IPHY 3410 1st Edition Lecture 7 Outline of Last Lecture 1 Distinguish between axial skeleton and appendicular skeleton 2 Identify the specific locations of cartilages in the adult body 3 Explain the functions of cartilage 4 Explain the functional properties of cartilage itself 5 Identify the unique characteristics and locations of hyaline fibro and elastic cartilages 6 Compare the three kinds of cartilage in terms of structure function and location 7 Explain why bones are considered organs Discuss the tissues comprising a bone 8 List and explain the main functions of the bony skeleton 9 Classify bones according to shape include several examples for each category 10 Describe the gross anatomy of a typical long bone 11 Describe where compact and spongy bones are located in a long bone 12 Differentiate the histology of compact and spongy bone 13 Explain why Prof Kram dislikes the term spongy bone 14 Explain why spongy bone and compact bones are found where they are in a long bone 15 Describe the structure function and relationship among central canal perforating canal lamellae lacuna and canaliculi Outline of Current Lecture Skeletal Muscle 1 Describe the functions characteristics of muscle tissue that distinguish it from other types of tissues 2 Name the layers of connective tissue that occur in and around a skeletal muscle 3 Describe and explain the structural and organizational levels of skeletal muscle Begin with the muscle as an organ followed by the fascicle muscle fiber myofibril and sarcomere then end with the myofilament 4 List general characteristics of skeletal muscle fibers 5 Explain the sliding filament theory in the simplest form 6 Describe the role of titin in the sarcomere Current Lecture Muscle Function of muscle tissue Muscle tissues generate force in response to a stimulus from the nervous system in order to o Move material through the body o Move slow or stabilize parts of the body and produce overall movement ex locomotion o To generate heat intentional or not Properties of Muscle Tissue Excitability muscle cell responds to a neural electrical stimulus Contractility in response to stimulus muscle cells generate tension force and contracts or resists lengthening Extensibility when excitation ends muscle cells can be easily stretched back to resting length Elasticity muscle cells can be stretched beyond its resting length and then it passively shortens back to resting length like a spring Note muscle cells only exert pulling forces they cannot push But pulling forces can resist lengthening 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 Types of Muscle Tissue Skeletal muscle o Moves the skeleton o Approximately 40 of body weight o Under voluntary control o Striated Cardiac muscle o Only found in heart wall o Under involuntary control o Striated Smooth muscle o In walls of most internal organs and bloods vessels o Under involuntary control o Note 1 muscle cell 1 muscle fiber Structures found in all 3 muscle types Muscle fiber a muscle cell Sarcolemma plasma membrane Sarcoplasm cytoplasm of a muscle cell Myofilaments cytoskeletal unit o Thin actin filaments o Thick myosin filaments Myofibrils rodlike bundles of actin myosin that run parallel within a muscle cell fiber T tubule extension of sarcolemma into cell wraps around myofibrils carry electrical stimulus into cell Sarcoplasmic Reticulum modified endoplasmic reticulum that stores and pumps calcium ions o Calcium triggers force generation Skeletal Muscle An Overview Attach to bone directly or via tendon Some attach to skin 1 muscle fiber cell can be the length of entire muscle not usually Can range in length from 1 cm to 30 cm Long cylindrical multinucleated cells fibers Connective Tissue Found in Skeletal Muscle Endomysium loose CT surrounding a single muscle fiber Perimysium dense CT surrounding a muscle fascicle o Fasicle collection of muscle fibers Epimysium dense irregular CT surrounding a muscle Veins Arteries and Nerves Veins remove cellular waste Arteries provide oxygen nutrients Nerves innervate muscle cells Microscopic Anatomy of a Skeletal Fiber Structure of a myofibril o Sarcomere functional units within a myofibril repeat the entire length of each myofibril organization w in each sarcomere gives muscle a striated appearance o Myofilaments actin myosin o Z disc protein disc joining adjacent sarcomeres Each sarcomere shortens a little bit the result adding to the total shortening of the myofibral o A band primarily myosin thick filaments Always stays the same length o I band primarily actin thin filaments Titin huge spring like protein that attaches z disc to myosin Contraction of a Skeletal Muscle During a contraction actin myosin filaments slide row past one another o Sliding Filament Theory myosin heads attach to actin in the thin filaments then pivot to pull the thin filaments inward Helpful Videos MUSCLE ORGANIZATION SLIDING FILAMENT THEORY http www youtube com watch v EdHzKYDxrKc MUSCLE CONTRACTION http www youtube com watch v XoP1diaXVCI SARCOMERE CONTRACTION http www youtube com watch v J9K1enGBJRw