Download 6. Osseous Tissue

Functions of Bone (Osseous Tissue)
• Structural Support:
• Protection:
• Storage: 1) minerals and 2) lipids
• Blood Cell Production:
• Body Movement:
• Detoxification:
(f) Sutural bone
(of skull)
(e) Sesamoid bone
(patella)
Constituents of Bone
Organic (~1/3)
Collagen
Inorganic (~2/3)
80%
Calcium
Hydroxyapatite
Ca3(PO4)2.(OH)2
15%
Calcium Carbonate
CaCO3
5%
Other Minerals:
Mg, SO4, Na, K
Specialized Bone Cells (4)
Glycosaminoglycans
(GAGs)
Flexibility!
Rigidity!
Compact Bone
Specialized Bone Cells
Hormonal Control of Bone Tissue
Human Growth Hormone (hGH):
Thyroxine:
(Pituitary gland)
(Thyroid gland)
Sex Hormones: (Ovaries and Testes)
(estrogen, progesterone, testosterone)
Calcitonin:
Calcitriol:
Inhibits Osteoclasts
(Thyroid gland)
Parathyroid Hormone:
Stimulate
Osteoblasts
(Parathyroid
gland)
(Skin and kidneys)
Stimulates Osteoclasts
Increases Ca2+ absorption
from intestine, ↓ Ca2+ in urine.
Other Health Problems Linked to Fluoridation
Increased
lead
absorption
Disrupts
synthesis of
collagen
Hyperactivity
and/or
lethargy
Muscle
disorders
Brain damage
and lowered
IQ
Arthritis
Dementia
Bone
fractures
Lowered
thyroid
function
Bone cancer
Inactivates 62
osteosarcoma enzymes
Inhibited
formation of
antibodies
Genetic
damage and
cell death
Increased
tumor and
cancer rate
Damaged
sperm and
increased
infertility
Disrupted
immune
system
So, why are we still fluoridating water?
2 Types of Ossification
1. Intramembranous Ossification
Mesoderm
Mesenchymal cells
Osteoprogenitor cells
Osteoblast
Osteocytes in bone tissue
2. ENDOCHONRAL OSSIFICATION
starts as a cartilage model of bone
Appositional Bone Growth
Bone Remodeling:
Depositing and removing bone tissue!
Fractures
Simple (Closed):
Compound (Open):
Disorders of Bone Tissue
• Osteopenia: A reduction in bone mass with age.
• Osteomalacia (‘Rickets’ in children): Defective
mineralization of bone, resulting in too much
flexibility, bone cannot bear weight sufficiently.
• Osteoma: Cancer of bone tissue (uncontrolled
bone growth, a malignant tumor = cancer).
• Osteoporosis: A significant reduction in bone
mass that impairs function.
From too little mineralization of bones for these
reasons:
1) Decrease in hormone levels.
2) Deficiency of minerals in youth, thus too little to
begin with.
3) Imbalance of osteoblasts and osteoclasts activity.