b.1.1 state the roles of bones, ligaments, muscles, tendons, and nerves in the human movement
Bones provide a firm anchorage for muscles. They also act as levers, changing the size or direction of forces generated by muscles. Ligaments connect bone to bone, restricting movement at joints and helping to prevent dislocation. Tendons attach muscles to bone. Nerves stimulate muscles to contract at a precisetime and extent, so that movement is co-ordinated.
b.1.2 label a diagram of the human elbow joint. Including cartilage, synovial fluid, joint capsule, name bones and atagonistic muscles (biceps and triceps)
See attached
b.1.3 Outline the functions of the structures in the human elbow joint.
Biceps are the flexor muscle used to bend the arm at the elbow. The humerus bone provides a firm anchorage for the muscle. Triceps are the extensor muscles, used to straighten the arm. Capsule seals the joint. The synovial fluid lubricates the joint to reduce friction. The tendons attach muscle to bone. The radius is the bone that transimts forces from the biceps through the forearm. The ulna is the bone that transmits forces from the triceps to the forearm. Cartilage is a layer of smooth and tough tissue that covers the ends of the bones where they meet to reduce friction.
b. 1.4 compare the movements of the hip and knee joint
The knee joints are hinge joints, and are formed by the meeting of the femur and the tibia in the lower leg. The quadriceps causees knee extension and there are several muscles involved in bending the leg. The hip joint is a ball and socket kind of joint. The “ball” is the rounded surface of a joint that moves inside another bone. This kind of joint moves more freely than hinge joints.
b.1.5 describe the structure of striated muscle fibers, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma
When viewed with a light microscope skeletal muscle is seen to consist of large multinucleate cells called muscle fibers. Within each muscle fiber are cylindrical structures called myofibrils. The myofibrils consist of repeating units called sarcomeres, which have light and dark bands. The light and dark bands extend across all the myofibrils in a muscle fiber, giving it a striated (striped) appearance. Around each myrofibril is a special type of endoplasmic reticulum, called sarcoplasmic reticulum, visible in the electron micrograph. There are also mitochondria between the myofibrils.
b.1.6 draw and label a diagram to show the structure of a sacromere, uncluding z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands
b.1.7 explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross bridges, the sliding of actin and myosin filaments, and the sue of ATP to break cross bridgesand reset myosin heads
1. The myosin filaments have heads wich form cross-bridges when they are attached to binding stes on acting filaments. 2- ATP binds to the myosin heads and causes them to break the crossbridges by detaching from the binding sites. 3- ATP is hydrolysed to ADP and phosphate, causing they myosin heads to change their angle. The heads are said to be “cocked” in their new position as they are storing potential energy from ATP. The heads attach to binding sites on actin that are further from the center of the sarcomere than the previous sites.
b.1.8 analyze electron micrographs to find the state of contraction of muscle fibers.
The contracted muscles are on the left, in the picture provided on page 100 of the IB biology book.
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