BIOL 1412 Lecture Notes - Lecture 9: Endochondral Ossification, Intramembranous Ossification, Hyaline Cartilage
1 May 2018
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TOPIC IX: SKELETAL SYSTEM
A) Skeletal System Overview:
Functions:
1) support
2) protection of vital organs
3) attaches muscles + allows movement
4) red marrow produces rbc, wbc
5) stores Ca++
B) Bone Ossification:
- before week 8, skeleton of embryo constructed of fibrous membranes + hyaline
cartilage
- bone formation begins at ~8th week → 20 years
- types:
1) Intramembranous ossification
- flat bones e.g. some skull bones, mandible, clavicle
- develop from fibrous CT membrane
- process:
- osteoblasts produce spongy bone along CT fibres
- periosteum forms and then osteoblasts under it lay down
compact bone
- fontanels = unossified membranes in the skull that remain at birth
2) Endochondral ossification (most bones)
- hyaline cartilage used as a model (similar shape) for bone
construction – then ossifies to form spongy bone
- periosteum forms and the osteoblasts beneath lay down compact bone
- articular cartilage + epiphyseal plates = cartilage that has not ossified
C) Bone Growth (postnatal):
1) Growth in length
- = endochondral growth - at epiphyseal plates
- process:
- cartilage grows → matrix near diaphysis becomes bone
- growth in length stops when epiphyseal plate ossifies into epiphyseal
line (closure)
2. Growth in diameter
= appositional growth
- process:
find more resources at oneclass.com
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Document Summary
1: support, protection of vital organs, attaches muscles + allows movement, red marrow produces rbc, wbc, stores ca++ cartilage. Topic ix: skeletal system: skeletal system overview: Functions: bone ossification, bone growth (postnatal), growth in length. Before week 8, skeleton of embryo constructed of fibrous membranes + hyaline. Bone formation begins at ~8th week 20 years. Flat bones e. g. some skull bones, mandible, clavicle. Fontanels = unossified membranes in the skull that remain at birth: intramembranous ossification. Osteoblasts produce spongy bone along ct fibres. Periosteum forms and then osteoblasts under it lay down compact bone: endochondral ossification (most bones) Hyaline cartilage used as a (cid:862)model(cid:863) (similar shape) for bone construction then ossifies to form spongy bone. Periosteum forms and the osteoblasts beneath lay down compact bone. Articular cartilage + epiphyseal plates = cartilage that has not ossified. = endochondral growth - at epiphyseal plates. Cartilage grows matrix near diaphysis becomes bone.
