Biomedical Engineering Reference
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Figure 3.2.
Hierarchical organization of collagen fiber.
2
consist of carefully arranged arrays of tropocollagen molecules,
whicharelong,rigidmolecules(300nmlongand1.5nmwide)com-
posed of three left-handed helices of peptides, as shown in Fig. 3.2.
Bones contain mostly type-I collagen, with some type-V colla-
gen, and the molecules are organized into collagen fibrils formed by
the assembly of tropocollagen molecules in a 3/4 staggered paral-
lel array.
2
The typicalhierarchical structure ofhuman bonesisillus-
trated in Fig. 3.3. Besides the hierarchical structure of collagen, the
hydroxyapatite(HA)crystalspresentintheformofplatesorneedles
areabout40-60nmlong,20nmwide,and1.5-5nmthick,
10
−
12
and
themineralphasepresentintheboneisnotadiscreteaggregationof
Figure 3.3.
Hierarchical structures in a human long bone.
12
,
14
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