What's covered
Key facts
Regular aerobic exercise strengthens the heart muscle over time, increasing the blood pumped per beat.
In an antagonistic muscle pair the relaxing muscle lengthens to allow the contracting (agonist) muscle to move the joint.
During respiration we breathe in oxygen, which the body needs to release energy from food.
The bicep is the muscle at the front of the upper arm; it flexes (bends) the elbow.
Carbon dioxide is the waste gas breathed out as a product of respiration.
When you bend (flex) your arm at the elbow, the bicep contracts (agonist) and the tricep relaxes (antagonist).
During exercise both breathing rate and breathing depth increase — we breathe faster and more deeply to take in more oxygen.
Cartilage covers the ends of bones at a joint, cushioning them and protecting them from wear and friction.
Cardiac output is the volume of blood the heart pumps per minute (heart rate × stroke volume).
Extension is the joint movement that increases the angle at a joint — straightening a limb.
Sample questions
A taste of the 29 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What is the main job of the heart?
- •To absorb oxygen from the air
- •To produce blood cells
- ✓To pump blood around the body
- •To remove carbon dioxide from the lungs
Which bone protects the brain?
- •Femur
- •Rib cage
- ✓Skull
- •Spine
How do you measure your pulse to find your heart rate?
- ✓Count the beats felt at the wrist or neck for one minute
- •Measure how fast you are breathing
- •Place your hand on your chest and count chest rises
- •Use a thermometer to check body temperature
Which bone is the longest in the human body?
- ✓Femur (thigh bone)
- •Fibula (outer lower leg)
- •Humerus (upper arm)
- •Tibia (shin bone)
Why does heart rate increase during exercise?
- •To lower blood pressure and prevent the risk of fainting during effort
- •To reduce the amount of oxygen being used by the working muscles
- •To slow breathing rate and conserve energy for the effort ahead
- ✓Working muscles need more oxygen and produce more carbon dioxide
What are the four main functions of the skeleton?
- •Balance, strength, speed, coordination
- •Breathing, digestion, circulation, temperature
- •Support, flexibility, energy storage, cooling
- ✓Support, protection, movement, blood cell production
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