Exam Review – Ch 1

Exam Review – Ch 1 - Structure and Function...

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Unformatted text preview: Structure and Function of Muscular, Nervous & Skeletal Systems Muscular System There are 3 types of muscle tissue: Cardiac muscle o Composes the walls of the heart o Involuntary muscle, therefore is not subject to conscious control Smooth muscle o Lines the internal organs (intestines & stomach) o Involuntary Skeletal muscle o Attaches to the skeleton via tendons to produce bodily movement Functions of Skeletal Muscle Locomotion o Produce movement Muscle pulls tendons to move the skeleton Body posture o Maintain posture and body position Continuous muscle contraction Venous return o Support soft tissue Support weight of visceral organs o Guard entrances and exits Encircle openings to digestive and urinary tracts. Control swallowing, defecation and urination Thermogenesis o Maintain body temperature Energy from contraction is converted to heat Anatomy of Skeletal Muscle (Blood Vessels and Nerves) Muscle contractions require energy Blood vessels deliver oxygen and nutrients to produce ATP Muscle contractions are under stimulation from the CNS Voluntary control Axons connect to individual muscle fibers Myofibrils- Cylinder as long as entire muscle fiber- Each fiber contains 100s to 1000s - Responsible for contraction- When myofibrils contract the whole cell contracts- Consist of proteins Actin: thin filaments Myosin: thick filaments Sarcoplasmic Reticulum- Specialized form of ER- Tubular network around each myofibril- In contact with T-Tubule- Cisternae expanded chambers of SR, store Calcium Sacromere- Smallest functional unit of muscle fiber- Each myofibril contains 10,000 sarcomeres end to end- Interaction between thick and thin filaments cause contraction- Banded appearance Thick and Think Filaments Thin (myosin) twisted actin molecules Each has an active site where they interact with myosin Resting active site covered by tropomyosin which is held in place by troponin Thick (actin, troponin, tropomyosin) Myosin Head attaches to actin during contraction Can only happen if troponin changes position, moving tropomyosin to expose active site Contraction of a Muscle Fiber Sliding-Filament Theory 1) Force of contraction is generated by the process that slides the actin filament over the myosin filament o note: myosin cross-bridges are always attached to actin 2) The length of the thick and thin filaments do not change 3) The length of the sarcomere decreases as actin is pulled over the myosin Sliding Filaments and Cross Bridges Sarcomere contraction Sliding Filament Theory Thin filaments slide toward center of sarcomere...
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Exam Review – Ch 1 - Structure and Function...

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