Bone
Development &
Growth
Intramembranous Bones
• Forms many flat skull bones, parts of the
mandible, and clavicles.
Ossification Steps:
1. 1 ossification center forms in CT
2. MesenchymalOsteoblastsOsteocytes
3. Blood vessels
4. Spongy bone
5. Compact bone
Intramembranous Bones
Endochondral Bones
• All bones except some bones of the skull and
clavicles.
• Fetal development-early adulthood
Steps
1. Hyaline cartilage cellsOsteoblasts in diaphysis
2. Primary ossification center in diaphysis develops
3. Blood vessels, fibroblastsOsteoblasts
4. Osteoblasts secrete spongy bone matrix in diaphysis
5. Secondary Ossification in epiphyses forms
6. Epiphyses ossify and remodeling to final form
Endochondrial Bones
Osteoblasts
Osteoclasts
http://youtu.be/0dV1Bwe2v6c
Growth at the Epiphyseal Plate
• Growth in width, or
thickness, occurs
through appositional
growth due to
deposition of bone
matrix by osteoblasts
beneath the periosteum.
Homeostasis of Bone Tissue
• In adult skeletons, bone remodeling is
balanced by bone deposit (osteoblasts) and
removal (osteoclasts), bone deposit occurs
at a greater rate when bone is injured, and
bone resorption allows minerals of
degraded bone matrix to move into the
blood.
*Bone resorption is the process by which
osteoclasts break down bone and release the
minerals, resulting in a transfer of calcium
from bone fluid to the blood.
Factors Affecting Bone
Development, Growth and Repair
• Vitamin A, C, and D deficiencies
• Insufficient Pituitary growth hormone
secretions (Dwarfism/Giantism)
• Thyroid hormone deficiency
• Sex hormones promote bone formation and
stimulate ossification of epiphyseal plates.
• Physical activity
Group Assignment
• Each group will be assigned 1 bone function.
Instead of reading about each bone function,
the lead group for that function will outline the
important main ideas then they will share that
information with each of the other groups.
1. Support & Protection
2. Body Movement
3. Blood Cell Formation
4. Inorganic Salt Storage