KIN 3304 1nd Edition Lecture 4 Outline of Last Lecture I Composition of Bones II Periosteum and Lacunae and Osteo III Compact Bone vs Spongy Bone IV Anatomy of Bone V Periosteum VI Bone Development and Growth VII Ossification Outline of Current Lecture I Endochondral Ossification and its 7 Steps II Nutrient Artery and Vein III Metaphyseal Vessels and Periosteal Vessels IV Neural Innervation V Regulating Bone Growth VI Remodeling of Bone VII Bone Adaptation to Stress VIII Injury and Repair IX 4 Steps to Injury Repair X Aging Process Current Lecture I Endochondral Ossification and its 7 Steps a 6 weeks of embryonic development 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 b c d e f g h i j k i Proximal humerus femurs have formed 1 Composition entirely cartilage Skeleton continues to grow i Expansion of cartilage matrix 1 Interstitial growth ii More cartilage at outer surface 1 Appositional growth Step 1 i Cartilage enlarges 1 Chondrocytes near shaft increase in size 2 Surrounding matrix begins to calcify 3 Chondrocytes die disintegrate a Leaves cavities within cartilage Step 2 i Blood vessels grow around edges of cartilage 1 Cells become osteoblasts ii Layer of superficial bone wraps around cartilage Step 3 i Vessels penetrate into central region ii Fibroblasts differentiate into osteoblasts 1 Produce spongy bone iii Bone formation spreads along shaft toward end Step 4 i Bone grows remodels 1 Creates medullary cavity ii Shaft gets thicker iii Cartilage at ends replaced by bone STEPS 1 4 Ossification of bone i Bone develops forms STEPS 5 6 Lengthening of bone i Bone gets larger Step 5 i Capillaries osteoblasts migrate to epiphyses 1 Creates secondary ossification centers Step 6 i Epiphyses filled with spongy bone ii Articular cartilage remains exposed at joint cavity 1 Note incomplete cover on surface iii Thin cap remains exposed articular cartilage 1 Prevents bone bone contract in joint iv At metaphysis epiphyseal plate separates epiphysis from diaphysis Step 7 i Cartilage gets smaller closes 1 Known as epiphyseal closure l Increasing the Diameter of a Developing Bone picture II Nutrient Artery and Vein a Forms as blood vessels invade cartilage b Usually only 1 artery and 1 vein i Femur has 2 or more ii Enter through the nutrient foramen c Vessels penetrate the shaft reach medullary cavity III Metaphyseal Vessels and Periosteal Vessels a Metaphyseal Vessels TEST QUESTION i Supply blood to the inner diaphyseal surface of epiphyseal cartilage ii This is where bone is replacing cartilage b Periosteal Vessels i Blood vessels from periosteum incorporate into developing bone ii Provides blood to superficial osteons iii Also provides framework for lymphatic vessels IV Neural Innervation a Sensory nerves throughout bone b Skeletal injuries can be painful c Periosteum loaded with sensory nerves i Penetrate cortex with nutrient artery ii Endosteum medullary cavity epiphyses V Regulating Bone Growth a Growth requires constant Ca2 Phosphate Salts Mg other minerals b Dietary Vitamin A C are essential c Group of steroids collectively known as Vit D play role in Ca2 metabolism VI Remodeling of Bone a Process of simultaneously adding new bone and moving previously formed bone b Environmental stress can affect remodeling i Resistance training affects bone tendon and muscular attachment sites ii Know about Resistant training VII Bone Adaptation to Stress a Alter turnover recycling of minerals i Mineral crystals generate minute electrical fields following stress ii Osteoblasts are attracted to these fields 1 Produce bone once they arrive at site iii Can use electricity in fracture repair b Shapes and surface feature of bone reflect forces applied to them i As bone becomes stronger so do attachment points tendon sites etc VIII ii Heavily stressed bones become thicker stronger Injury and Repair a Damage from extreme loads impacts stress can cause fractures b Healing occurs provided blood supply and cellular components at the endosteum and periosteum survive c Final repair usually think stronger second fracture will likely occur elsewhere IX 4 Steps to Injury Repair a 1st Step i Hematoma developes ii Due to extensive bleeding at injury site b 2nd Step i External callus new mass of tissue of bone and cartilage stabilize after edge ii Internal callus forms as spongy bone forms network c 3rd Step i Cartilage of callus replaced by bone ii Spongy bone now unites broken bone iii Dead bone removed and replaced with new bone d 4th Step i Swelled area marks location of fracture ii Over time area remodeled iii Little evidence of fracture will remain X Aging Process a Bones become thinner weaker over time b Osteopenia inadequate ossification begins between age 30 and 40 i Osteoblast activity decreases ii Osteoclast activity remains the same iii 8 per decade loss in women 3 in male c Osteoporosis reduction in bone mass affects vertebrae jaw epiphyses more than other bones d Non weightbearing bones are more susceptible to this