in adult bones causes

Answer 61

Decalcification of existing bone | Deficient calcification of new bone

Question 62

Softening of bones in adults is a characteristic feature of which bone disease?

Answer 62

Oseteomalacia

Question 63

What are the effects of Softening of bones in osteomalacia?

Answer 63

Increased tendency of both major and minor fractures causing pain