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Chapter 6.2: Skeletal System. Bone Formation and Growth. Begins 6 weeks after fertilization Continues throughout adolescence Can continue until 25 Ossification—replacing tissue with bone. Intramembranous Ossification. Differentiate into bones Flat bones form this way. Figure 6.4.
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Bone Formation and Growth • Begins 6 weeks after fertilization • Continues throughout adolescence • Can continue until 25 • Ossification—replacing tissue with bone
Intramembranous Ossification • Differentiate into bones • Flat bones form this way
Endochondral Ossification • Most bones formed this way • Forms from hyaline cartilage models • Cartilage starts to calcify • Osteoblasts cover shaft • Blood vessels penetrate the cartilage • Bone of shaft thickens
Bone Growth • Women—stop by 18 • Men—stop by 20
Requirements for Bone Growth • Calcium • Comes from mom pre-birth • Mom loses bone mass while pregnant
Requirements cont… • Vitamin D3 • Through vitamins or UV rays • Processed by liver • Allows calcium and phosphate to be absorbed
Requirements cont… • Rickets • Soft and bendable bones in kids • Result of vitamin D deficiency • Bowlegged appearance
Requirements cont… • Vitamins A and C • Scurvy—lack of vitamin C • Decreased osteoblast activity • Weak and brittle bones