Bone
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Bones are connected to each other to form skeleton, which forms the framework of the body. Bone tissue is formed by collagen matrix hardened by deposited calcium.
Structure[edit | edit source]
Gross anatomy[edit | edit source]
Individual bone structure[edit | edit source]
- Compact/cortical bone - makes up outer part of bone, rigid, dense, highly organised bone tissue
- Cancellous/spongy bone - makes up inner part of bone, more elastic and porous, storage of bone marrow
Cellular structure[edit | edit source]
- Osteoblasts - produce matrix (osteoid), build up bone tissue
- Osteoclasts - secretes acids and enzymes to breakdown bone tissue
- Osteocytes - maintain bone tissue by mineralising osteoid
Molecular structure[edit | edit source]
Matrix[edit | edit source]
- Inorganic
- Organic - Made up of 90-95% collagen fibres, giving bone its powerful tensile strength.
Woven or lamellar[edit | edit source]
Functions[edit | edit source]
Mechanical[edit | edit source]
- Protect internal organs
- Give shape and support to the body
- Movement
Synthetic[edit | edit source]
- Manufactures blood cells from the bone marrow (hematopoiesis)
Metabolic[edit | edit source]
- Mineral storage
- Fat storage
- Role in acid-base balance
Remodelling[edit | edit source]
Purpose[edit | edit source]
- To allow bone to ordinarily adjust strength in proportion to the degree of bone stress. When subjected to heavy loads, bones will consequently thicken.
- To rearrange shape of bone for proper support of mechanical forces in accordance with stress patterns.
- To replace old bone which may be brittle/weak in order to maintain toughness of bone. New organic matrix is needed as the old organic matrix degenerates.
Calcium homeostasis/balance must exist between osteoclasts and osteoblasts activity[edit | edit source]
- If too much new tissue is formed, the bones become abnormally large and thick (acromegaly)
- Excessive loss of calcium weakens the bones, as occurs in osteoporosis
Repair[edit | edit source]
Disorders[edit | edit source]
- Osteoporosis
- Osteoarthritis
- Osteomalacia
- Rickets
- Epiphyseal plate disorders
References[edit | edit source]
see adding references tutorial.
- ↑ Hall JE. Guyton and Hall textbook of medical physiology e-Book. Elsevier Health Sciences; 2015 May 31.