Bone formation and fracture healing

Question 1

Types of connective tissue

Answer 1

Embryonic tissue, Mature tissue

Question 2

3 types of mature tissue

Answer 2

Connective tissue proper- loose or dense
supporting connective tissue- cartilage and bone
liquid connective tissue- blood or lymph

Question 3

What does cartilage consist of?

Answer 3

A dense network of collagen fibres and elastic fibres; embedded in chondrotin sulphate.

Question 4

What is chondrotin sulphate?

Answer 4

A gel like component of the ground substance

Question 5

What does bone further subcategorise into?

Answer 5

Compact bone and Spongey bone

Question 6

Functions of the skeletal system and bones

Answer 6

-Support
-Protection
Assistance in movement
-Mineral Homeostasis
-Blood cell production (Hemopoiesis)
-Triglyceride storage

Question 7

Features of cartilage (5)

Answer 7

-More flexible than bone
-Tough and shock absorbs
-Avascular
-Gets nutrients via diffusion from the pericadium or synovial fluid
-Maintains pliable support for structures

Question 8

Types of bones

Answer 8

Long bone
Short bone
Flat bone
Sesamoid bone

Question 9

Long bone features and examples

Answer 9

Longer than they are wide, Unique shaped ends for articulations e.g femur, humerus

Question 10

Short bone features and examples

Answer 10

Often cube/box shaped, about as long as they are wide e.g carpal and tarsal bones

Question 11

Irregular bone features and examples

Answer 11

Often in groups and various shapes and sizes e.g vertebrae in spine and facial bones

Question 12

Flat bone features and examples

Answer 12

Often broad, thin, flat e.g scapulae, ribs, sternum

Question 13

Sesamoid bone features and examples

Answer 13

Found in tendons
Reduce friction on tendons
absorb and redistribute weight-bearing forces e.g patella

Question 14

Structure of bone

Answer 14

Diaphysis, Epiphysis, Metaphysis, Articular cartilage, Periosteum, Medullary cavity, Endosteum

Question 15

The diaphysis part of bone features

Answer 15

Is the bone’s shaft or body. It is hollow, yet thick and compact

Question 16

The epiphysis part of bone features

Answer 16

Are the proximal and distal ends of the bone.

Question 17

The metaphysis part of bone features

Answer 17

Are the regions between the diaphysis and the epiphysies.

Question 18

The articular cartilage feature of the bone

Answer 18

A thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone. Perforating fibres

Question 19

Periosteum part of bone features

Answer 19

dense, fibrous membrane covering bony surfaces and muscle
It contains the blood vessels and nerves that provide nourishment and sensation to the bone

Question 20

What does the periosteum part of bone help with?

Answer 20

helps with blood supply to bones during development, remodeling and repair

Question 21

The medullary cavity of bone features

Answer 21

Hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels

Question 22

Endosteum part of the bone features

Answer 22

Thin fibrous membrane that lines the medullary cavity.
A single layer of osteoblasts cells and a small amount of connective tissue

Question 23

What are the four types of cells present in bone tissue

Answer 23

Osteogenic cells, Osteoblasts, Osteocytes, Osteoclasts.

Question 24

Osteoprogenic cells

Answer 24

Unspecified bone stem cells, undergo cell division, resulting cells develop into osteoblasts

Question 25

Osteoblasts

Answer 25

Bone building cells
They synthesize and secrete collagen fibres

Question 26

Osteocytes

Answer 26

Are mature bone cells
Exchange nutrients and wastes with the blood

Question 27

Osteoclasts

Answer 27

Bone destroying cells
They are responsible for bone resorption (break down of extracellular matrix)
They also regulate bone calcium levels

Question 28

Types of cartilage (3)

Answer 28

Hyaline cartilage- covers articular surfaces of bones
Elastics cartilage- Provides both strength and elasticity to certain parts of the body e.g ears
Fibrocartilage- Strong, rigid, dense. Provides tough material for e.g intervertebral discs and pubic symphysis

Question 29

What does the bone’s flexibility depend on?

Answer 29

Collagen fibres

Question 30

Spongey bone structure

Answer 30

-Located in the interior of the bone
-Covered by the protective compact bone
-Composed of lamellae which are arranged in irregular thin column called trabeculae
- Trabeculae contain bone marrow - red and yellow
- Helps bones resist stress without breaking

Question 31

Compact bone structure (5)

Answer 31

-Composed of units called osteons
- Osteons consist of lamellae which have a common centre- central canal
- Between lamellae are small spaces called lacunae which contain osteoctyes
- Radiating in all directions from lacunae are canaliculi which join lacunae together
-The organization of osteons changes in response to the physical demands places on the skeleton

Question 32

What is bone homeostasis?

Answer 32

-It is where injured bone is removed and is replaced by new tissue
-It is the balance between osteoclasts and osteoblasts

Question 33

Repair process of a fractured bone (the phases)

Answer 33

Reactive phase
Reparative phase
Bone remodeling phase

Question 34

Reactive phase

Answer 34

-Blood vessels are broken
-Haematoma forms
-Blood circulation ceases
-Swelling and inflammation occur in response to dead cells, producing debris
-Phagocytes begin to remove dead or damaged tissue
-Hours to days

Question 35

Reactive -> reparative

Answer 35

Formation of soft callus which bridges broken ends of bone

Question 36

Reparative phase

Answer 36

-Nearly healthy bone tissue osteoprogenitor cells develop into osteoblasts forming spongey bone trabeculae whihc join living and dead bone together
-Fibrocartilage coverted to spongey bone and the callus is now a bony ‘hard’ callus
-Days to weeks

Question 37

Remodelling phase

Answer 37

-Dead portions of original bones are reabsorbed by osteoclasts
-Compact bone replaces spongey bone around border of fracture
-Usually a thickened surface remains as evidence of a fracture site