bone - university of · pdf filemicroscopic anatomy of compact bone •canaliculi...
TRANSCRIPT
Main points in this lecture
• To identify the Specialized form of connective tissue and describe their functions.
• Different bone cells must be known .
• To Differentiate the types of bone .
• Nice to know some term of changes in bone , and must remember at least 2 of them .
• Bones are :
• Specialized form of connective tissue:
• mineralized collagen matrix, therefore very
• rigid and strong while still retaining some
• degree of flexibility
Function of Bones
1. Protection- of soft tissues and organs. 2. Movement – muscles attached to bones
,contraction causes movement.
3. Storage – of minerals (Calcium and Phosphorous) and lipids ( yellow marrow)
4. Blood Cell Formation- hematopoiesis- occurs within the marrow of the bone.
5. Support- for the entire body; Individual bones provide a framework for attachment of soft tissues and organs.
• Matrix composed:
• 1. organic compound: protein- polysaccharides containing condroitin sulfate
• 2. Inorganic component: calcium, phosphate and calcium carbonate with small amount of mangnesium, fluoride, sulfate. The organic matter in bone matrix is type I collagen and ground substance
• Specialized CT
• •Cells of bone :
• –Osteoblasts
• –Osteocytes
• –Osteoclasts
• •Bone matrix
–Calcified material, lacunae
• •And more….
• –Canaliculi
• –Periosteum
• –Endosteum
Types of Bone Cells
• 1. Osteoblasts:(mononucleated) are responsible for synthesis of the organic components of bone matrix (type I collagen) .
• 2. Osteocytes: (mononucleated )which derive from osteoblasts lie in the lacunae situated between matrix, cylindrical matrix canaliculi house cytoplasmic processes of osteocytes.
• 3. osteoclasts:(multinucleated) are very large branched motile cells. Contain from 5 to 50 nuclei. Osteoclasts lie within enzymatically atched depressions in the matrix .
Structures of a Long Bone • Periosteum
– Outside covering of the diaphysis
– Fibrous connective tissue membrane
• Sharpey’s fibers – Secure periosteum to
underlying bone. – play important roles in bone
histogenesis and in the healing of fractures
• Arteries – Supply bone cells with
nutrients
Bones of the Human Body • The adult skeleton has 206 bones
• Two basic types of bone tissue
– Compact bone
• Long Bones
– - Spongy bone
• Short Bones
• Many open spaces
Compact bone
• Osteon (Haversian System) – A unit of bone
• Central (Haversian) canal – Opening in the center of an osteon
– Carries blood vessels and nerves
• Perforating (Volkman’s) canal – Canal perpendicular to the central canal
– Carries blood vessels and nerves
Microscopic Anatomy of compact Bone
• Canaliculi
– Tiny canals
– Radiate from the central canal to lacunae
– Form a transport system
Microscopic Anatomy of compact Bone
• Lacunae
– Cavities containing bone cells (osteocytes)
– Arranged in concentric rings
• Lamellae
– Rings around the central canal
– Sites of lacunae
Terminology of changes in bone
• osteopenia: decreased calcification or density of bone • • osteoporosis: progressive reduction in quantity of bone • • osteopetrosis: excessive formation of dense trabecular
bone • • osteosclerosis: abnormal hardening or eburnation of
bone • • osteohypertrophy: overgrowth of bone • • osteosarcoma: tumor of the bone • • osteochondrodysplasia: extreme bending of long bones • • osteochondroma (exostosis): benign cartilaginous neoplasma • • osteoblastoma: benign tumor of osteoblasts
Pathological changes of the joints • arthrosis: general term for degenerative affection of a joint • rheumatoid arthritis: systemic disease affecting connective tissue of joint, accompanied by inflammation and erosion of cartilage and bone due to synovial overgrowth • osteoarthritis: destruction of joints due to erosions of articular cartilage, accompanied by inflammation, eburnation of subchondral bone • gout: inflammation of the joint • synovitis: inflammation of synovial membrane • bursitis: inflammation of bursa (german: Schleimbeutel)