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Skeletal System, Know these stages, Osteoclasts - break down calcified…
Skeletal System
Bone Classification by Shape:
Long
Parts: Epiphysis, Diaphysis, Metaphysis, Articular cartilage, Periosteum, Compact bone, spongy bone, Trabeculae, Medullary cavity, Endosteum, Bone marrow
Short
Flat
Irregular
Microscopic Structure of Bone
Canaliculi - passageways
Lacunae - chambers for osteocytes
Osteocytes - bone cell
Extracellular matrix of bone is mostly: collagen fibers and inoraginc salts
Blood Cell Formation
Hematopoiesis - Blood cell formation
blood cell production occurs in - red bone marrow
with age some red bone marrow is replaced by - yellow bone marrow, which stores fat but does not produce blood cells
Inorganic Salt Storage
Most abundant - hydroxyapatite (calcium phosphate)
Other salts: magneusium ions, sodium ions, potassium ions, carbonate ions.
osteoporosis - a condition that result from loss of bone mineralization
blood calcium levels are regulated by
Calcitonin - decrease blood calcium (tone it down) using ostyoblasts
Parathyroid hormone - increase blood calcium levels using ostyoclasts
Bone Developemnt, growth and repair
Endochondral Ossification - Bones form from hyaline cartilage models
hyaline cartilage > Chondrocytes enlarge > Lacunea grow > Matrix breaks down > chondrocytes die > Osteoblast > osteocytes
Osteogenesis imperfecta - defect in which bones are brittle
Intramembranous Ossification - bones form between sheets of primitive CT
mesenchymal cells > osteoblasts > matrix > osteocytes in lacunae > Mesenchyme on outside forms periosteum
Epiphyseal Plate - region where bone grows in length (Cartilaginous cells of epiphyseal plate form 4 layers)
zone of proliferating cartilage
zone of hypertrophic cartilage
zone of resting cartilage
zone of calcified cartilage
Homeostasis of bone tissue
Bone Resorption - Removal of bone by osteoclasts
bone deposition - formation of bone by osteoblasts
Bone remodeling - occurs throughout life
Fractures
Classification by cause: traumatic, spontaneous or pathologic
Classification by nature of break: simple (closed), Compound (open)
Steps in Fracture Repair: Hematoma, Cartilaginous soft callus, bony hard callus, remodeling
affecting factors: vitamins D A C, growth hormone, thyroid hormone, parathyroid hormone, sex hormones, physical stress
Many tissues: bone tissue, cartilage, dense CT, blood and nervous tissue
2 divisions: Axial and Appendicular
Compact Bone: has osteons, Lamellae, and Central canal. (Strong and solid)
Spongy Bone: has trabeculae. (somewhat flexible)
adults have 206 bones
Know these stages
Osteoclasts - break down calcified matrix. Osteoblasts - then invade replacing cartilage with bone tissue