December 12, 2014

Journal: What is the difference between
a ball and socket joint and a hinge joint?
Bone Growth
Ossification - formation of bone in the
body
 Bones grow longitudinally to develop
height and horizontally so they can
better support our weight

Cells Involved in Bone Growth
Osteoprogenitor cells
 Osteoblasts
 Osteocytes
 Osteoclasts

Osteoprogenitor Cells
Nonspecialized cells that can turn into
other cells as needed
 Found in the periosteum, endosteum,
and the central canal of compact bones

Osteoblasts
Actually form the bones by secreting of
calcium and other minerals that give a
bone its usual characteristics
 Developed from osteoprogenitor cells

Osteocytes
Mature bone cells
 Developed from osteoblasts

Osteoclasts

Tears down bone material and help
move calcium and minerals into the
blood
Bone Development

Endochondral Ossification: Shaped
cartilage is replaced by bone as a child
grows older
Development Before Birth
Cartilage bone forms
 Periosteum surrounds cartilage bone and the
cartilage beings to break down
 Spongy bone is created by osteoblasts

 Now called the primary ossification center

Compact bone begins to replace the spongy bone
Development After Birth
Long bones continue to grow
 Secondary ossification begins with spongy
tissue forming and not breaking down
 Epiphyseal plate (growth plate): a thin band
of cartilage forms between ossification
centers to allow for continued growth

 Hormones control bone growth
 Eventually growth plate becomes ossified and
growth stops
Natural Bone Deterioration
As the body ages the bones and
cartilage deteriorates
 Total bone mass also gradually
decreases as we age as well

Osteoporosis
Disease where bone
density decreases and
tissues deteriorate
 Causes bones to break
more easily
 Occurs in women four
times more than men

Arthritis
Inflammation of the joints
 Cartilage, tendons, and joints becomes
less flexible and decreases the range of
motion

Scoliosis

Abnormal curving of the spine which
makes it appear in a ‘c’ or ‘s’ shape
instead of a straight line
Types of Bone Fractures
Hairline Fracture
Fine, fracture
that does not
completely
break the bone
 Looks like a
piece of hair on
X-ray

Simple Fracture
Also known as a
closed fracture
 A break without a
puncture to the skin

Spiral Fracture

When the bone is severely twisted
Greenstick Fractures
Incomplete breaks
 Often occurs in
children because they
have softer bones than
adults

Comminuted
Fracture

Bone is crushed
to the point that
it becomes
fragmented or
splintered
Compound Fracture
Also known as an open fracture
 When the bone is pushed through the skin
 Deep tissues have the ability to be exposed to
bacteria and infection can occur

How a Bone Heals







Bone breaks and severs the blood vessels within the bone
Blood leaking out of these vessels clots to form a fracture hematoma
 Helps stabilize the bone and line it up for mending
Bone dies without blood and dead cells are removed
Fracture hematoma develops tougher tissue and becomes a soft callus
Fibroblasts produce collagen which strengthens the soft callus
Osteoblasts produce bone cells which form a bone callus
Osteoclasts and osteoblasts work together to replace bone callus with
harder compact bone