IPHY 3410 1st Edition Lecture 6 Outline of Last Lecture 1 Distinguish between axial skeleton and appendicular skeleton 2 Identify the specific locations of cartilages in the adult body 3 Explain the functions of cartilage 4 Explain the functional properties of cartilage itself 5 Identify the unique characteristics and locations of hyaline fibro and elastic cartilages 6 Compare the three kinds of cartilage in terms of structure function and location 7 Explain why bones are considered organs Discuss the tissues comprising a bone 8 List and explain the main functions of the bony skeleton 9 Classify bones according to shape include several examples for each category 10 Describe the gross anatomy of a typical long bone 11 Describe where compact and spongy bones are located in a long bone 12 Differentiate the histology of compact and spongy bone 13 Explain why Prof Kram dislikes the term spongy bone 14 Explain why spongy bone and compact bones are found where they are in a long bone 15 Describe the structure function and relationship among central canal perforating canal lamellae lacuna and canaliculi Outline of Current Lecture 1 Diagram the microscopic structure of compact bone tissue include the osteon Haversian system central canal lamellae canaliculi and osteocytes 2 Explain the processes of endochondral and intramembranous bone formation 3 Explain the difference between the epiphyseal plate and the epiphyseal line 4 Explain the anatomy of epiphyseal growth areas Describe how the presence of epiphyseal plates determine whether bone is still growing in length 5 Explain the process of longitudinal bone growth 6 Describe the cause of osteoporosis osteomalacia and Paget s Disease if discussed in lecture and predict their pathologies 7 Summarize the organic and inorganic composition of bone 8 Describe the role of osteoblasts and osteoclasts in bone tissue remodeling 9 Identify the basic steps in the healing of a bone fracture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Current Lecture Epiphyseal Plate Figure 6 12 Organization of the cartilage within the epiphyseal plate of a growing long bone 80 X Resting quiescent zone Diaphysis grows in length pushes epiphysis away Growth proliferation zone Cartilage cells undergo mitosis Hypertrophic zone Older cartilage cells enlarge Calcifcation zone Matrix becomes calcifed cartilage cells die matrix begins deteriorating New bone New bone New bone Ossifcation osteogenic zone New bone formation is occurring http www personal psu edu staff m b mbt102 bisci4online bone bone5 htm Properties of Connective Tissue Not very cellular lots of extracellular matrix Few or zero cell junctions Extracellular matrix made up of ground substance and fibers except for blood Connective Tissue Proper and bone are o Vascularized o Innervated o But cartilage and blood are not Structure of a Long Bone Continued Endosteum contains dense CT osteoblasts and osteoclasts Perforating fibers bundles of collagen fibers that secure periosteum to bone Nutrient arteries pass through periosteum to supply bone with blood Periosteum o Dense irregular CT o Surrounds outside of bone except where articular cartilage is present o Portion in contact with compact bone is osteogenic Osteogenic osteoblasts and osteoclasts actively remodel the bone o Allow for increased outside diameter o Bones get longer and wider with growth and walls get thicker Bone Growth Organic portion of bone matrix osteoid is secreted by osteoblasts o Osteoid collagen fibers and ground substance Osteoblasts are trapped by calcified matrix and become osteocytes Osteoclasts secret HCl which breaks down old matrix Microscopic Structure of Compact Bone Endosteum lines bony canals and covers trabeculae Central canal center of osteon Lamellae rings of bone Osteocyte mature bone cell Lacuna space occupied by osteocyte Canaliculi channels that connect lacunae Perforating canal connect central canals Circumferential lamella layers rings of the diaphysis like rings of a tree trunk Figure 6 7 Microscopic structure of compact bone Lamella Central Haversian canal Osteocyte Osteon Canaliculus Circumferential lamellae Lamellae Lacuna b Central canal center of osteon Lamellae rings of bone Osteocyte mature bone cell Lacuna space occupied by osteocyte Central Haversian canal Perforating canal Endosteum Endosteum lines bony canals and covers trabeculae Canaliculi channels that connect lacunae Perforating canal connect central canals Circumferential lamella layers rings of the diaphysis like rings of a tree trunk Collagen fibers in adjacent lamella run perpendicular to one another o This increases torsional strength like plywood Classification of bones by shape Flat irregular and short bones o o o o o Spongy bone sandwiched between 2 layers of compact bone Like a foam core Spongy bone trabecular bone The space between trabeculae is filled with red bone marrow Trabeculae contain osteocytes and are lined by endosteum In trabecular bone the lamellae form flatter layers and are not arranged in rings Trabecular vs Compact bone o o bones Trabecular bone Lightweight allows space for red bone marrow Compact bone Dense heavy but is strong and strategically located along the outside of hollow tubes long Mechanisms of Bone Growth Intramembranous o Forms directly from embryonic tissue called mesenchyme o Most of the skull and clavicle form this way Endochondral o Hyaline cartilage forms first as a precursor to bone o Most bones of skeleton form this way Intramembranous Ossification o Mesencymal cells differentiate into osteoblasts o Osteoblasts contribute to matrix o Osteoblasts are then trapped by calcified matrix and become osteocytes o Blood vessels are woven into spongy bone and becomes lamellar bone compact bone Endochondral ossification of a long bone o Preexisting tissue is hyaline cartilage o Primary ossification is in the center of the diaphysis o Blood vessels spread into developing bone o At birth secondary ossification centers form in epiphyses o Epiphyseal plates will ossify when growth is complete o Remodeling occurs at both periosteal and endosteal surfaces Continues throughout a lifetime Stages of Healing a Bone Fracture Hemotoma formation Fibrocartilagnous callus formation o Dense CT with hyaline and fibrocartilage Bony callus formation o Trabeculae of spongy bone is the first to form Over several weeks new bone is