Bone

Question 1

What is rickets due to

Answer 1

Vit D defitiency

–> vit d is used to absorb calcium and phosphate

Question 2

5 bone functions

Answer 2

1. support
2. protection
3. levers
4. Resevior (for minerals)
5. Hemopoietic ( marrow cavity of bone houses bone marrow)

Question 3

What are the 4 things bone are made of

Answer 3

1. water
2. inorganic component (calcium)
3. Organic component (type 1 collagen)
4. Cells (Osteprogenitor cells, osteoblasts, osteocytes, osteoclasts)

Question 4

In which way is bone the strongest

Answer 4

bone is stronger against compression than tension

Question 5

Osteoprogenitor cells function

Answer 5

Move into blood vessels where bones need to be built then transforms into osteoblasts.
-Starts to then lay fibres around itsself (calcium + phosphates) encapsulting itself and becomeing an osteocyte

Question 6

What % of osteoblasts differentiate into osteocytes

Answer 6

10-20%

Question 7

How do osteoclasts work

Answer 7

Sit in howship lacunae and secretes acitity to start degrading the bone

Question 8

Intramembranous bone formation (+ what type of bone is it associated with)

Answer 8

• Associated with flat bones

- Mesenchyme cells form clusters (bone blastema) and differentiate into osteoblasts that deposits bone tissue

Question 9

Endochondral Ossification (+ what type of bone is it associated w)

Answer 9

-Associated w long bones, starts w cartilage

• bone starts in the center of the shaft
• capillaries and osteoblasts migrate into the epiphysis creating a secondary ossification center

Question 10

4 zones of endochondral bone formation

Answer 10

Resting zone

Proliferating zone- Chrondrocytes are stacked in prominent rows

Hypertrophy zone- deposition of minerals in matrix cause cell death which create a cavity got other cells to come

Calcification zone- After macrophages come, they create holes, calcification occurs and new bone is deposited

Question 11

Two types of bone healing

Answer 11

Primary- Gap healing and Contact healing

Secondary healing- Through the development of fracture callus (uses a cast but allows more movability)

Question 12

Contact bone healing

Answer 12

-Occurs in the cortex underlying the plate by direct haversian remodeling

• -osteoclasts start drilling holes along bone break
• -in the cylinders new osteons are built

Question 13

4 stages of gap healing

Answer 13

1. hematoma is formed, inflamation of area. cellular proliferation with 24h and eventually confined to fracture area
2. Formation of primary soft callus(few months after), smaller amount of movement= smaller calus
3. woven bone is gradually replaced by lamellar bone and the fracture is united by this bony secondary callus
4. Final phase is remodeling which may take several years