✅Bone Tissue

Question 1

What are the 5 functions of the skeletal system?

Answer 1

• Support
• Storage of minerals and lipids
• Blood cell production (Haemopoiesis)
• Protection
• Leverage

Question 2

What is the percentage of calcium composition in bone?

Answer 2

39%

Question 3

What is bone?

Answer 3

Bone is a connective tissue

Question 4

What are the 5 stages of bone formation?

Answer 4

1. Development of Cartilage model
2. Growth of Cartilage
3. Development of primary ossification centre
4. Development of primary ossification centre in Epiphysis
5. formation of articular Cartilage and epiphysis plate

Question 5

What are the 3 key points of bone growth?

Answer 5

Lengthening of bones at epiphyseal plate
– Grows from cartilage
• Forms epiphyseal line when growing is complete
• Undergoing constant remodeling
– Adaptation to stress
– Healing

Question 6

What are the two types of bone?

Answer 6

Dense or Compact or Cortical bone (85%)

Spongy or Cancellous or Trabecular bone (15%)

Question 7

What are Spongy or Cancellous or Trabecular bone made of?

Answer 7

Traberculae

Question 8

What are Dense or Compact or Cortical bone made of?

Answer 8

– Osteon (Haversian System)
– Central (Haversian) canal
– Lamellae
– Lacunae with osteocytes
– Canaliculi

Question 9

Describe the outer layer of The periosteum

Answer 9

dense, irregular network of nerves and blood vessels

Question 10

Describe the inner layer of the periosteum

Answer 10

– Osteoblasts
– Anchored to bone by collagen fibres that penetrate into bone

Question 11

What are the three routes that blood uses to reach the bone tissue?

Answer 11

Haversian Canals
Volkmann’s Canals
Primary blood vessels

Question 12

What are haversian canals?

Answer 12

Minute channels that lie parallel to axis of bone

Question 13

What do volkmann’s canals do?

Answer 13

Connect the Haversian canals

Question 14

What does the body have 1-2kg of (99% in bone)?

Answer 14

Calcium

Question 15

Where do calcium ions play and important role?

Answer 15

Physiological process

Question 16

What happens if calcium concentration increases by 30%?

Answer 16

Neurons and muscle cells become unresponsive

Question 17

What happens if calcium concentration decreases by 35%

Answer 17

Convulsions

Question 18

What happens if calcium concentration is reduced by 50%?

Answer 18

Death

Question 19

What are the two types of calcium homeostasis?

Answer 19

Parathyroid Hormone (PTH)
Calcitonin

Question 20

When is PTH released into the body?

Answer 20

When calcium ion in blood drops

Question 21

What 3 things does PTH do when released into the body?

Answer 21

• Stimulates osteoclast activity and enhancing of mineral recycling by osteocytes
• Increasing the rate of intestinal absorption of calcium ions by enhancing the action of calcitriol
• Decreasing the rate of excretion of calcium ions at the kidneys

Question 22

What does calcitonin do when released into the body?

Answer 22

• Inhibits osteoclast activity
• Increase the rate of excretion of calcium ions at the kidneys

Question 23

What are the 8 types of bone disorders?

Answer 23

Nutritional 
Genetic 
Cancer 
Endocrine 
Ageing 
Trauma 
Infection 
Neuromuscular

Question 24

What happens to X-rays as they pass through the body?

Answer 24

they are partially absorbed; the denser the tissue, the greater the fraction of radiation that is absorbed

Question 25

What is attenuation?

Answer 25

the reduction in intensity due to absorption and scattering.

Question 26

What does the degree of attenuation depend on?

Answer 26

the tissue’s local density & composition (bones attenuate strongly, fat attenuates much less).

Question 27

What does each tissue type have?

Answer 27

Characteristic radiodensity

Question 28

What is Dual-energy X-ray Absorptiometry (DXA) the clinical system for?

Answer 28

diagnosing osteopenia/osteoporosis

Question 29

What can DXA do?

Answer 29

Can measure body composition

Question 30

What are the 4 key points of osteopenia?

Answer 30

• Inadequate ossification • Prevalence & severity typically increase with age • Typically starts between 30-40 years of age • Epiphyses, vertebrae, jaws are most affected

Question 31

What are the 4 key points of osteoporosis?

Answer 31

• Reduction in bone mass sufficient to compromise bone function • Hormonal effects, over age 45→ 29% women & 18% men • Effects of (in)activity • Typically lead to fracture → independence loss → immobility

Question 32

What are the 2 types of fractures?

Answer 32

• Closed / simple • Open / compound

Question 33

What forms rather than lamellar bone in the initial phases of fracture healing?

Answer 33

Formation of callus of woven (rather than lamellar) bone in the initial phases of fracture healing.

Question 34

What are the 4 steps of fracture healing?

Answer 34

• Step 1 – Fracture Haematoma • Step 2 – Callus Formation • Step 3 – Ossification • Step 4 – Remodelling

Question 35

What happens at step one of the fracture healing process?

Answer 35

Immediately after the fracture, extensive bleeding occurs. Over a period of several hours, a large blood clot, or fracture hepatoma, develops.

Question 36

What happens at stage 2 of the fracture healing process?

Answer 36

An internal callus forms as a network of spongy bone unites the inner surfaces, and an external callus of Cartilage and bone stabilises the outer edges.

Question 37

What happens at step 3 of the fracture healing process?

Answer 37

The cartilage of the external callus has been replaced by bone, and struts of spongy bone now unite the broken ends. Fragments of dead bone and the areas of bone closest to the break have been removed and replaced.

Question 38

What happens at step 4 of the fracture healing process?

Answer 38

A swelling initially marks the location of the fracture. Over time, this region will be remodelled, and little evidence of the fracture will remain.