Abby Kaplan's Last Set of Bio Notes

Abby Kaplan's Last Set of Bio Notes - The Skeletal System...

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The Skeletal System 29/04/2008 00:27:00 Functions: Support Movement Protection Blood cell production Produces blood cells in red marrow Storage Minerals, fat (yellow blood marrow)  Structure: Comprises 3 types of connective tissue Bones Ligaments Cartilage The Human Skeleton: 206 bones and connective tissues that hold them together compact bone – very dense, forms shaft of long bones, what you see from the  outside o covered by periosteum that nourishes bone : contains blood vessels, nerves, cells that help w/ growth and  repair
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: what hurts when bone bruised or fractured spongy bone – found in small flat bones (skull, head ends of bone) in the shaft of long bones filled with yellow marrow 2 parts – axial and appendicular skeleton Bone is Living Tissue: compact bone contains structured unit called osteon, which consists of mature bone  cells called osteocytes osteon>osteocytes>lacuna>lacunae>central canal matrix: nonliving component; makes bone hard and resilient hard: mineral salt resilience: strands of strong elastic protein collagen Most of skeleton begins as cartilage: mature cells can not divide because of the matrix, but cartilage can transformation begins with the formation of a collar of a bone around shaft produced  by osteoblasts that secrete collagen and calcium salts osteoblasts can’t divide 2 structures of cartilage remain: at end for joints and growth plate  Hormones regulate bone growth: GH stimulates bone growth GH prompts liver to release growth factors to produce growth surge on growth plate 
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Thyroid hormones modify activity of GH to be proportionate At puberty, sex hormones stimulate growth When growth stops, the cartilage is gone and the bone ends fuse together Bone fractures  First thing after fracture, bone bleed -> formation of clot (hematoma) Connective tissue, fibroblasts, grow inward from periosteum and invade clot Fibroblasts secrete collagen fiber that form a callus which links the broken  ends Some fibroblasts transform into cartilage producing cells and secrete cartilage  into the callus Osteoblasts from periosteum invade the calus and transform the cartilage to bone As this happens, callus gets bigger but will return to normal size later We continue to undergo lifelong process of deposition and absorption Bone deposited by osteoblasts Osteoclasts break down bone by releasing minerals that are reabsorbed by body Occurs at different rates for different parts of body The degree of stress the bone is subjected to determines the rate
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This note was uploaded on 04/22/2009 for the course BIO 309D taught by Professor Jessicawandelt during the Spring '08 term at University of Texas at Austin.

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Abby Kaplan's Last Set of Bio Notes - The Skeletal System...

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