Skeleton System Notes:
Human Skeleton:
206 bones
Axial and appendicular
Cartilages:
o Hyaline cartilage: articular and costal cartilages
o Fibrocartilage: pressure absorbing discs
Connective Tissue Proper:
o Major contributor to all synovial joint capsules
o Ligament: bone to bone
o Tendon: muscle to bone
Skeletal System Functions:
Support
Protection
Movement (levers)
Mineral storage (Ca2+)
Blood cell formation (hemopoiesis)
Model for bone growth
Articulations
Classification of Bones:
Flat bones:
o Ex: frontal bone
Irregular bones:
o Ex: vertebrae
Sesamoid bones:
o Ex: patella
Short bones:
o Ex: tarsals and carpals
Long bones:
o Ex: femur and humerus
Composition of Bones:
Inorganic Constituents of Bone:
o Calcium hydroxyapatite mineral matrix
Calcium carbonate and calcium phosphate
About 60-70% dry bone weight
o Water
Accounts for about 25-30% total bone weight
Organic Constituents of Bone:
o Collagen fibers (specifically collagen type IV)
, o Epithelial, vascular and nervous tissues
o Bone cells (osteocytes, osteoblasts, osteoclasts)
Bone Remodeling:
Bone is a very “dynamic” tissue
In response to mechanical loads, stresses or strains, osteoclasts and osteoblasts
breakdown and rebuild bony tissue to accommodate
Wolff’s Law
Forces on Bone:
Compressive Strength:
o Ability to resist compressive forces
o Due to the mineral matrix of bony tissue
Tensile Strength:
o Ability to resist tension forces
o Due to the collage component of bone
Functions of Skeletal Soft Tissues:
Binding and support
Protection
Articulations (reduced friction)
Flexibility
Bone Cells:
Osteogenic cell:
o stem cell
Osteoblast:
o Matrix-synthesizing cell responsible for bone growth
Osteocyte:
o Mature bone cell that maintains the bone matrix
Osteoclast:
o Bone-reabsorbing cell
Ossification:
Creation of bone
Osteogenesis:
Bone can be “created” one of two ways:
Intramembranous Ossification:
o Formation of bone within a membrane
o Most skull and few other bones form this way
Endochondral Ossification:
o Formation of bone within a cartilage precursor
Human Skeleton:
206 bones
Axial and appendicular
Cartilages:
o Hyaline cartilage: articular and costal cartilages
o Fibrocartilage: pressure absorbing discs
Connective Tissue Proper:
o Major contributor to all synovial joint capsules
o Ligament: bone to bone
o Tendon: muscle to bone
Skeletal System Functions:
Support
Protection
Movement (levers)
Mineral storage (Ca2+)
Blood cell formation (hemopoiesis)
Model for bone growth
Articulations
Classification of Bones:
Flat bones:
o Ex: frontal bone
Irregular bones:
o Ex: vertebrae
Sesamoid bones:
o Ex: patella
Short bones:
o Ex: tarsals and carpals
Long bones:
o Ex: femur and humerus
Composition of Bones:
Inorganic Constituents of Bone:
o Calcium hydroxyapatite mineral matrix
Calcium carbonate and calcium phosphate
About 60-70% dry bone weight
o Water
Accounts for about 25-30% total bone weight
Organic Constituents of Bone:
o Collagen fibers (specifically collagen type IV)
, o Epithelial, vascular and nervous tissues
o Bone cells (osteocytes, osteoblasts, osteoclasts)
Bone Remodeling:
Bone is a very “dynamic” tissue
In response to mechanical loads, stresses or strains, osteoclasts and osteoblasts
breakdown and rebuild bony tissue to accommodate
Wolff’s Law
Forces on Bone:
Compressive Strength:
o Ability to resist compressive forces
o Due to the mineral matrix of bony tissue
Tensile Strength:
o Ability to resist tension forces
o Due to the collage component of bone
Functions of Skeletal Soft Tissues:
Binding and support
Protection
Articulations (reduced friction)
Flexibility
Bone Cells:
Osteogenic cell:
o stem cell
Osteoblast:
o Matrix-synthesizing cell responsible for bone growth
Osteocyte:
o Mature bone cell that maintains the bone matrix
Osteoclast:
o Bone-reabsorbing cell
Ossification:
Creation of bone
Osteogenesis:
Bone can be “created” one of two ways:
Intramembranous Ossification:
o Formation of bone within a membrane
o Most skull and few other bones form this way
Endochondral Ossification:
o Formation of bone within a cartilage precursor
