IPHY 3410 1st Edition Lecture 6 Outline of Last Lecture 1) Distinguish between axial skeleton and appendicular skeleton2) Identify the specific locations of cartilages in the adult body3) 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 LectureEpiphyseal PlateFigure 6.12 Organization of the cartilage within the epiphyseal plate of a growing long bone (80 X). Growth (proliferation) zone *Cartilage cells undergo mitosis Resting (quiescent) zone Hypertrophic zone -Older cartilage cells enlarge Ossifcation (osteogenic) zone -New bone formation is occurring Calcifcation zone -Matrix becomes calcifed; cartilage cells die; matrix begins deteriorating New bone New bone New bone Diaphysis grows in length, “pushes” epiphysis away 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 Vascularizedo Innervatedo But cartilage and blood are notStructure 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- Periosteumo Dense irregular CTo Surrounds outside of bone except where articular cartilage is presento Portion in contact with compact bone is osteogenic Osteogenic – osteoblasts and osteoclasts actively remodel the boneo Allow for increased outside diametero Bones get longer and wider with growth and walls get thickerBone 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 matrixMicroscopic 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 (b) Endosteum Central (Haversian) canal Central (Haversian) canal Canaliculus Lacuna Lamella Osteocyte Osteon Circumferential lamellae Lamellae Perforating canal 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 Endosteum: lines bony canals and covers trabeculae Circumferential lamella: layers (rings) of the diaphysis (like rings of a tree trunk) - Collagen fibers in adjacent lamella run perpendicular to one anothero This increases torsional strength – like plywoodClassification of bones by shape- Flat, irregular, and short boneso Spongy bone sandwiched between 2 layers of compact boneo Like a “foam core” - Spongy bone = trabecular bone o The space between trabeculae is filled with red bone marrowo Trabeculae – contain osteocytes and are lined by endosteumo In trabecular bone, the lamellae form flatter layers and are not arranged in ringsTrabecular vs. Compact bone- Trabecular bone o Lightweight, allows space for red bone marrow- Compact bone o Dense (heavy) but is strong and strategically located along the outside of “hollow tubes” (long bones)Mechanisms of Bone Growth- Intramembranouso Forms directly from embryonic tissue called mesenchymeo Most of the skull and clavicle form this way- Endochondralo Hyaline cartilage forms first as a precursor to boneo Most bones of skeleton form this way- Intramembranous Ossificationo Mesencymal cells differentiate into osteoblastso Osteoblasts contribute to matrixo Osteoblasts are then trapped by calcified matrix and become osteocyteso Blood vessels are “woven” into spongy bone and becomes “lamellar bone” (compact bone)- Endochondral ossification of a long boneo Preexisting tissue is hyaline cartilageo Primary ossification is in the center of the diaphysiso Blood vessels spread into developing boneo At birth: secondary ossification centers form in epiphyseso Epiphyseal plates will ossify when growth is completeo Remodeling occurs at both periosteal and endosteal surfaces Continues throughout a