Larry M. Frolich, Ph.D. Biology Department, Yavapai College Movement—muscle and bone Muscle structure and contraction Movement across joints Bones
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Movement—muscle and bone Muscle structure and contraction Movement across joints Bones
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Overview Neuron brings impulse to synapse with muscle Muscle cells shorten by sliding protein filaments (actin- myosin units) Great in-depth molecular understanding of how muscle moves Movements at protein level cause whole muscle to rapidly shorten or contract
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Muscle cell structure Muscle cells are large—visible with naked eye as “fibers of meat/chicken/fish Each cell contains hundreds of myofibrils Each myofibril contains actin/myosin filamentous proteins all lined up (gives striated appearance in microscope)
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Parts of muscle cell Sarcolemma—muscle cell membrane (“excitable” membrane like neuron can generate action potential) Sarcoplasmic reticulum—endoplasmic reticulum in muscle (holds Ca +2 ions) T-tubules penetrate into cell and contact sarcoplasmic reticulum
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Calcium release in muscle Motor neuron impulse arrives to axonal terminus Neuro-muscular junction synapse passes message on to muscle cell Sarcolemma (muscle cell membrane) undergoes action potential all along length of cell membrane and into T-tubule system Voltage change causes release of Ca +2 ions into muscle cell Calcium causes actin-myosin units (sarcomeres) to shorten
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Sliding filament model Thick filaments (myosin) “row” or pull in thin filaments (actin) Molecular cross- bridges undergo cycling shape change in the presence of calcium
Larry M. Frolich, Ph.D. Biology Department, Yavapai College
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Muscle contraction requires energy Three sources of energy, all part of cellular respiration
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Muscle cells all lined up in skeletal muscle Contaction of many cells makes whole muscle shorten bringing about body movements Movement happens across joints between skeletal elements Shortening of actin-myosin units lead to whole muscle contraction
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Movement—muscle and bone Muscle structure and contraction Movement across joints Bones
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Joints Joints connect skeletal elements Synovial joints are lubricated, mobile joints Skeletal elements linked by synovial joints move when muscles pull on those skeletal elements This is how movement happens
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Technical vocabulary for movement across joints—very specific
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Movement—muscle and bone Muscle structure and contraction Movement across joints Bones
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Structure of a bone Bone is alive Has nerves, blood supply, cells Connective tissue very organized in layers around blood vessels Cells make bone tissue, dissolve bone tissue, live inside bone tissue
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Fetal bone formation Cartilage model forms first Then bony tissue fills in around blood vessels Final bone has three parts: central shaft (diaphysis) and two ends (epiphyses)
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Growth plate New bone tissue forms within cartilage Bone growth occurs at cartilaginous growth plate between diaphysis and epiphysis at either end of bone
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Inside of diaphysis is hollow tube called medullary cavity In life filled with bone marrow, where blood cells form Diameter of bone grows by bone formation around outside and bone absorption on inside Medullary cavity
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Calcium regulation and bone Bone also serves as calcium storage Calcium is needed for many aspects of cell metabolism, but especially in muscle cells Calcium regulation is negative feedback mechanism Release of calcium by degrading bone can be contrary to support role of bone
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Osteoporosis is result of calcium need outweighing bone support role Affects elderly, especially women Bone resorption proceeds faster than deposition Low estrogen levels implicated but estrogen replacement now considered risky Importance of calcium in diet??? Leads to fractures –Compression fractures of vertebrae –Neck of femur Lifelong habit of weight-bearing activity is probably best remedy
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Total Movement Picture Neurons trigger muscle to contract based on stimuli or sensory input Muscle contracts by sliding filaments Muscle pulls on bone to cause movement across joint
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Movement—muscle and bone: Review Muscle structure and contraction Movement across joints Bones
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Overview Neuron brings impulse to synapse with muscle Muscle cells shorten by sliding protein filaments (actin- myosin units) Great in-depth molecular understanding of how muscle moves Movements at protein level cause whole muscle to rapidly shorten or contract
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Muscle cell structure Muscle cells are large—visible with naked eye as “fibers of meat/chicken/fish Each cell contains hundreds of myofibrils Each myofibril contains actin/myosin filamentous proteins all lined up (gives striated appearance in microscope)
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Sliding filament model Thick filaments (myosin) “row” or pull in thin filaments (actin) Molecular cross- bridges undergo cycling shape change in the presence of calcium
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Muscle cells all lined up in skeletal muscle Contaction of many cells makes whole muscle shorten bringing about body movements Movement happens across joints between skeletal elements Shortening of actin-myosin units lead to whole muscle contraction
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Joints Joints connect skeletal elements Synovial joints are lubricated, mobile joints Skeletal elements linked by synovial joints move when muscles pull on those skeletal elements This is how movement happens
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Structure of a bone Bone is alive Has nerves, blood supply, cells Connective tissue very organized in layers around blood vessels Cells make bone tissue, dissolve bone tissue, live inside bone tissue
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Calcium regulation and bone Bone also serves as calcium storage Calcium is needed for many aspects of cell metabolism, but especially in muscle cells Calcium regulation is negative feedback mechanism Release of calcium by degrading bone can be contrary to support role of bone
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Osteoporosis is result of calcium need outweighing bone support role Affects elderly, especially women Bone resorption proceeds faster than deposition Low estrogen levels implicated but estrogen replacement now considered risky Importance of calcium in diet??? Leads to fractures –Compression fractures of vertebrae –Neck of femur Lifelong habit of weight-bearing activity is probably best remedy
Larry M. Frolich, Ph.D. Biology Department, Yavapai College Total Movement Picture Neurons trigger muscle to contract based on stimuli or sensory input Muscle contracts by sliding filaments Muscle pulls on bone to cause movement across joint