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Title: Anat & Phys 10/31/06 Objectives: Class Topics
11/28/2018 Title: Anat & Phys 10/31/06 Objectives: To learn about bone physiology. Class Topics Review Skeletal Anatomy Test Notes Skeletal Physiology "We are an intelligent species and the use of our intelligence quite properly gives us pleasure. In this respect the brain is like a muscle. When it is in use we feel very good. Understanding is joyous.” Carl Sagan, 1979 Wednesday, November 28, :00 PM
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Class Assignments Due this class period Due next class period
11/28/2018 Class Assignments What By When Due this class period Due next class period Due in the future
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Functions of the Skeletal System
11/28/2018 Functions of the Skeletal System Protection Support Movement Storage of Calcium Blood Cell formation
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Parts of a long bone Diaphysis Epiphysis Periosteum
11/28/2018 Parts of a long bone Diaphysis shaft of the bone Epiphysis ends of bones Periosteum Dense irregular connective tissue lining the bones Articular cartilage Hyaline – lining the joint
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Diaphysis Made of compact bone Yellow marrow
11/28/2018 Diaphysis Made of compact bone Very strong and limited open space within Easily broken w/stress against long axis Yellow marrow Used to store fat (make blood cells in extreme conditions) found in medullary cavity hollow region of compact bone Lined with endosteum (thin dict membrane)
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Epiphysis Spongy bone (cancellous) more open spaces - like lattice
11/28/2018 Epiphysis Spongy bone (cancellous) thin layer of compact bone covering it more open spaces - like lattice Resists stress from many directions Red Marrow - Myeloid tissue Hematopoiesis - formation of blood cells erythropoiesis lymphopoiesis
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Walden Henry David Thoreau (1817 – 1862)
11/28/2018 Walden Henry David Thoreau (1817 – 1862) I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, to discover that I had not lived. I did not wish to live what was not life, living is so dear; nor did I wish to practice resignation, unless it was quite necessary. I wanted to live deep and suck out all the marrow of life, to live so sturdily and Spartan-like as to put to rout all that was not life, to cut a broad swath and shave close, to drive life into a corner, and reduce it to its lowest terms, and, if it proved to be mean, why then to get the whole and genuine meanness of it, and publish its meanness to the world; or if it were sublime, to know it by experience, and to be able to give a true account of it in my next excursion. “Dead Poets Society”
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11/28/2018 Bone Composition Bones are composed of bone tissue, cartilage, dense connective tissue, blood-forming tissue, blood vessels, and nerves Bone tissue (matrix) organic collagen inorganic hydroxyapatite
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Hydroxyapatite Mineral crystals made from calcium carbonate
11/28/2018 Hydroxyapatite Mineral crystals made from calcium carbonate calcium phosphate 2/3 of total weight of bone very hard and not very flexible
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Bone Cells Osteoblasts Osteocytes Osteoclasts found within periosteum
11/28/2018 Bone Cells Osteoblasts found within periosteum Actively produce matrix Osteocytes Osteoblasts that are trapped within the matrix trapped in lacunae Osteoclasts wander the tissue dissolve the mineral salts of matrix
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Microscopic Structure of Bone
11/28/2018 Microscopic Structure of Bone Lacunae spaces where the osteocytes reside Lamellae thin sheets of matrix in which the lacunae are found form circles around haversian canals or osteonic canals Haversian canals parallel to long axis of compact bone contain blood vessels
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Microscopic Structure of Bone (cont.)
11/28/2018 Microscopic Structure of Bone (cont.) How does the blood get from the vessel to the osteocytes? Canaliculi Each system around a haversian canal is called an osteon or haversian system osteocytes, lacuna, canaliculi, lamellae
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Microscopic Structure of Bone (cont.)
11/28/2018 Microscopic Structure of Bone (cont.) Volkmann’s canals blood vessels that run perpendicular to the long axis of the bone connect osteons Spongy bone trabeculae - thin plates (beams) of bone leaving space for red marrow
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From: http://www.mhhe.com/biosci/ap/histology_mh/canalicl.jpg
11/28/2018 From: From:
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Bone Development and Growth
11/28/2018 Bone Development and Growth Intramembranous Bones start formation 5th week after conception in between two embryonic membranes precursor (stem) cells turn to osteoblasts Spongy bone on the inside and compact on the outside
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Bone Development and Growth
11/28/2018 Bone Development and Growth Examples flat bones of skull mandibles clavicles Endochondral bones all other bones except those that are intramembranous Starts 6th week after conception
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Endochondral Bones Precursor cells change into chondroblasts
11/28/2018 Endochondral Bones Precursor cells change into chondroblasts forms hyaline cartilage template of skeletal system in cartilage Blood vessels penetrate cartilage stimulate chondroblasts to osteoblasts
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From: http://www.accessexcellence.org/RC/VL/xrays/1wrist/hanpelu.html
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Endochondral Bones Primary ossification center
11/28/2018 Endochondral Bones Primary ossification center center of diaphysis 1st place osteoblasts begin to work Work out toward each epiphysis 2ndary ossification center epiphysis forms spongy bone down to epiphyseal plate
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Intersititial Growth (length)
11/28/2018 Intersititial Growth (length) Occurs at epiphyseal plate chondrocytes divide and move material toward epiphysis Closer to the diaphysis older cartilage converts to bone - increase length of diaphysis Chondrocytes stop growing when acted upon by hormones from the pituitary gland
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Interstitial Growth Epiphyseal line
11/28/2018 Interstitial Growth Epiphyseal line old epiphyseal plate in those that have ceased growth
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Appositional Growth (width)
11/28/2018 Appositional Growth (width) Osteoblasts lay down bone on surface Osteoclasts dissolve bone Osteoblasts work harder than osteoclasts weight bearing exercise
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Bone Remodeling Continually broken down and built back up
11/28/2018 Bone Remodeling Continually broken down and built back up every 30 years each bone is completely renewed
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