BIOS 4500 Lecture Notes - Lecture 23: Growth Hormone Deficiency, Laron Syndrome, Epiphyseal Plate
18 Nov 2016
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Document Summary
Endochondral ossification- proliferating cartilage is replaced by bone. Chondrocytes produce the mucopolysaccharides and collagen that constitute the cartilage matrix. Cartilage cells (chondrocytes) hypertrophy, become heavily vaculated, and degenerate as the. Migration of osteoblast progenitors from the marrow results in replacment of calcified cartilage. Estrogen at puberty is what causes the closure of the growth plates. Gh also stimulates chondrocyte production and responsiveness to igf-1. Igf-1 has paracrine and autocrin effects here to help mediate both production and. Stages of evolution of the somatomedin hypothesis: somatic growth is regulated by gh"s stimulation of hepatic igf-1 production-> Acts in an endocrine fashion on peripheral tissues to promote growth: gf has both direct effects on peripheral tissues and stimulates local igf-1. Production for autocrine/paracrine (a/p) action: besides gh having direct effects, sitmulating hepatic igf-1 production, and. Stimulates local igf-1 production, it also stimulates the formation of ternary. Igf binding complex, includign igfbp-3 and acid-labile subunit *stabilize igf-1 in the serum.
