bio notes for test 3

bio notes for test 3 - 19:24:00 ← The Skeletal System ←...

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Unformatted text preview: 28/04/2008 19:24:00 ← The Skeletal System ← ← The Skeletal System: Functions • Support • Movement • Protection • Blood cell production • storage ← The Skeletal System: Structure • Comprises three types of connective tissue o Bones o Ligaments o Dense connective tissue Join bone to bone • Cartilage o Specialized connective tissue o Many functions • Bone Structure o Specialized connective tissue o Most of the mass of bone consists of nonliving extracellular matrix o Contain several types of living bone cells, nerves, and blood vessels o Most contain both compact and spongy tissue ← ← ← Bone Structure: Compact Bone • Very dense with few internal spaces • Hard, outer layer of bone • Osteon o Repeating structural unit of compact bone o Concentric rings of osteocytes surrounding a central canal • Osteocytes o Mature bone cells o Trapped in lacunae (cavity) within hardened matrix o Connected to one another via membrane extensions ← ← ← ← Bone Structure: Spongy Bone • Latticework of thin struts of bone with open areas between • Braces bone from within ← ← Bone Structure: Periosteum • Tough connective tissue layer that covers compact hone • Contains: o Blood vessels o Nerves o Bone cells that function in bone growth and repair ← ← Bone Development • Skeleton is first formed of cartilage • Ossification: replacement of cartilage by bone • Osteoblasts • Bone-forming cells • Secrete matrix components • Growth plate (epiphyseal plate) • Strip of cartilage cells that separates end of bone from shaft • Bone lengthening ← ← ← Hormones Regulate Bone Growth • Growth hormone • Thyroid hormones • Sex hormones ← ← iclicker • From which endocrine gland/organ is GH released? o Anterior pituitary in response to a signal from the hypothalamus ← ← Bone Remodeling • Bone is s dynamic tissue that undergoes constant replacement, remodeling, and repair • Bone deposition and absorption o Osteoblasts: deposit bone o Osteoclasts: secrete enzymes that breaks down bone ← ← iclicker • Which of the following is true? o When calcium is low, PTH is released ← ← Bone Remodeling: Regulation • Stress stimulates osteoblasts activity • Hormone regulation • Parathyroid hormone • Calcitonin • Osteoporosis • Progressive loss of bone mass ← ← Bone Repair • Multistep repair of bone fractures • Fibroblasts (connective tissue cells) /chondroblasts (one specific type of connective tissue cells - cartilage cells) • Osteoblasts • 1. Clot (hematoma) at site of break • 2. Cartilaginous callus o bridge the gap where the break occurred • 3. Bony callus ← ← The Human Skeleton • 206 bones and connective tissues that hold them together...
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bio notes for test 3 - 19:24:00 ← The Skeletal System ←...

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