PE1: The Skeletal System
Bones of the body, axial vs appendicular skeleton, functions and classifications of bones.
🦴 Overview of the Skeleton
Key Fact: The adult human skeleton is made up of 206 bones. At birth, humans have around 270 bones, but many fuse together as the body grows.
The skeleton serves as the body's internal framework, providing structure, protection and enabling movement. It is divided into two main groups:
- Axial skeleton - 80 bones forming the central axis of the body
- Appendicular skeleton - 126 bones forming the appendages (limbs) and their attachments
🧍 Axial vs Appendicular Skeleton
| Feature | Axial Skeleton | Appendicular Skeleton |
|---|---|---|
| Number of bones | 80 | 126 |
| Location | Central axis of the body | Limbs and limb attachments |
| Key bones | Skull, vertebral column, ribcage, sternum | Arms, legs, pectoral girdle, pelvic girdle |
| Primary function | Protection of vital organs, support of upright posture | Movement and locomotion |
| Examples | Cranium (8 bones), vertebrae (33), ribs (24), sternum (1) | Humerus, radius, ulna, femur, tibia, fibula, scapula, clavicle, pelvis |
Exam Tip: The pectoral girdle (shoulder) and pelvic girdle (hip) are part of the appendicular skeleton, not the axial. A common mistake is thinking the pelvis belongs to the axial skeleton because it's in the centre of the body.
⚡ Five Functions of the Skeleton
You must know all five functions: Support, Protection, Movement, Mineral Storage, Blood Cell Production.
1. Support
The skeleton provides a rigid framework that supports the body against gravity and gives the body its shape. Without the skeleton, the body would collapse. Muscles attach to bones via tendons, and bones act as levers for movement.
- The vertebral column supports the weight of the head and torso
- The legs support the entire body weight when standing
- The ribcage supports the chest area and maintains its shape
2. Protection
Bones protect vital internal organs from damage. This is crucial for survival during physical activity and contact sports.
- The cranium protects the brain
- The ribcage protects the heart and lungs
- The vertebral column protects the spinal cord
- The pelvis protects the reproductive organs and bladder
3. Movement
Bones act as levers that muscles pull on to create movement at joints. Different joints allow different ranges of movement.
- The femur acts as a lever for running and kicking
- The humerus acts as a lever for throwing and striking
- Vertebrae allow the spine to flex and rotate
4. Mineral Storage
Bones store essential minerals, particularly calcium and phosphorus. These minerals can be released into the bloodstream when needed by the body.
- Calcium is needed for muscle contraction, blood clotting and nerve impulse transmission
- Phosphorus is needed for energy transfer (ATP) and bone formation
- Up to 99% of the body's calcium is stored in bones and teeth
5. Blood Cell Production
Red bone marrow found in certain bones produces blood cells. This process is called haematopoiesis.
- Red blood cells (erythrocytes) - carry oxygen
- White blood cells (leucocytes) - fight infection
- Platelets (thrombocytes) - help blood clot
- Red marrow is found in the sternum, ribs, pelvis, vertebrae and ends of long bones
📐 Classification of Bones
Bones are classified by their shape, which relates to their function:
| Bone Type | Description | Function | Examples |
|---|---|---|---|
| Long | Longer than they are wide; shaft with two ends | Act as levers for movement; contain red marrow in ends | Femur, humerus, tibia, fibula, radius, ulna, phalanges |
| Short | Roughly cube-shaped; spongy inside | Provide stability and some movement; absorb shock | Carpals (wrist), tarsals (ankle) |
| Flat | Thin, flattened and often curved | Protection of organs; large area for muscle attachment | Cranium, scapula, ribs, sternum, pelvis |
| Irregular | Do not fit into other categories; complex shapes | Various - protection, support, muscle attachment | Vertebrae, some facial bones |
Sporting Example
Long bones as levers: When a swimmer performs a front crawl, the humerus (long bone) acts as a lever. The deltoid and latissimus dorsi muscles pull on the humerus to generate the pulling action through the water.
Flat bones for protection: A cricketer wearing a helmet relies on the cranium (flat bone) to protect the brain from impact if struck by a ball.
🦻 The Vertebral Column
The vertebral column consists of 33 vertebrae stacked on top of each other, separated by intervertebral discs that act as shock absorbers.
It is divided into five regions:
| Region | Number of Vertebrae | Function |
|---|---|---|
| Cervical | 7 | Supports the head and allows nodding and rotation (e.g. nodding head in heading a football) |
| Thoracic | 12 | Attaches to the ribs; protects heart and lungs; allows limited rotation |
| Lumbar | 5 | Supports body weight; allows flexion, extension and lateral flexion (e.g. arching back in a handstand) |
| Sacral | 5 (fused) | Connects to the pelvis; transfers weight from upper body to legs |
| Coccyx | 4 (fused) | Attachment for pelvic floor muscles; remnant of a tail |
Remember: Cervical = 7, Thoracic = 12, Lumbar = 5 = "Breakfast at 7, Lunch at 12, Dinner at 5"
🔗 Key Bones for GCSE PE
You must be able to identify and locate the following bones:
Upper Body
- Cranium - skull, protects the brain
- Clavicle - collarbone, connects shoulder to sternum
- Scapula - shoulder blade, attachment for rotator cuff muscles
- Humerus - upper arm bone, acts as lever for throwing
- Radius - thumb side of forearm, rotates for pronation/supination
- Ulna - little finger side of forearm, forms elbow hinge with humerus
- Sternum - breastbone, protects heart; attachment for ribs
- Ribs - 12 pairs, protect lungs and heart
Lower Body
- Pelvis - hip girdle, supports organs; attachment for leg muscles
- Femur - thigh bone (longest and strongest bone in the body)
- Patella - kneecap (sesamoid bone), protects knee joint
- Tibia - shin bone, weight-bearing bone of lower leg
- Fibula - smaller lower leg bone, not weight-bearing; muscle attachment
- Tarsals - ankle bones (7 short bones)
- Metatarsals - foot bones (5 long bones)
- Phalanges - toe bones (14 in each foot)
🧪 Bone Structure
Long bone structure: A long bone has an outer layer of compact bone (dense and strong) and an inner layer of spongy bone (light and shock-absorbing). The shaft is called the diaphysis and the ends are called epiphyses.
- Compact bone - Dense, hard outer layer; provides strength and resists bending
- Spongy (cancellous) bone - Honeycomb structure inside; reduces weight while maintaining strength
- Red bone marrow - Found in spongy bone at ends of long bones; produces blood cells
- Yellow bone marrow - Found in the medullary cavity of the shaft; stores fat
- Periosteum - Tough outer membrane; contains blood vessels and nerves; attachment point for tendons
- Cartilage - Covers the ends of bones at joints; reduces friction and absorbs shock
❓ Practice Questions
Q1: Name the five functions of the skeleton.
Q2: How many bones make up the axial skeleton?
Q3: Give one example each of a long bone, a short bone, a flat bone and an irregular bone.
Q4: Explain why the vertebral column is classified as irregular bones.
Q5: Which part of the vertebral column supports the most body weight, and why?
Q6: Describe how the skeleton supports blood cell production.
✅ Answers
- Support, protection, movement, mineral storage, blood cell production.
- 80 bones make up the axial skeleton.
- Long: femur; Short: carpals; Flat: cranium; Irregular: vertebrae.
- Vertebrae have complex, irregular shapes that do not fit into the long, short, or flat categories. Each vertebra has a body, spinous process, transverse processes and a vertebral foramen, making their shape irregular.
- The lumbar region (5 vertebrae) supports the most body weight because it bears the entire weight of the upper body and transfers it to the pelvis and legs.
- Red bone marrow, found in the sternum, ribs, pelvis, vertebrae and the ends of long bones, produces red blood cells (carry oxygen), white blood cells (fight infection) and platelets (help blood clot).
🎯 Exam Tips
- Always use the correct scientific names for bones (e.g. femur, not "thigh bone")
- Link bone classification to function - examiners want to see you understand WHY a bone is shaped that way
- The mnemonic "Breakfast at 7, Lunch at 12, Dinner at 5" helps remember cervical/thoracic/lumbar vertebrae counts
- When asked about functions, state all five - don't just list two or three
- Know the difference between axial (80) and appendicular (126) skeleton bone counts
- Be ready to explain how bone shape relates to function in sporting contexts
⚠️ Common Errors
Watch Out!
Students often confuse the pelvis as part of the axial skeleton because it is in the centre. Wrong: "The pelvis is part of the axial skeleton." Correct: "The pelvis is part of the appendicular skeleton."
Students often forget mineral storage and blood cell production as functions. Wrong: "The skeleton has three functions: support, protection and movement." Correct: "The skeleton has five functions: support, protection, movement, mineral storage and blood cell production."
Students often confuse short bones with small bones. Phalanges are small but classified as long bones. Wrong: "Phalanges are short bones because they are small." Correct: "Phalanges are long bones - their length is greater than their width."
📝 Exam Technique
PE Exam Tips — The Skeletal System:
1. For The Skeletal System questions, use subject-specific terminology precisely
2. Support every point with specific evidence or examples
3. Show balanced analysis — consider different perspectives before reaching a conclusion
4. Link your understanding of The Skeletal System to real-world contexts where possible
5. For longer answers, plan your response to address all parts of the question
1. For The Skeletal System questions, use subject-specific terminology precisely
2. Support every point with specific evidence or examples
3. Show balanced analysis — consider different perspectives before reaching a conclusion
4. Link your understanding of The Skeletal System to real-world contexts where possible
5. For longer answers, plan your response to address all parts of the question
⚠️ Common Errors
Watch Out!
Students often think lactic acid causes doms. Wrong: Lactic acid causes DOMS Correct: DOMS (delayed onset muscle soreness) is caused by micro-tears in muscle fibres, not lactic acid. Lactic acid is cleared within an hour of exercise.
Students often think veins always carry deoxygenated blood. Wrong: Veins always carry deoxygenated blood Correct: Pulmonary veins carry oxygenated blood from the lungs to the heart. It is arteries and veins relative to the heart that matters, not oxygenation.
Students often think the heart beats faster during exercise just because you need more oxygen. Wrong: The heart beats faster during exercise just because you need more oxygen Correct: Heart rate increases due to anticipatory rise (before exercise), increased CO2 in blood detected by chemoreceptors, and decreased vagal tone. It is a coordinated response, not just oxygen demand.
✍️ Model Answer
Full-Mark Response
6 marks: Explain how the skeletal system affects sporting performance.
The Skeletal System has significant effects on sporting performance. [Key concept 1]: explain the mechanism with specific detail. [Key concept 2]: how this applies in a named sporting example. [Key concept 3]: the relationship between this topic and overall performance. A grade 9 answer uses precise anatomical/physiological terminology, specific sporting examples, and evaluates the relative importance of different factors.
Mark scheme: 2 marks per explained point with specific evidence, evaluation for top marks
📊 AO Deep Dive
Assessment Objective Analysis
GCSE PE tests four AOs: AO1 (Knowledge, 30%) — recall facts about The Skeletal System including definitions, classifications and specific examples; AO2 (Application, 30%) — apply knowledge to sporting contexts and training scenarios; AO3 (Analysis and Evaluation, 25%) — analyse data (graphs, tables), evaluate training methods or strategies, and justify recommendations; AO4 (Practical, 15%) — demonstrate relevant skills. For grade 9, use precise terminology, support every point with named sporting examples, and evaluate rather than just describe. The difference between grade 5 and grade 9 is the quality of application and depth of evaluation.
📝 Exam Questions by Topic
🎬 Video Resources
Ready to ace your GCSE PE exams?
Get the best revision books and guides to boost your grades.