Bone Growth and Development Part 2 Flashcards
1
Q
- What does PTH do
A
increases blood calcium levels and regulates phosphate
2
Q
- How does PTH increase blood calcium levels and regulate phosphate
A
- By releasing calcium from bone
- By stimulating vitamin D
- By conserving calcium in the kidney while reducing reabsorption of phosphate
3
Q
- What 2 things does vitamin D stimulated by PTH do
A
- Enhances absorption of calcium in the gut
- Increases calcium and phosphate reabsorption from bone by increasing Osteoclast activity and decreasing Osteoblast activity
4
Q
- What gland releases calcintonin
A
Thyroid gland
5
Q
What is another name for calcintonin
A
Thyroid C cells
6
Q
- What does calcintonin (thyroid C cells) do
A
decreases blood calcium levels
7
Q
- How does calcintonin decreases blood calcium levels
A
Decreases blood calcium levels by:
- By inhibiting osteoclast activity
- By reducing calcium reabsorption in the kidney
8
Q
- Explain the process of bone fracture and repair
A
- Periosteum is breached. haematoma occurs
- Haematoma clot tissue is replaced by vascular collagenous tissue called granulation tissue
- New osteoprogenitor cells arise from mesenchymal cells and neutrophils, Macrophages phagocytose the heamatoma and necrotic debris
- Production of 2 types of calluses.
calluses are very established by 3rd week after fracture
- Osteoclasts remove woven bone and osteoblasts replace this with lamellar bone. Remodelling of callus takes many months.
- Full replacement with lamellar bone occurs
Some residual fibrosis, irregular cortical bone and muscle scarring lingers
9
Q
what are the 2 types of calluses produced in bone fractures
A
- External callus
- Internal callus
10
Q
what is an external callus
A
osteoblast bridges fracture on the outside, using cartilage
11
Q
what is an internal callus
A
osetoblast bridges fracture in the cavity using woven bone
12
Q
what is the orientation of trabecular bone dependant on
A
determined by stresses applied when mobile
