The Anatomy of Skeletal Muscle Muscle fiber looking outward: Perimysium ______________________ Epimysium ____________________ Muscle fiber looking inward: Endomysium _______________________________ ______________ _______________ Contains cytoplasm (sarcoplasm) _____________ Contain actin and myosin Contains myosin and actin Muscle fibre Perimysium Epimysium Endomysium Muscle belly Tendon ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook.
Properties of Muscle Fiber Contractibility Refers to muscle shortening in length Elasticity Refers to muscle stretching and returning to normal position Extensibility ___________________________________ Conductivity ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook.
_____________________ Axon Neurotransmitter acetylcholine (Ach) Sarcolemma Axon Terminal Synaptic Cleft Receptor ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook.
Structure of Skeletal muscles The myofibril consists of protein chains called ________________ Myofilaments have a symmetrical, alternating pattern of thick and thin elements.
Skeletal Muscle Myosin _____________________ consists of a large number of bundled myosin molecules aligned in overlapping arrays.
Skeletal Muscle Actin __________________________ made up of two helically intertwined chains of G-actin (globular actin) units. Other proteins that bind to the actin molecules: _________________ The Troponin complex→ made up of three members
The Steps of Muscle Contraction: The Sliding Filament Theory
Key events that must take place before the contraction of a muscle fiber begins: _______________________________________ _______________________________________ The calcium ions ____________________which causes the troponin-tropomyosin complexes to move away from the myosin binding sites on actin. Once this happens contraction can begin. The process is similar to rowing, each myosin head rows forward using the actin as a base to pull from.
Step 1: ATP hydrolysis by Myosin __________________________________ __________________________________ ATP is hydrolyzed into ADP freeing up a Phosphate molecule, this energizes the myosin head.
Step 2: Myosin Attaches to Actin Myosin attaches to the myosin binding site on actin and releases the free phosphate group __________________ __________________ __________________
Step 3: The Powerstroke Phosphate release by myosin triggers the actual power contraction stroke _________________________________ Myosin head rotates and _____________ As the head rotates it moves in a ratchet like motion and pulls the thin filaments closer to the center of the M line of the sarcomere
Step 4: Detachment of Myosin When the ratchet motion is over the myosin awaits another ATP so it can be released from the actin binding site __________________________________ __________________________________ If not the Myosin remains locked in place and the muscle remains locked up as well this is called “__________”
END RESULTS FOR SARCOMERE Z lines move closer together ________________ I band shortens ___________________ A band stays the same
Summary Points ________________________________ The movement of myosin and actin is like rowers moving across water Myosin heads will keep binding with actin sites until the ATP runs out or the Calcium levels decrease __________________________________ __________________________________
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