Skeleton and Movement
Year 8 ๐ซ Physiology & Health Bones, joints, muscles, and antagonistic muscle pairs.
๐ The Skeleton
The skeleton provides support, protection, movement, and produces blood cells.
- Support โ maintains body shape
- Protection โ skull (brain), ribcage (heart + lungs), vertebral column (spinal cord)
- Movement โ bones act as levers; joints allow movement
- Blood cell production โ red and white blood cells made in red bone marrow
- Mineral storage โ calcium and phosphorus stored in bone
๐ฆด Joints and Movement
| Joint type | Movement allowed | Example |
|---|---|---|
| Ball-and-socket | All directions (most range) | Hip, shoulder |
| Hinge | One plane only (like a door hinge) | Knee, elbow |
| Pivot | Rotation | Atlas/axis (neck) |
| Fixed (sutured) | No movement | Skull plates |
Antagonistic Muscle Pairs
Muscles can only PULL (contract) โ they cannot push. Pairs work in opposition: when biceps contracts โ arm bends; when triceps contracts โ arm straightens.- Tendons โ connect muscle to bone (inelastic)
- Ligaments โ connect bone to bone at joints (slightly elastic)
- Cartilage โ smooth surface at bone ends; cushions joint
- Synovial fluid โ lubricates joint; reduces friction
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