1. Muscle & Muscle Tissue

2. Types of Muscle Tissue Skeletal Are striated Controlled voluntarily Tires easily

3. Types of Muscle cont. Smooth Walls of visceral organs Force fluids through internal channels Not voluntary Not striated

4. Cardiac Found only in the heart Striated Not voluntary

5. Muscle structure Made up of 4 connective tissue Epimysium Fascicle Perimysium Endomysium

6. Gross Anatomy of a Skeletal Muscle Epimysium Outermost layer Connective tissue surrounding the entire muscle tapers at end to form tendon

7. Fascicle Inside the muscle are discrete areas of muscle tissue

8. Perimysium Connective tissue surrounding each fascicle

9. Endomysium Thin connective tissue surrounding each muscle fiber (cell) Smallest unit of muscle visible without a microscope

10. Skeletal Muscle Muscles always contract actively Can extend only passively Ability to move a bone part in opposite directions requires that muscles be attached to the skeleton Tire easily Bundle of long fibers running the length of the muscle Each fiber is a single cell with many nuclei & consists of bundles of smaller myofibrils arranged longitudinally

11. Muscle Fiber Single muscle cell Cylindrical in structure Surrounded by membrane capable of excitation & impulse propagation Contains muscle fiber bundles called myofibrils

12. Sarcolemma Delicate sheath (cell membrane) Made up of lipid molecules Transport nutrients & synthesizes proteins Sodium/potassium pump Maintain shape of muscle cell

13. Sarcoplasm Aqueous substance – cytoplasm Surrounds myofibrils House the mitochondria Houses blood vessels, glycogen & nerve endings

14. Myofibrils Fibers functional unit Threadlike structure within muscle fiber Contains sarcomeres at intervals Made up of 2 protein fibers – microfilaments

15. Sarcoplasmic Reticulum Specialized endoplasmic reticulum Function is to store calcium and release it on demand when a muscle fiber is stimulated to contract Initiates muscle contraction at the sarcomere

16. Sarcomere Segment of myofibril Composed of 2 contractile proteins Actin Myosin Sarcomeres are separated by Z lines

17. Sarcomere Has a dark band – A band The A band has light zone called the H band (this disappears when contracted) Center of the H band is the M line

18. Sarcomere I band contains Actin Length varies with the start of muscle contraction

19. Myofilaments Protein fibers Composed of 2 filaments Actin – thin Myosin - thick Divided into bands which alternate light and dark

20. Thick filaments A bands are dark areas Dark areas represent thick filaments 2 thick filament dark areas are connected by the M line Consist of myosin & ATPase Enzyme splits ATP to generate the power of muscle contractions

21. Thin filaments I band Light areas contain thin filaments Made up of actin, troponin and tropomyosin