Locomotion and Movement

Movement is a significant feature of living beings, and movements that result in a change of place are called locomotion. This chapter describes three types of movement in human cells: amoeboid movement in macrophages and leucocytes, ciliary movement in the trachea and fallopian tubes, and muscular movement. You will study skeletal, visceral and cardiac muscle, and the structure of a skeletal muscle fibre with its sarcolemma, sarcoplasmic reticulum and myofibrils. The repeating sarcomere lies between two Z lines, with dark A bands of myosin and light I bands of actin, which carries troponin and tropomyosin. The sliding filament theory explains how a nerve signal releases acetylcholine at the neuromuscular junction and calcium from the sarcoplasmic reticulum, so that myosin heads form cross-bridges and use ATP to pull actin filaments towards the centre of the sarcomere. The chapter then describes the human skeleton of 206 bones, 80 axial and 126 appendicular, the girdles, the types of joints (fibrous, cartilaginous and synovial) and disorders such as myasthenia gravis, muscular dystrophy, tetany, arthritis, osteoporosis and gout.

Detailed Worksheet: Locomotion and Movement Section A - Definitions (10 marks) 1. Distinguish between red and white muscle fibres. (2 marks) 2. What is a sarcomere? (2 marks) 3. What are true ribs, false ribs and floating ribs? (2 marks) 4. What is a synovial joint? Give two examples. (2 marks) 5. What is myasthenia gravis? (2 marks) Section B - Calculations and Applications (15 marks) 6. A sarcomere at rest is 2.4 micrometres long with A bands 1.6 micrometres long. Calculate the total length of the I band within the sarcomere. During contraction the sarcomere shortens to 2.0 micrometres. Which band changes length, and what happens to the A band? (3 marks) 7. The human skull has 29 bones: 8 cranial, 14 facial, 1 hyoid and the ear ossicles. Calculate the number of ear ossicles and the number in each ear. Name the ear ossicles. (3 marks) 8. Count the bones of one human forelimb: humerus, radius, ulna, carpals, metacarpals and phalanges. Calculate the total for both forelimbs. Similarly, calculate the bones in one hindlimb including the patella. (3 marks) 9. The vertebral column has 26 vertebrae. Given 7 cervical, 12 thoracic and 5 lumbar vertebrae, calculate the remaining number and name them. Why is the number of cervical vertebrae the same in almost all mammals? (3 marks) 10. A muscle fibre uses ATP at a rate of 100 molecules per myosin head per second (illustrative). If a myofibril contains 5,000 myosin heads, calculate the ATP used in 3 seconds. Why does a muscle fatigue during prolonged exercise? (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of a sarcomere showing the A band, I band, H zone, M line and Z lines. (4 marks) 12. Draw labelled diagrams of the actin and myosin filaments. (3 marks) 13. Draw a labelled diagram of the human pectoral and pelvic girdles. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Explain the sliding filament theory of muscle contraction. What are the roles of calcium ions and ATP? (5 marks) 15. Classify the joints of the human body with examples. How does a synovial joint allow free movement? (5 marks) 16. Explain the causes and effects of muscle fatigue, osteoporosis, arthritis and gout. Suggest ways to keep the musculoskeletal system healthy. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams neatly with labels. Show the steps of calculations.