Muscles and Movement AHL IB Biology

STARTER– Watch the video below and answer the questions Which muscles is he using to keep the rock off his body? What muscle on his chest is the rock resting on? Which muscles contracted to allow him to throw the rock off his body?

Learning objectives State the roles of bones, ligaments, muscles, tendons and nerves in human movement. Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps). Outline the functions of the structures in the human elbow joint Compare the movements of the hip joint and the knee joint. Describe the structure of striated muscle fibres, including the myofibrils with 2 lightand dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.

Learning Objectives Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands. 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 use of ATP to break cross-bridges and re-set myosin heads. Analyse electron micrographs to find the state of contraction of muscle fibres.

Sliding filament theory As you watch the video – can you put the statements on your handout into order? (place the correct number in the space provided)

Answers 3 5 2 4 1

Now complete your Sliding Filament Theory cut and paste exercise Cut out all the boxes and then paste them down on the empty page in your workbook. Once you have finished, try completing the flow chart in your workbook

Group thought: How does the sarcomere change during contraction?

(a)Identify the structures labelled I and II on the diagram of the elbow joint below. (2) (b)Explain how the action of the muscles is co-ordinated at this joint by the nervous system. (3)

I.humerus II.synovial fluid / membrane / capsule 2 muscles are co-ordinated by reflexes from the CNS / spinal cord; the biceps and triceps muscles are antagonistic; contraction of a muscle is stimulated by motor nerves; stretch receptors / proprioreceptors in muscles and tendons sense muscle stretching; when stretch receptors in muscles are stimulated they produce a reflex stimulating muscle contraction / stretch reflex; reciprocal innervation of muscles / when one muscle is excited the antagonistic muscle receives no excitation / is inhibited; 3 max