ZIMSEC O Level · Physical Education, Sport and Mass Displays · Form 1, Form 2
The skeleton
Functions: support, protection (the skull protects the brain; ribs protect the heart and lungs), movement (with muscles), making blood cells and storing minerals.
Joints: ball and socket (shoulder, hip – movement in all directions), hinge (knee, elbow – bending and straightening), pivot (neck – rotation).
Muscles
Muscles pull, never push, so they work in antagonistic pairs: when the biceps contracts, the triceps relaxes to bend the arm, and the reverse to straighten it. Tendons join muscle to bone; ligaments join bone to bone.
Heart and circulation
The heart pumps blood carrying oxygen and nutrients to muscles. Resting heart rate is usually about 60–80 beats per minute; trained athletes often have lower resting rates. Maximum heart rate is roughly 220 minus age.
Lungs and breathing
Oxygen is taken in and carbon dioxide removed. During exercise, breathing rate and depth increase.
Effects of exercise
Short-term: faster heart rate and breathing, sweating, muscle fatigue. Long-term: stronger heart, larger lung capacity, stronger bones and muscles, better posture and healthy body weight.
Check yourself
- Name the type of joint found at the knee.
- Explain what is meant by antagonistic muscles.
- Estimate the maximum heart rate of a 16-year-old.
Show answers
- A hinge joint.
- Muscles working in pairs – one contracts while the other relaxes.
- 220 − 16 = 204 beats per minute.
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