Explain how the heart's structure supports blood flow during a 400 metre sprint. (6 marks)
--- 18 WORK AREA LINES (style=lined) ---
Show Answers Only
Sample Answer
- The heart’s four-chamber structure separates oxygenated and deoxygenated blood, which ensures muscles receive only oxygen-rich blood during sprinting.
- The left ventricle’s thick muscular walls enable powerful contractions, therefore generating high pressure to pump blood throughout the body.
- During a 400m sprint, these thick walls allow stroke volumes to double, resulting in increased oxygen delivery to working muscles.
- Four one-way valves slam shut between beats, which prevents backflow despite rapid heart rates during sprinting.
- This valve function is crucial because it maintains forward blood flow even when heart rate increases dramatically.
- Coronary arteries branch immediately from the aorta, consequently prioritising oxygen delivery to the heart muscle during extreme demand.
- The aorta’s elastic nature allows it to stretch with each contraction then recoil, which maintains blood pressure between beats.
- Atrial chambers act as primer pumps, ensuring ventricles fill completely despite shortened filling time.
- As a result, this coordinated structure enables cardiac output to increase five-fold during maximal sprinting.
Show Worked Solution
Sample Answer
- The heart’s four-chamber structure separates oxygenated and deoxygenated blood, which ensures muscles receive only oxygen-rich blood during sprinting.
- The left ventricle’s thick muscular walls enable powerful contractions, therefore generating high pressure to pump blood throughout the body.
- During a 400m sprint, these thick walls allow stroke volumes to double, resulting in increased oxygen delivery to working muscles.
- Four one-way valves slam shut between beats, which prevents backflow despite rapid heart rates during sprinting.
- This valve function is crucial because it maintains forward blood flow even when heart rate increases dramatically.
- Coronary arteries branch immediately from the aorta, consequently prioritising oxygen delivery to the heart muscle during extreme demand.
- The aorta’s elastic nature allows it to stretch with each contraction then recoil, which maintains blood pressure between beats.
- Atrial chambers act as primer pumps, ensuring ventricles fill completely despite shortened filling time.
- As a result, this coordinated structure enables cardiac output to increase five-fold during maximal sprinting.