Bones

Question 1

Describe the formation of woven bone

Answer 1

The process takes 2-4 weeks, depends entirely on the cells in the local periosteum: depends on severity, the position of the fracture and age of the patient .

Question 2

What do inflammation and additional blood flow lead to

Answer 2

callus formation: this is essentially a scab for your bones. Osteoblasts quickly form woven bone to bridge the gap however this is weak as the collagen fibres are irregular.
Lamellar bone is then laid down, the collagen is organised in regular sheets which gives strength and resilience. then remodelling by osteoclasts restore bone to the original shape

Question 3

What leads to an increase in bone density

Answer 3

the excessive mechanical stimulation

Question 4

What is wolf law

Answer 4

Bone adapts to the load under which it is placed

Question 5

What leads to a decrease in bone density

Answer 5

Non-weight bearing if you’re immobilised in bed etc.
sex-hormone deficiency such as menopause
Endocrine/nutritional disorder

Question 6

Describe the formation of the cartilage (think Cartilage so Chondro) model

Answer 6

This is formed by chondroblasts and are reshaped by chondrocytes. The cartilage is replaced by bone through the process of ossification which begins in the epiphysis and epiphyseal plate (post-birth endocondrial ossification) before birth its in the diaphysis

Question 7

What is the main limiting factor in achieving peak bone mass

Answer 7

Age 30-40 peak then bone loss after

Question 8

What are the four main parts of the long bone structure

Answer 8

Epiphysis = the flared end of the bone head
Diaphysis = the long bit of the bone, with bone marrow in the marrow cavity where RBC formation is
Metaphysis = region of growth during childhood
Periosteum = made of fibroblast which form collagen
Mesenchymal cells which differentiate to form chondroblasts and osteoblasts
and osteoclasts

Question 9

What is the composition of the bone matrix

Answer 9

Water
collagen
hydroxyapatite

Question 10

Diseases associated with the bone matrix

Answer 10

rickets = lack of vitamin D, Ca2+ is not absorbed
scurvy = vitamin C deficiency lack of collagen

Question 11

osteocytes

Answer 11

These are entombed osteoblasts which maintain the bone matrix through cell to cell communication via projections known as canliculi and influence bone remodelling

Question 12

What controls the equilibrium that exists between osteoblasts and osteoclasts

Answer 12

Calcitonin = decreases the activity of osteoclasts and therefore decreases level of Ca2+ in the blood
and PTH = which increases the levels of ca2+ in the blood thus increasing the levels of osteoclasts