Lecture 19a - Supplementary Information on X-linked Disorders and Disorders Due to Chromosome Numb

Lecture 19a - Supplementary Information on X-linked Disorders and Disorders Due to Chromosome Numb

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1 Lecture 19a Supplementary information on X-linked disorders and disorders due to chromosome numbers You are not responsible for this information. It will not be on the exam. Bone and calcium and the regulation of calcium Bone Cells • Osteoblast – young “teenager” bone cell – has a “blast” laying down bone – very active • Osteocyte – mature bone cell – sits there and does not do very much. • Osteoclast – urban renewal bone cell – destroys bone so new bone can be formed. • Stem cell – divides into either osteoblasts or osteoclasts Bone Structure Next Slide
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2 The Osteon Osteocyte in a lacuna Haversian canal Boundary of lamella The Osteocyte This is an electron micrograph of an osteocyte in its lacuna (Latin for little lake). Note the projections (called osteocytic processes) of the cell through the canaliculi (little canals in Latin). Osteocytes keep in touch will other osteocytes in an osteon. If they retract these processes, they die. Canaliculus Osteocytic process Lacuna Nucleus of the osteocyte The Canaliculi go to and from the Haversian Canal An osteocytic process in its canaliculi goes right to the Haversian canal. Capillary Capillary Dr. David T. Morgan The beautiful electron micrographs of bone in this lecture were all done by Dave Morgan, Professor of Histology, University of Colorado School of Medicine in Denver All sane professors have a balanced life outside of the laboratory and classroom, and here Dave is seen with his falcon and dog in the mountains west of Boulder, Colorado. Below is a picture of the Flatirons (the Front Range of the Rockies) at Boulder. Photo and electron micrographs from visualhistology website
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3 Diffusion is the key Capillary Capillary Nutrients and calcium for storage diffuse from the capillaries through the canaliculi to the osteocytes; calcium released from storage travels in the reverse direction. The Functional Unit of Bone: The Osteon The osteon is the functional unit of bone Its center is the Haversian canal named after Clopton Havers (1655-1702) Each lamella is composed of collagen fibres arranged at a different angle. This is like plywood. The number of lamellae determines the strength of the bone. The Haversian canal has an artery, vein, nerves. Nutrients and metabolic waste products go through the arteries and veins . Model from the University of Wisconsin Plywood vs. Plank board Photo by Fotosearch Plywood – in each layer, the wood fibers are arranged at different angles. In a plank (right), the fibers are all one direction, giving little strength to a board. Lamellae in bone can be strong – like plywood – or weak like plank board. Bone – is living and changing • Every year your bone somewhere is being broken down and replaced. • This is called remodeling (just like in a
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This note was uploaded on 06/10/2008 for the course BIOL BIOL-1F25 taught by Professor Peery during the Spring '08 term at Brock University.

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Lecture 19a - Supplementary Information on X-linked Disorders and Disorders Due to Chromosome Numb

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