KIN 3304 1nd Edition Lecture 4 Outline of Last Lecture I. Composition of BonesII. Periosteum and Lacunae and OsteoIII. Compact Bone vs. Spongy BoneIV. Anatomy of BoneV. PeriosteumVI. Bone Development and GrowthVII. OssificationOutline of Current Lecture I. Endochondral Ossification and its 7 StepsII. Nutrient Artery and VeinIII. Metaphyseal Vessels and Periosteal VesselsIV. Neural InnervationV. Regulating Bone GrowthVI. Remodeling of BoneVII. Bone Adaptation to StressVIII. Injury and Repair IX. 4 Steps to Injury RepairX. Aging ProcessCurrent LectureI. Endochondral Ossification and its 7 Stepsa. 6 weeks of embryonic developmentThese 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.i. Proximal humerus, femurs have formed1. Composition entirely cartilageb. Skeleton continues to growi. Expansion of cartilage matrix1. Interstitial growthii. More cartilage at outer surface1. Appositional growthc. Step 1i. Cartilage enlarges1. Chondrocytes near shaft increase in size2. Surrounding matrix begins to calcify3. Chondrocytes die, disintegratea. Leaves cavities within cartilaged. Step 2i. Blood vessels grow around edges of cartilage 1. Cells become osteoblastsii. Layer of superficial bone wraps around cartilagee. Step 3i. Vessels penetrate into central regionii. Fibroblasts differentiate into osteoblasts1. Produce spongy boneiii. Bone formation spreads along shaft toward endf. Step 4i. Bone grows, remodels1. Creates medullary cavityii. Shaft gets thickeriii. Cartilage at ends replaced by boneg. STEPS 1-4: Ossification of bonei. Bone develops, formsh. STEPS 5-6: Lengthening of bonei. Bone gets largeri. Step 5i. Capillaries, osteoblasts migrate to epiphyses1. Creates secondary ossification centersj. Step 6i. Epiphyses filled with spongy boneii. Articular cartilage remains exposed at joint cavity1. Note incomplete cover on surfaceiii. Thin cap remains exposed (articular cartilage)1. Prevents bone; bone contract in jointiv. At metaphysis, epiphyseal plate separates epiphysis from diaphysisk. Step 7i. Cartilage gets smaller, closes1. Known as epiphyseal closurel. Increasing the Diameter of a Developing Bone (picture)II. Nutrient Artery and Veina. Forms as blood vessels invade cartilageb. Usually only 1 artery and 1 veini. Femur has 2 or moreii. Enter through the nutrient foramenc. Vessels penetrate the shaft, reach medullary cavityIII. Metaphyseal Vessels and Periosteal Vesselsa. Metaphyseal Vessels (TEST QUESTION)i. Supply blood to the inner (diaphyseal) surface of epiphyseal cartilageii. This is where bone is replacing cartilageb. Periosteal Vesselsi. Blood vessels from periosteum incorporate into developing boneii. Provides blood to superficial osteonsiii. Also provides framework for lymphatic vesselsIV. Neural Innervationa. Sensory nerves throughout boneb. Skeletal injuries can be painfulc. Periosteum loaded with sensory nervesi. Penetrate cortex with nutrient arteryii. Endosteum, medullary cavity, epiphysesV. Regulating Bone Growtha. Growth requires constant Ca2+, Phosphate Salts, Mg, other mineralsb. Dietary Vitamin A, C – are essentialc. Group of steroids collectively known as Vit. D play role in Ca2+ metabolismVI. Remodeling of Bonea. Process of simultaneously adding new bone and moving previously formed boneb. Environmental stress can affect remodelingi. Resistance training affects bone, tendon, and muscular attachment sitesii. Know about Resistant trainingVII. Bone Adaptation to Stressa. Alter turnover/recycling of mineralsi. Mineral crystals generate minute electrical fields following stressii. Osteoblasts are attracted to these fields1. Produce bone once they arrive at siteiii. Can use electricity in fracture repairb. Shapes and surface feature of bone reflect forces applied to themi. As bone becomes stronger, so do attachment points (tendon sites, etc.)ii. Heavily-stressed bones become thicker, strongerVIII. Injury and Repair a. Damage from extreme loads, impacts, stress can cause fracturesb. Healing occurs provided blood supply and cellular components at the endosteumand periosteum survive c. Final repair usually think, stronger; second fracture will likely occur elsewhereIX. 4 Steps to Injury Repaira. 1st Stepi. Hematoma developesii. Due to extensive bleeding at injury siteb. 2nd Stepi. External callus (new mass of tissue) of bone and cartilage stabilize after edgeii. Internal callus forms as spongy bone forms networkc. 3rd Stepi. Cartilage of callus replaced by boneii. Spongy bone now unites broken boneiii. Dead bone removed and replaced with new boned. 4th Stepi. Swelled area marks location of fractureii. Over time, area remodelediii. Little evidence of fracture will remainX. Aging Processa. Bones become thinner, weaker over timeb. Osteopenia (inadequate ossification) begins between age 30 and 40i. Osteoblast activity decreasesii. Osteoclast activity remains the sameiii. ~8% per decade loss in women, 3% in malec. Osteoporosis (reduction in bone mass) affects vertebrae, jaw, epiphyses more than other bonesd. Non weightbearing bones are more susceptible to