CAS Biology 11.2 Muscles and Movement
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The document discusses the structure and function of muscles and sarcomeres. It describes how muscles are made up of sarcomeres, which contain thick myosin filaments and thin actin filaments. Sarcomeres shorten during muscle contraction as the actin and myosin filaments slide past each other through a cross bridge cycle of formation, power stroke, detachment and reactivation of the myosin head. This causes the A band width to remain the same and the H zone and I bands to decrease in size.
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CAS Biology 11.2 Muscles and Movement
- 1. 11.2 MUSCLES & MOVEMENT IB BIOLOGY
- 2. MOVEMENT: THE HUMAN MACHINE • Joints • Bones • Nerves • Muscles • Tendons • Ligaments
- 4. THE ELBOW
- 5. THE ELBOW • Biceps – bends the arm (flexor) • Triceps – straightens the arm (extensor) • Humerus – anchors muscle (muscle origin) • Radius/Ulna – acts as forearm levers (muscle insertion) • Radius acts as a lever for the biceps • Ulna acts as a lever for the triceps • Cartilage – allows easy movement (smooth surface), absorbs shock and distributes load • Synovial fluid – provides food, oxygen, and lubrication to the cartilage • Joint capsule – seals the joint space and provides passive stability by limiting range of movement
- 6. KNEE JOINT VS HIP JOINT
- 7. KNEE JOINT VS HIP JOINT Similarities: - Both are synovial joints - Both are involved in the movement of the leg Differences:
- 8. MUSCLE STRUCTURE sarcomeres < myofibrils < muscle fibers = MUSCLES muscle fibers – long multinucleate cells Within each muscle fiber are cylindrical structures called myofibrils Myofibrils consist of repeating units called sarcomeres, which have light and dark bands
- 10. STRIATED MUSCLE FIBER Sarcolemma – specialized plasma membrane Sarcoplasmic reticulum – specialized endoplasmic reticulum designed for muscle contraction (contains high Ca2+) Myofibrils – tubular fibers divided into sections called sarcomeres, and made up of two different myofilaments (actin & myosin) Mitochondria – large numbers in order to produce enough ATP for muscle contraction
- 12. SARCOMERES
- 13. SARCOMERES
- 14. SARCOMERES H zone – area only occupied by the thick filaments (myosin) I bands (light) – regions occupied by only thin filaments (actin) A bands (dark) - are the region occupied by both filaments (overlap) Z lines – represent the extremeties of a single sarcomere
- 15. SARCOMERES H zone – area only occupied by the thick filaments (myosin) I bands (light) – regions occupied by only thin filaments (actin) A bands (dark) - are the region occupied by both filaments (overlap) Z lines – represent the extremeties of a single sarcomere
- 17. SARCOMERES H-zone I band A band I band
- 20. SARCOMERE CONTRACTION What do you expect to happen to the: H zone? A band? I band?
- 23. SARCOMERE CONTRACTION Four Stages of Cross Bridge Cycle 1) Cross Bridge Formation 2) Power Stroke 3) Cross Bridge Detachment 4) Reactivation of Myosin Head