Body in Action

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Body in Action

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• Sub-topic (a) Movement
• State the functions of the skeleton.
• To protect vital organs. For example the ribcage
  protects the heart and lungs.
• To provide support.
• To provide a framework for muscle attachment.
• Describe the range of movement allowed by the
  hinge and ball and socket joints.
• A hinge joint (knee) can only move in one plane.
• A ball and socket joint (hip) can move in three
  planes.

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• State the functions of ligaments and cartilage.
• The ligament attaches bone to bone across a
  joint.
• The cartilage acts as a shock absorber (soft
  cushioning) at the end of a bone at a joint.
• Describe the composition of bone.
• Bone is composed of living cells which make up
  flexible fibres and hard minerals such as calcium
  phosphate.
• Describe how muscles are attached to bones.
• Muscles are attached to bone by inelastic tissues
  called tendons.

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• Describe how muscles bring about movement.
• To bend an arm, for example, the bicep would
  contract while at the same time the tricep would
  relax bending the arm. To straighten the arm the
  bicep would relax while at the same time the
  tricep would contract.

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Air sac
Blood capillaries
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• Describe the features that make capillary
  networks efficient at gas exchange.
• Capillaries are very narrow tubes which branch
  repeatedly, forming such a dense network that
  that every living body cell is close to a
  capillary.
• The combined surface area of the capillary
  network is enormous and the capillary walls are
  only one cell thick.
• These properties of the capillary network will
  allow efficient gas exchange to occur between the
  bloodstream and the body cells.

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• Describe the function of the components of the
  blood.
• Plasma
• Contains dissolved substances (amino acids,
  glucose etc.) and blood cells.
• Red Blood Cells
• Carry oxygen around the body.
• White Blood Cells
• Fight infection.
• Platelets
• Clot blood to stop bleeding at a wound.

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• Describe the exchange of gases between body cells
  and capillaries.
• As oxygenated blood flows through a capillary
  close to a body cell, oxygen diffuses out of the
  capillary into the surrounding cells.
• During respiration the cells produce carbon
  dioxide. The carbon dioxide diffuses out of the
  cells and into the capillary.
• Carbon dioxide is then transported to the lungs
  in the blood.

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• Sub-topic (c) Coordination
• State the benefit of having two eyes and two
  ears.
• Two eyes allow accurate judgement of distances.
• Two ears allow accurate judgement of the
  direction of sound.
• Identify the parts of the eye and state their
  function.
• Cornea
• Allows light to enter the eye.
• Iris
• Coloured part containing muscle. Controls amount
  of light entering the eye.

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Iris
Cornea
Optic nerve
Pupil
Lens
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• Sub-topic (c) Coordination
• Describe how the structure of semi-circular
  canals is related to their function.
• The three liquid filled canals are situated at
  right angles to one another.
• Each contains an ampulla containing a receptor
  which is stimulated by movements of the liquid in
  the canal.
• These are caused by the canal being rotated in
  its respective plane by movements of the head.
• Messages are carried by a branch of the auditory
  nerve to a region of the brain that controls
  muscular activity for balance.

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Nerves throughout the body
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Relay nerve
Sensory nerve
Motor nerve
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Cerebrum
Cerebellum
Medulla
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• Sub-topic (d) Changing levels of performance
• Explain muscle fatigue in terms of anaerobic
  respiration.
• Under normal circumstances the energy needed for
  contraction of muscles comes from aerobic
  respiration (glucose and oxygen).
• During vigorous exercise the supply of oxygen
  cannot meet the demand.
• Muscles will continue to use glucose
  anaerobically producing lactic acid and a little
  energy.
• Oxygen debt is required to remove the lactic acid
  so that muscles can work properly.

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• Explain the relationship between the effects of
  training and recovery time.
• Recovery time is the time it takes for the heart
  rate, breathing rate and the lactic acid levels
  to return to normal resting values.
• A person who is in training will notice that the
  factors above will return to normal resting
  values quicker than a person who is not in
  training.
• It can therefore be used as an indicator of
  fitness.

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• State the effects of training on the lungs and
  circulation.
• Training involves vigorous exercise over a period
  of several weeks.
• The lungs of an athlete are more efficient able
  to take in larger volumes of oxygen in each
  breath.
• During training the heart muscle tissue gradually
  increases in strength and efficiency.
• As a result the same volume of blood can be
  supplied to the muscles using fewer heartbeats.
• Therefore the athletes circulation is more
  efficient.