ossification

Question 1

What is ossification?

Answer 1

A process of laying down bone to a primary ossification centre in cartilage intrauterine

Question 2

What is secondary ossification?

Answer 2

Secondary ossification centre target the areas primary centre hasn’t reached

Question 3

Where is the primary centre in a long bone?

Answer 3

In a long bone the primary centre is in the diaphysis shaft in middle

Question 4

Where is the secondary ossification centre?

Answer 4

The secondary center is in the epiphysis- top and bottom of bone Be careful of the epiphyseal growth plate

Question 5

What’s osteoporosis?

Answer 5

Osteoporosis- bone loss is at a rate above the norm, accelerated loss of bone mineral density leading to fragile skeleton low bone density score increased risk of bone fracture

Question 6

Who does osteoporosis mainly affect?

Answer 6

Traditionally post menopause Can affect all ages due to lifestyle choices, illness, medications ect

Question 7

What type of training helps prevent?

Answer 7

Strength training needed to provide localised changes adding tensile load to proximal end laying down more bony tissue

Question 8

Osteoporosis T score

Answer 8

T <-2.5= osteoporosis

Question 9

Osteopenia T score

Answer 9

T<-1.5=osteopenia

Question 10

Normal T score

Answer 10

T=1.0

Question 11

When do primary ossification centres appear?

Answer 11

Majority of primary centres appear between the seventh and twelfth week of intrauterine (in the uterus) life virtually all are present before birth

Question 12

When do secondary ossification centres appear?

Answer 12

Appear after birth in parts of the cartilage model that ossification from the primary centre has not spread

Question 13

The bone formed by secondary centres are?

Answer 13

almost entirely cancellous

Question 14

What is a epiphyseal growth plate?

Answer 14

The plate of cartilage between these metaphysics and epiphysis regions

In growing bones, each metaphysis contains an epiphyseal growth plate- a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length.

Question 15

What happens when the growth plate disappears?

Answer 15

When the bone ceases to grow in length at around ages 12-24 the cartilage is replaced by bone, resulting in a bony structure called the epiphyseal line.

When the growth plate disappears the diaphysis and epiphysis fuse

Question 16

what does the Endosteum & periosteum produce?

Answer 16

Production of osteoprogenitor cells and osteoclasts

Question 17

what does an osteoclast do? 3

Answer 17

Remove bone during growth and remodeling (‘osteoClasts ->Cut bone’)

- Osteoclasts help regulate blood calcium levels 

- They are also target cells for drug therapy used to treat osteoporosis

Question 18

where is an osteoclast located?

Answer 18

Howship’s lacunae

Question 19

what do osteoclasts release?

Answer 19

cathepsin K and collagenase

Question 20

what does an osteoblast do?

Answer 20

Facilitate the mineralization of osteoid matrix (‘osteoBlasts ->Build bone’) and are interconnected via dendritic extensions

Question 21

what are osteocytes? what do they contain?

Answer 21

Mature bone cells, are the main cells in bone tissue and maintain its daily metabolism, such as the exchange of nutrients and wastes with the blood. Like osteoblasts, osteocytes do not undergo cell division.

Differentiated osteoblasts trapped in the bone matrix

containing cytoplasmic projections with osteoblasts and osteocytes

Question 22

what cells are found in bones? 4

Answer 22

osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts.

Question 23

Osteoprogenitor cells 3

Answer 23

unspecialised bone stem cell.

The only bone cells to undergo cell division, the resulting cells develop into osteoblasts,

found along the inner portion of the periosteum, in the endosteum and in the canals within bone that contain blood vessels.

Question 24

diaphysis

Answer 24

the bones shaft/body long cylindrical main portion

Question 25

epiphysis

Answer 25

proximal and distal ends of bone

Question 26

metaphysis

Answer 26

the regions between the diaphysis and epiphysis

Question 26

articular cartilage, what is it? what does it do? what does it lack?

Answer 26

a thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation (joint) with another bone.

Articular cartilage reduces friction and absorbs shock at freely moveable joints.

Because the articular cartilage lacks a perichondrium and blood vessels, repair of damage is limited.

Question 27

medulla cavity
what is it?
What does it contain?
what is it designed for?

Answer 27

a hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults. This cavity minimises the weight of the bone by reducing the dense bony material where it is least needed. The long bones tubular design provides maximum strength with minimum weight.

Question 28

Endosteum

Answer 28

a thin membrane that lines the medullar cavity. It contains a single layer of bone forming cells and a small amount of connective tissue.