Lesson focus: The skeletonThe frame of bones that supports and protects the body. is living tissueA group of similar cells working together to do a job, such as muscle tissue. that supports, protects and enables movement.
Identify major bones and relate bone structure to function.
Build on earlier learning
Levels of organisationApply levels of organisation to bone tissue, bones and the skeletal system.
You will be successful when you can…
- Name major bones.
- Explain support, protection and movement roles.
- Distinguish compact bone and marrow.
- Interpret a strength-to-mass comparison.
Words that carry the science
- skeleton
- Framework of bones and associated structures.
- compact bone
- Dense outer bone tissue providing strength.
- bone marrow
- Soft tissue in bone cavities; red marrow produces blood cells.
- joint
- Region where two or more bones meet.
- leverage
- Turning effect produced when forces act around a joint.
Treat bone as living engineered tissue
01More than a frame
The skeletonThe frame of bones that supports and protects the body. supports the body, protects organs and provides attachment and levers for muscles. The skull protects the brain, ribs protect heart and lungs, and vertebrae surround the spinal cord. Three main jobs of the skeleton: protection (the skull protects the brain; the ribs protect the heart and lungs), support (it holds the body up) and movementOne of the life processes: all living things can move all or part of themselves. (muscles pull on bones to move them).
Bones store minerals and contain marrow; they are living organs with cells, blood vessels and several tissues.
02Major bones reflect mechanical roles
The humerus is in the upper arm; radius and ulna are in the forearm. The femur is in the thigh; tibia and fibula are in the lower leg. The pelvis transfers loads and protects pelvic organs.
03Strong without unnecessary mass
Long bones combine dense compact boneThe hard, dense outer layer of a bone that makes it strong. with internal spaces and marrow. Material distribution can resist bending without being completely solid.
Compare beam designs
A solid model supports 120 N at 60 g; a hollow model supports 100 N at 30 g.
- Solid strength per gram = 120 ÷ 60 = 2.0 N/g.
- Hollow strength per gram = 100 ÷ 30 ≈ 3.3 N/g.
- The solid carries more total load.
- The hollow model has greater load capacity per unit mass.
How to make the reasoning visible: A design judgement depends on whether total strength or strength-to-mass ratio matters.
Bone function evidence
Link structure to protection or movement.
| Structure | Organ protected/role | Mechanism |
|---|---|---|
| Skull | Brain | Rigid enclosure resists impact |
| Rib cage | Heart and lungs | Curved cage combines protection and movement |
| Vertebral column | Spinal cord/support | Stacked vertebrae surround cord and bear load |
| Femur | Support and movement | Strong long bone acts as lever |
Why are ribs not fused into one solid shell?
What does marrow do?
Use the table. Which part of the skeleton protects the spinal cord, and how?
Check your understanding
Answer from memory, then check against the suggested answer.
Which bone is in the thigh?
What protects the spinal cord?
What is compact bone?
What protects the brain?
Name the two bones in the forearm.
Why can a long bone be relatively light yet resist bending?
Which beam is better in the worked example?
Why are bones like the femur not completely solid?
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Answer the parts to explain two jobs of the skeleton.
Which bone protects the brain?
(1)Which bones protect the heart and lungs?
(1)How do bones help you move?
(1)Give one more job of the skeleton.
(1)Total for this question: 4 marks
Command word: Name the bone and say how it does its job.