Inorganic Matrix removed the bone becomes flexible cannot resist compression 65 hydroxyapatite crystals Organic Matrix bone shatters easily if removed 35 collagen osteoid ground substance Osteoblast immature cells forms bone matrix after trapped become osteocytes Osteoclast breaks down bone reabsorbs bone site of parathyroid hormones Osteocyte mature bone cells maintains bone tissue bone remodeling derived from osteoblasts communicates via gap junctions Osteogenic cells stem cell generates less prevalent when growth plate grows becomes osteoblasts Skeletal muscle fiber Endomysium extracellular matrix surrounding a single fiber Perimysium connective tissue CT surrounding a cluster of many fibers Tendon CT connecting muscle to bone Epimysium CT surrounding many fascicles Function contraction to generate force produce body movement heat production Many sarcomeres in one myofibril when all sarcomeres shorten so does the myofibril Many Myofibrils in one muscle fiber when all myofibrils shorten so does the muscle cell Optimal actin myosin overlap will produce maximal contraction tension Resting state tropomyosin prevents myosin from binding to actin Calcium binds to troponin leading to release of tropomyosin from the myosin binding sites Crossbridge cycle is repeated to contract the sarcomere Muscle tension contraction relaxation Wave summation fused tetanus extended period of time heavy object no time to relax stimulated abt 50x per sec muscle fatigue unfused tetanus allowed to relax stim 80 100x per sec generates sustained contraction maximal tension Length tension relationship Overly shortened 85 of max Tension too much overlap no room for movement Overly stretched 90 of max tension too little overlap hard for myosin to grip actin Isometric muscle remains same length tension varies external load is equal to the force generated by muscle Isotonic tension stays the same muscle changes length enough tension is generated to move a load Isotonic Concentric muscle tissue shortens force generated is greater than external load Isotonic Eccentric muscle tissue lengthens force generated by muscle is less than the load elastic filaments stretch Hypotonia low skeletal muscle tone Hypertonia very high muscle tone Chondrocytes are cells of cartilage that initiate bone formation differentiate into osteogenic cells osteoblasts Growth hormones Estrogen Androgens impact bone growth Testosterone appositional growth bone deposition Estrogen longitudinal growth stronger than T inhibits osteoclast activity Calcium parathyroid hormones Ca release into bloodstream calcitonin promotes deposition of Ca into bone Vita D promotes Ca uptake in intestines Vita C required for collagen synthesis Vita K glycoprotein production binds Ca Protein collagen synthesis Remodeling continuous formations bone loss stress placed on bones tension compression Deposition formation of new bone caused by exercise testosterone tension vitamin consumption osteoblast activity osteoclast activity Resorption destruction of old bone pressure placed on bones parathyroid hormones in blood calcium ion concentration osteoblast activity osteoclast activity Skeletal muscle fiber features long thin cylinders striated multinucleated Sarcolemma plasma membrane of a muscle fiber Myofibril proteins involved in cell contraction Sarcoplasmic reticulum SR smooth ER that stores releases Ca T tubules inward extensions of sarcolemma that form a tunnel like network filled with extracellular fluid Terminal cisternae enlarged portions of SR on either side of T tubule Titin stabilizes thick filament elastic resistive to stretching provides elasticity Myosin protein clusters thick filament contractile head where thin filaments bind ATP dependent Actin subunits of contractile protein with an active site that binds myosin Tropomyosin ropelike protein that spirals around actin covers active site at rest Troponin holds tropomyosin in place To exert tension thick thin filaments must overlap Sliding Filament Theory myosin heads bind to actin begin sliding thin filaments slide past thick ones I H band change in length Muscle relaxation Acetylcholinesterase degrades the remaining ACh final repolarization begins Sarcolemma returns to resting membrane potential 90mV Ca channels in the SR close Ca are pumped back into SR returning Ca conc in the cytosol to its resting level troponin tropomyosin block active sites of actin muscle relaxes ATP is required for relaxation Fast Twitch Type 1 high myosin ATPase activity found in eyes moves quickly large in diameter tire quickly Slow Twitch Type 2 low myosin ATPase activity found in slow muscles sustained contractions back muscles posture ATP regulates the speed small intermediate in diameter extended contraction IIa fast oxidative glycolytic walking writing light red color IIx fast glycolytic light pink white color heavy lifting sprinting Myoplasticity muscle will alter its structure to support its function Endurance more reps lighter loads swim jog biking Resistance fewer reps higher load strength or resistance training Sedentary physical inactivity Hypertrophy enlargement of an organ tissue cell Atrophy in the size of a cell or organ Muscle fatigue inability to maintain a level or intensity during exercise depletion of metabolites reduced O2 supply to muscle fibers greater glycolysis dependency accumulation of Ca ADP Po4 high heat high altitude EPOC restore homeostasis elevated body temp ion concentrations restores blood pH Muscle Cell Properties Contractility ability to contract Excitability respond to stimuli Conductivity electrical membrane change Distensibility stretch without damage Elasticity stretch retain shape Skeletal long cylindrical striated multinucleated attaches to skeleton voluntary produces body movement Cardiac short wide branching striated intercalated discs 1 2 nucleus heart involuntary heart beating Smooth thin smooth joined by gap junctions 1 nucleus walls of hollow organs skin eyes involuntary changes diabetes shape lens of pupil Immediate energy needs creatine kinase ADP ATP glycolytic catabolism 1 glucose 2 ATP aerobic 2 pyruvate enter anaerobic 2 pyruvate converted to 2 lactate oxidative catabolism Long term energy needs oxidative catabolism Myoglobin oxygen carrying protein found in cytosol of muscle cells Erythrocyte RBC large surface area to volume ratio good for gas exchange mature cells are nuclear no metabolism of protein synthesis cytoplasm made of enzymes hemoglobin Hb Erythropoiesis