key knowledgekey skills the functions responsible for short term (acute) responses to physical...

KEY KNOWLEDGE KEY SKILLS

The functions responsible for short term (acute) responses to physical activity in the cardiovascular, respiratory and muscular systems.

Participate in data collection, analyse and report on the acute responses occurring at the cardiovascular, respiratory and muscular systems in response to exercise.

© Cengage Learning Australia 2011

© Cengage Learning Australia 2011

• only occur for the duration of exercise and recovery

• are dependent on the intensity, duration and type of exercise being undertaken

• involve the respiratory, cardiovascular and muscular systems working together to supply more energy / ATP and oxygen to working muscles and then again to remove any waste products

Acute responses –

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↑ Ventilation (air breathed in and out per minute)

ventilation (L/min) = tidal volume (L) x respiratory rate (breaths/min)

↑Tidal volume ( amount of inspired and expired air per breath)

↑ Respiratory rate (breaths per minute)

Acute respiratory responses

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Gases such as oxygen and carbon dioxide always move from areas of high pressure to areas of low pressure.

↑ Gas exchange/diffusion

Lungs• oxygen concentration is high so it moves from the alveoli

into the blood stream to be taken to muscles• carbon dioxide concentration in the blood stream is high so

it moves into the alveoli to be exhaled.

Muscles (opposite concentrations to lungs)• oxygen concentration is low so it moves from the blood

stream to be taken in by the muscles• carbon dioxide concentration in the muscles is high so it

moves into the blood stream to be transported to the lungs and exhaled.

© Cengage Learning Australia 2011

© Cengage Learning Australia 2011

↑ stroke volume (mL of blood pumped out of the left ventricle per beat)

↑ heart rate (beats per minute)

↑ cardiac output (litres per minute) = SV x HR

Acute cardiovascular responses

© Cengage Learning Australia 2011

© Cengage Learning Australia 2011

↑ blood pressure (mainly systolic)

↑ venous return to heart (assisted by muscle pump, respiratory pump and venoconstriction – still approx 4% but 5 times as much blood compared to rest)

↓ blood volume (plasma loss)

↑ blood directed towards working muscles (vasoconstriction of arterioles supplying inactive muscles reduces blood flow here and vasodilation of arterioles supplying muscles increases blood flow here)

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↑ increased blood flow to working muscles

↑ motor unit/fibre recruitment

↓ fuel stores (PC, ATP, glycogen, triglycerides)

↑ lactate production (then ↑ H+ if not removed)

↑ muscle temperature

↑ oxygen consumption

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The greater the extraction of oxygen by working muscles, the greater the a-vO2 diff.

↑ Arteriovenous oxygen difference (a-vO2 diff)

© Cengage Learning Australia 2011

© Cengage Learning Australia 2011