Embryonic skeleton:fashioned from fibrous membranes or cartilage to accommodate mitosis.
Radiograoh of an 18-week old fetus, showing intramembranous ossification occurs at centers of ossification in the flat bones of the skull. Endochondral ossification has formed bones in the diaphysis of long bones. The epiphyses are still cartilage at this stage of development.
Of all the minerals in the body, there is more calcium than any other. It makes up somewhere around 2% of our total adult body weight, stored mostly in our bones and teeth. Bone is made up of a crystalline mineral compound embedded within a living protein matrix. This crystalline mineral compound, called hydroxyapatite, is formed principally from calcium and phosphorus. It is essential for healthy bone development and bone maintenance, and gives our bones both strength and rigidity.
Vitamin A is available in liver, eggs, butter, green leafy vegetables and carrots. The animal source supplements (retinols) may cause toxicity but plant sources (B carotene) do not. Daily intake of retinols should be less than 10,000 IU.
In the absence of this vitamin, calcium is poorly absorbed, the bone matrix is deficient in calcium, and the bones are likely to be deformed or very weak.Vitamin D is also essential for bone health. We get most of our vitamin D from the action of sunlight on our skin but it is also found in oily fish, fish oils such as cod liver oil, meat (particularly liver), eggs and dairy products.Our bodies contain a precursor of vitamin D which is converted into active vitamin D when we are exposed to sunlight.Vitamin D increases the absorption of calcium from foods, which helps to provide more calcium for building bones.
Bone Growth & Development by Kerstin Karen Vicente, RN
Osteocyte – mature bone cell, enclosed in
Osteoblast – bone-forming cell; secretes
collagen fibers and calcium salts of bone
Osteoclast – bone-destroying cell; breaks
down ECM to release calcium into the
O S T EB B LA
O S T E O C LA
Consists of a
of bone wit
A bonding of
multiple fibers and
chemicals of different
fibers and crystallin
The crystalline salts deposited in the matrix
of bone are composed principally
of calcium and phosphate, which are
combined to form hydroxyapatite crystals.
Calcium (Ca), phosphate (PO4), and hydroxide
Bone develops from
Bone develops from
Forms bones of skull and Forms all bones below
clavicle (all flat bones)
base of skull
Begins at 8 weeks of
Begins 2nd month of
Makes up 2% of body weight
99% Stored in bones
A narrow range of 9-11 mg Ca/100 ml
blood maintained at all times.
Bone remodeling - key in maintaining
proper blood calcium levels
1% Constant supply of Ca2+ in the blood
stream needed for:
◦Transmission of nerve impulses
A major mineral in the body's bone crystal,
phosphorus is found in dairy products and
Primarily found in bone crystals,
magnesium improves bone strength.
Older adults are more likely to be deficient
Calcium supplements that contain
magnesium can help.
Necessary for bone formation and
mineralization, blood clotting, and may
assist in channelling calcium directly to the
bone rather than the blood vessels.
Collagen is the main protein in bone, and
Vitamin C is necessary for collagen
Vitamin C is present in citrus fruits and
tomatoes and in many vegetables.
Necessary for cells to differentiate
normally and for normal skeletal growth,
and also is extremely important for eye
Too little vitamin A is a major cause of
Too much vitamin A can cause bone loss
and increase the risk of hip fracture.
Vitamin D is necessary for the proper
absorption of calcium in the small intestine.
Growth Hormone (Somatotropin)
From: Pituitary gland Other fx
stimulates bone and
Stimulates activity in muscle growth
the epiphyseal platesmaintains the normal rate of
protein synthesis in all body
Main regulator of
speeds the release of fats
as an energy source for