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Bull Harrier: Bone


Another long lecture at 70 minutes.



Arthro is joint.  Chrondro is cartilage.  Osteo is bone.  Spondylo is vertebra.  Articulu is joint. 

Bone is dynamic, continually making and destroying itself. 

Skeletal System = bones, cartilage, ligaments, joints

Functions: support, protection, movement, mineral storage, hematopoiesis, triglyceride storage

Osseous tissue is CT.  Matrix is hardened by Ca deposition. 

Shapes: long short(talus) flat(sternum) irregular (vertebra)

Bones are compact or spongy.  The medullary cavity is full of marrow.  The diaphysis is the middle, the ends are the epiphysis.  Periosteium is a covering on the outside of the bone.  The epiphyseal line is the limit of growth. 

Tuberocity are large rounded projections, a spine is a  sharp slender pointed projection.  Foramen magnum is the bottom of the skull. 

Endosteum is the inside of the bone.  Articular cartilage is found on the outer parts of the epiphesis.  Yellow bone marrow is the storage of triglycerides in the MC. 

Osteoblasts build bone.  Osteogenic cells are stem cells that give rise to different cell types.  Osteoclasts destroy the matrix.  Osteocytes are former osteoblasta that are trapped in the matrix they deposited.  Lacunae are small cavities or lakees.  Canaliculi are narrow channels that connect lacunae.

Bone matrix is 1/3 organic, 2/3 inorganic.

Inorganic = 85% hydroxyapatite, 10 Ca CO3, 5% random ions.

The basic structure of compact bone is the osteon.  Trabecula follow lines of stress.  Spongey bone is more porous. 

Red bone marrow produces RBCs.  Spongy bone.  Yellow bone marrow is the home of fats. 

Intramembanous ossification: skull formation.  Flat bones, fibrous sheet, no cartilage necessary.

Endochondral ossification: most common method of osteogenesis.  Hyline cartilage, epiphyseal plate forms. 

Bone Formation

proliferation, hypertrophy, calcification, ossification.

Achondroplastic dwarfism failure of cartilage in long bones.

Bone widening bone growing in diameter. 

Wolf’s Law of Bones: Architecture is determined by mechanical stresses. 

Ectopic ossication is abnormal calcification of tissues. 

Osteoblasts secrete collagen fibers.  Osteoclasts secrete acid phosphatase. 

Hypocalcemia is a deficiency.  Tetany is an inability of muscle to relax. 

Hypercalcemia is too much blood calcemia.  Less excitable nerve and muscle tissue. 

Calcitrol increases blood Ca levels.  Secreted by the thyroid.  Inhibits osteoclasts, stimulates osteoblasts.  `

PTH increases Ca blood levels.  Increases Ca reabsorbtion in the kidneys, increase calcitriol production.

Stress fractures are caused by abnormal trauma.  Pathological fractures are caused by disease that weaken the bone. 


Usually takes 8 to 12 weeks…

Hematoma/granulation tissue

Soft Callus

Hard Callus


Osteomalacia – calcium not deposited, bones not mineralized.  Rockets – osteomalacia in kids.  Low Ca intake or lack of vitamin D.

Osteoporosis is the most common bone disease.  Abnormally brittle.  Hip fractures are common, post menopausal women at the greatest risk. 

Paget’s Disease is excessive deposition and resorption.  Usually localized. 




peat, lignite, bitumen, sub bitumen, anthicite

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