Review Skeletal Anatomy Test

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Class Topics
Title Anat Phys 10/31/06
Objectives

• To learn about bone physiology.

• 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

Friday, November 20, 2020 122 PM
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Class Assignments
By When
What

• Due this class period
• Due next class period
• Due in the future

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Functions of the Skeletal System

• Protection
• Support
• Movement
• Storage of Calcium
• Blood Cell formation

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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
• 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)
• 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)

• 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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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
• calcium phosphate
• 2/3 of total weight of bone
• very hard and not very flexible

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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

• 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.)

• 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.)

• Volkmanns 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.octc.kctcs.edu/gcaplan/anat/Notes
/API20Notes20H20Skeletal20System.htm
From http//www.mhhe.com/biosci/ap/histology_mh/c
analicl.jpg
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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

• 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
• 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
• 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)

• 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
• old epiphyseal plate in those that have ceased
  growth

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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
• every 30 years each bone is completely renewed