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Bone and Muscle Review CHAPTERS 6 AND 9 Cartilage in external ear Cartilage in Intervertebral disc Cartilages in nose Articular Cartilage of a joint Epiglottis Thyroid cartilage Cricoid cartilage Larynx Trachea Lung Costal cartilage Respiratory tube cartilages in neck and thorax Pubic symphysis Meniscus (padlike cartilage in knee joint) Articular cartilage of a joint Bones of skeleton Axial skeleton Appendicular skeleton Cartilages Hyaline cartilage CT Elastic cartilage CT Fibrocartilage CT Copyright © 2010 Pearson Education, Inc. Figure 6.1 Copyright © 2010 Pearson Education, Inc. Figure 6.2 Last Lecture We Covered… • Six Functions of Bone: • 1. Protection • 2. Support • 3. Movement • 4. Storage of minerals • 5. Blood cell formation (hematopoiesis) • 6. Fat storage Copyright © 2010 Pearson Education, Inc. Spongy bone inside a flat bone Spongy bone (diploë) Compact bone Trabeculae Copyright © 2010 Pearson Education, Inc. Figure 6.5 Articular cartilage Proximal epiphysis Compact bone Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) (b) Diaphysis Distal epiphysis (a) Copyright © 2010 Pearson Education, Inc. Figure 6.3a-b Structures in the central canal Artery with capillaries Vein Nerve fiber Osteons have many layers called lamella Lamellae Collagen fibers run in different directions Twisting force Copyright © 2010 Pearson Education, Inc. Figure 6.6 Bone cells • Osteoprogenitor/Osteogenic cells • make osteoblasts • Osteoblasts • secrete osteoid, make bone • Osteocytes • mature bone cells inside lacunae • Osteoclasts • absorb bone Copyright © 2010 Pearson Education, Inc. Osteocytes are connected by canaliculi (little canals) through which their “arms” pass nutrients to cells far from the blood in the central canal, and waste back. blood Copyright © 2010 Pearson Education, Inc. Last Lecture We Covered… • Formation of bone: • Osteoblasts secrete collagen fibers and proteoglycan gel (like a slug’s slime trail) • Calcium ions (Ca2+) arrive from blood and bind to collagen • Phosphate (PO4-) arrives from blood and binds to Calcium • Hydroxyappatite crystals form (bone minerals) and hardens matrix into bone. Copyright © 2010 Pearson Education, Inc. What we covered last time… • Two Types of Ossification • Intramembranous Ossification • Spongy bone forms first from a primary ossification center between two thick CT membranes • Endochondral Ossification • Compact bone forms first around cartilage as bone collar. Primary and secondary ossification centers turn existing cartilage into bone. Copyright © 2010 Pearson Education, Inc. Intramembranous ossification of flat bones CT stem cell Collagen fiber Ossification center Osteoid Osteoblast 1. Early “stem” cells make a collagen sheet, or membrane. 2. Inside this membrane, osteoblasts form from other stem cells Copyright © 2010 Pearson Education, Inc. Figure 6.8, (1 of 4) Intramembranous ossification Osteoblast Osteoid Osteocyte Newly calcified bone matrix 3. Osteoblasts secrete osteoid (a mix of gel and collagen fibers) 4. Calcium phosphate adds to the collagen, forming spongy bone. 5. Trapped osteoblasts become osteocytes. Copyright © 2010 Pearson Education, Inc. Figure 6.8, (2 of 4) Intramembranous ossification CT stem cells condensing to form the periosteum Spongy bone Blood vessel 6. Blood vessels arrive, and more spongy bone forms 7. Nearby connective tissue becomes the periosteum cover. Copyright © 2010 Pearson Education, Inc. Figure 6.8, (3 of 4) Intramembranous ossification Fibrous periosteum Osteoblast Plate of compact bone Spongy bone cavities contain red marrow 8. Osteoblasts change the way they lay down collagen, and form compact bone around the spongy bone, and below the periosteum. 9. Red marrow appears as blood cells are produced in the marrow cavities. Copyright © 2010 Pearson Education, Inc. Figure 6.8, (4 of 4) Month 3 Week 9 After conception Birth Articular cartilage Secondary ossification center Epiphyseal blood vessel Area of deteriorating cartilage matrix Hyaline cartilage Spongy bone formation Bone collar Primary ossification center 1 A hyaline cartilage “model” of a bone forms. Compact bone collar forms around it Copyright © 2010 Pearson Education, Inc. 2 Central cartilage area has a planned cell death Childhood to adolescence Spongy bone Epiphyseal plate cartilage Medullary cavity Blood vessel of periosteal bud 3 Blood vessels enter, ostepblasts and minerals arrive and spongy bone forms in diaphyses. 4 The diaphysis elongates and osteoclasts form the marrow cavity. In the epiphyses, cartilage dies and spongy bone forms. 5 The epiphyses ossify. Hyaline Cartilage remains only in the epiphyseal plates and articular cartilages. Figure 6.9 Growth in the length of long bones occurs at epiphyseal plate Resting zone Proliferation zone Cartilage cells undergo mitosis. 1 Hypertrophic zone Older cartilage cells enlarge. 2 Calcified cartilage spicule Osteoblast depositing bone matrix Osseous tissue (bone) covering cartilage spicules Copyright © 2010 Pearson Education, Inc. Calcification zone Matrix becomes calcified; cartilage cells die; matrix begins deteriorating. 3 4 Ossification zone New bone formation is occurring. Figure 6.10 Last Time We Covered… • Appositional Bone growth – Bone thickening/widening – Occurs when osteoblasts under the periosteum. produce bone faster than osteoclasts can absorb bone from the endosteal surface. • Bone grows/remodels in response to the forces placed on it. (Wolff’s Law) – Bones thickest at midpoint of diaphysis, bones thicker in dominant hand, thick prominences where muscles attach, weak bones in bed ridden people or astronauts. Load here (body weight) BONE SHAPE depends on the forces placed upon it Copyright © 2010 Pearson Education, Inc. Figure 6.13 What processes correct low blood calcium? 1. Falling blood Ca2+ levels 4. Calcium is released from bone into blood Thyroid gland 3. PTH stimulates osteoclasts to digest bone. Copyright © 2010 Pearson Education, Inc. Parathyroid glands 2. Parathyroid glands release parathyroid hormone into blood. PTH Figure 6.12 Last Time We Covered… • Fracture types: – – – – – – – – – – Nondisplaced/Displaced Complete/Incomplete Linear/Transverse Simple/Compound Comminuted Compression Spiral Epiphyseal Depressed Greenstick Hematoma Internal callus (fibrous tissue and cartilage) External callus New blood vessels Bony callus of spongy bone Healed fracture Spongy bone trabecula 1 A hematoma forms. 2 Fibrocartilaginous 3 Bony callus forms. callus forms. Copyright © 2010 Pearson Education, Inc. 4 Bone remodeling occurs. Figure 6.15 • Rickets: Last Time We Covered… – Vit. D or Calcium deficiency – Causes bone deformities because bone matrix is poorly mineralized: Soft bones called Osteomalacia – Rare in USA because of fortified milk • Osteoporosis: – Bone absorption outpaces bone formation – Porous weak bones. – Spine and femoral head most susceptible to fracture. Last Time… • The four characteristics of skeletal muscle: • 1. Excitable (turned on by nerves) • 2. Contractile (shorten when stimulated) • 3. Extensible (can elongate without damage) • 4. Elastic (can spring back to resting length) Copyright © 2010 Pearson Education, Inc. Skeletal Muscles are vascular • Each muscle is served by 1 artery, at least 1 vein, and 1 nerve M u S C L e Spinal cord EPImysium wraps whole muscle Tendon Each part of the muscle is wrapped in a connective tissue wrapping which protects the cells, and gives some stretch to the muscle (b) ENDOomysium (wraps individual muscle cells) PERImysium Wraps a bundle of muscle cells Fascicle: A bundle of muscle cells Muscle CELL (somethimes called a fiber) Figure 9.1 This is ONE muscle cell. What are the clues? MYOFIBRILS are broken into smaller units called SARCOMERES SARCOMERES are made of smaller units called FILAMENTS (myofilaments) Z disc Z disc (c) Small part of one myofibril enlarged to show the myofilaments responsible for the banding pattern. Each sarcomere extends from one Z disc to the next. Sarcomere Z disc Z disc Thin (actin) filament Elastic (titin) filaments Thick (myosin) filament (d) Enlargement of one sarcomere (sectioned lengthwise). Notice the myosin heads on the thick filaments. Figure 9.2c, d A single myosin molecule A place to bind to the actin in the thin filament A place for ATP to bind • Twisted double strand of G actin beads • G actin has active sites for myosin head attachment, but they are covered by tropomyosin • Tropomyosin and troponin: are proteins bound to actin that regulate whether or not the actin and myosin attach to each other and pull Last Time… • Sliding filament model • Step 1: Calcium is released from the SR and binds Troponin. • Step 2: Troponin changes shape and moves tropomyosin exposing binding site for myosin • Step 3: Myosin binds actin and ADP + Pi is released and power stroke occurs • Step 4: ATP binds to myosin and releases it from actin • Step 5: ATP hydrolyzed into ADP + Pi releasing energy and re-cocking myosin head • Step 6: Muscle contraction ends when calcium actively pumped back into SR Copyright © 2010 Pearson Education, Inc. WHY do the ions move the way they do? • Why does Ca+ move INTO the nerve cell? • Why does Na+ move INTO the muscle cell? • Why does K+ move OUT of the muscle cell? • HINT: you learned this in General Biology OUTSIDE IN Copyright © 2010 Pearson Education, Inc. Lo Na+ Lo ClLo Ca+ Hi K+ Hi Na+ Hi ClHi Ca+ Lo K+ IN Lo Na+ Lo ClLo Ca+ Hi K+ A nerve cell (brain or spinal cord must signal a muscle cell! Myelinated axon of motor neuron Axon terminal of neuromuscular junction Sarcolemma of the muscle fiber Action potential (AP) Nucleus 1 Action potential arrives at axon terminal of motor neuron. 2 Voltage-gated Ca2+ channels open and Ca2+ enters the axon terminal. Ca2+ Ca2+ Axon terminal of motor neuron 3 Ca2+ entry causes some Fusing synaptic vesicles synaptic vesicles to release their contents (acetylcholine) by exocytosis. ACh 4 Acetylcholine, a neurotransmitter, diffuses across the synaptic cleft and binds to receptors in the sarcolemma. Na+ K+ channels that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber. by its enzymatic breakdown in the synaptic cleft by acetylcholinesterase. Copyright © 2010 Pearson Education, Inc. Junctional folds of sarcolemma Sarcoplasm of muscle fiber 5 ACh binding opens ion 6 ACh effects are terminated Synaptic vesicle containing ACh Mitochondrion Synaptic cleft Ach– Degraded ACh Na+ Acetylcholinesterase K+ Postsynaptic membrane ion channel opens; ions pass causing a brief depolarization and repolarization. Postsynaptic membrane ion channel closed; ions cannot pass so no further depolarization occurs. Figure 9.8 The Action potential is a signal that moves along the sarcolemma and down the T tubules, and then Ca++ is released from the SR into the cytoplasm Steps in E-C Coupling: Voltage-sensitive tubule protein Sarcolemma T tubule Ca2+ release channel Terminal cisterna of SR Ca2+ Copyright © 2010 Pearson Education, Inc. Figure 9.11, step 3 Steps in E-C Coupling: Sarcolemma Voltage-sensitive tubule protein T tubule 1 Action potential is propagated along the sarcolemma and down the T tubules. Ca2+ release channel 2 Calcium ions are released. Terminal cisterna of SR Ca2+ Actin Troponin Ca2+ Tropomyosin blocking active sites Myosin 3 Calcium binds to troponin and removes the blocking action of tropomyosin. Active sites exposed and ready for myosin binding 4 Contraction begins Myosin cross bridge The aftermath Copyright © 2010 Pearson Education, Inc. Figure 9.11, step 8 Actin Ca2+ Myosin cross bridge Thin filament ADP Pi Thick filament Myosin 1 Cross bridge formation. Copyright © 2010 Pearson Education, Inc. Figure 9.12, step 1 ADP Pi 2 The power (working) stroke. Copyright © 2010 Pearson Education, Inc. Figure 9.12, step 3 ATP 3 Cross bridge detachment. Copyright © 2010 Pearson Education, Inc. Figure 9.12, step 4 ADP ATP Pi hydrolysis 4 Cocking of myosin head. Copyright © 2010 Pearson Education, Inc. Figure 9.12, step 5 Spatial summation Go to gym Large number of muscle fibers activated Large muscle cells Temporal summation Best sarcomere length High frequency of stimulation Muscle and sarcomere stretched to slightly over 100% of resting length FOUR WAYS TO INCREASE THE FORCE OF CONTRACTION Copyright © 2010 Pearson Education, Inc. Figure 9.21 What does TRYING HARDER mean?! Think harder (stimulate more brain cells) Turn on more nerves going to muscles Stimulus strength Maximal stimulus Threshold stimulus Proportion of motor units excited Strength of muscle contraction Turn on more muscle cells to create more FORCE Copyright © 2010 Pearson Education, Inc. Maximal contraction Figure 9.16 Very low frequency of stimulation leads to low force production Single stimulus SINGLE MUSCLE TWITCH Contraction Relaxation Stimulus A single stimulus is delivered. The muscle contracts and relaxes (muscle twitch) with low force Copyright © 2010 Pearson Education, Inc. Figure 9.15a Apply another stimulus before the first totally relaxes and the forces sum! Low stimulation frequency INCOMPLETE TETANUS Partial relaxation Stimuli The faster you stimulate the muscle, the more forcefully it contracts …………….UP TO A POINT…. Copyright © 2010 Pearson Education, Inc. Figure 9.15b Repeated fast stimulation makes the maximum force possible High stimulation frequency COMPLETE TETANUS Stimuli Probably because large amounts of calcium are entering the cell and allowing very rapid thin and thick filament pulling. Copyright © 2010 Pearson Education, Inc. Figure 9.15c 4. INCREASE FORCE by changing the sarcomere length Sarcomeres greatly shortened Sarcomeres at resting length Sarcomeres excessively stretched 75% 100% 170% Optimal sarcomere operating length (80%–120% of resting length) Copyright © 2010 Pearson Education, Inc. Figure 9.22 Does muscle contraction always produce movement? single cells and whole muscles always produces FORCE but Copyright © 2010 Pearson Education, Inc. shortens a muscle (isotonics) Or does NOT shorten a muscle(isometrics) (you TRY to move, and do) (you TRY to move, and don’t) Short-duration exercise STORED ATP ATP stored in muscles is used first. Copyright © 2010 Pearson Education, Inc. ENZYMES ATP is formed from creatine Phosphate and ADP using Enzymes in the cytoplasm GLYCOLYSIS Glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP using enzymes in the cytoplasm Prolonged-duration exercise AEROBIC METABOLISM ATP is generated by breakdown of several Nutrients in the mitochondria And requiring oxygen. Figure 9.20 (a) Direct phosphorylation Coupled reaction of creatine phosphate (CP) and ADP Energy source: CP CP ADP Creatine kinase Creatine ATP Fuels: CP, ADP Produces: 1 ATP per CP Provides ATP for 15 seconds of Activity. Oxygen use: None Products: 1 ATP per CP, creatine Duration of energy provision: 15 seconds Copyright © 2010 Pearson Education, Inc. Figure 9.19a (b) Anaerobic pathway Glycolysis and lactic acid formation Energy source: glucose Produces: a. 2ATP per glucose and b. Lactic acid-diffuses into Glucose (from glycogen breakdown or delivered from blood) the bloodstream and is used as fuel by the liver, kidneys, and heart, OR converted back into pyruvic acid by the liver. Glycolysis in cytosol 2 O2 ATP Fuel: glucose Pyruvic acid Provides ATP for 60 seconds of activity. net gain O2 Released to blood Lactic acid Oxygen use: None Products: 2 ATP per glucose, lactic acid Duration of energy provision: 60 seconds, or slightly more Copyright © 2010 Pearson Education, Inc. Figure 9.19b (c) Aerobic pathway Aerobic cellular respiration Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism Fuels: glycogen, glucose, Fatty acids, amino acids Needs: Oxygen & Mitochondria!!! Produces: 32 ATP per glucose Glucose (from glycogen breakdown or delivered from blood) O2 Pyruvic acid Fatty acids O2 Aerobic respiration Aerobic respiration in mitochondria mitochondria Amino acids 32 CO2 H2O ATP Produces 95% of ATP during rest and light to moderate exercise. BUT, if you go too fast, ATP production cannot keep up, and you FATIGUE. net gain per glucose Oxygen use: Required Products: 32 ATP per glucose, CO2, H2O Duration of energy provision: Hours Copyright © 2010 Pearson Education, Inc. Figure 9.19c So, if you want to run for a long time you need the right resources…… You get them by aerobic (endurance) training: -Makes chest muscles stronger to pull in more oxygen -encourages capillary growth to bring oxygen to muscles -increases myoglobin synthesis so cells hold more oxygen -increases the number of mitochondria in cells, to make more ATP Capillaries grow at about the same rate as grass. Copyright © 2010 Pearson Education, Inc. Light colored cells are called FAST TWITCH MUSCLE CELLS They have: • Few myoglobin ((oxygen holding molecule) • Few mitochondria • Higher glycogen stores • Fast speed of contraction Based on their characteristics are these aerobic or anaerobic cells? Hint: think of how much ATP the above ingredients could produce… Copyright © 2010 Pearson Education, Inc. Dark colored muscle cells are called SLOW TWITCH MUSCLE CELLS They have: • Lots of myoglobin (oxygen holding molecule) • Many mitochondria • Lower glycogen stores • SLOW speed of contraction Based on their characteristics are they aerobic or anaerobic cells? Hint: think of how much ATP the above ingredients could produce… Copyright © 2010 Pearson Education, Inc. Strategies for doing well on the test: • Read the test first, make sure you understand what is expected of you. • Manage your time! If you get stuck on a MC question, skip it and come back later. • Multiple Choice/Matching questions: • Your first instinct is usually correct. • If you get stuck, try and eliminate at least two responses you know are incorrect. That way you now have a 50/50 chance, and remember your first instinct. • You can also read the question before each response, this can help you to weed out answers if they don’t sound right. • Read the question CAREFULLY, make sure you know what it is asking before selecting an answer. Copyright © 2010 Pearson Education, Inc. Strategies for doing well on the test: • Written questions: • Decide which questions you are going to answer at the beginning. • Make an outline of the points you want to cover. • Pay attention to information in MC questions that may help you answer written questions. • Use your outline to construct your response into sentences that tell a story. • Re-read your answers as you go and make sure you are answering the questions asked. • If you are not sure of something, raise your hand or come up and ask! Copyright © 2010 Pearson Education, Inc.