Question
SLPaper 2
1.[2]
Label X and Y on the diagram of the heart.
Verified
Solution
: pulmonary artery
2.[2]
The heart responds quickly to physical activity. Describe how heart rate is controlled to meet the increased circulatory demands.
Verified
Solution
- Nerve impulse from medulla/brain acts on heart/right atrium;
1 mark - Pacemaker/sinoatrial node/SAN increases/controls contraction of heart;
1 mark - Epinephrine/adrenaline «rapidly» increases heart rate;
1 mark
3.[3]
Explain how the circulatory system is able to transport the blood under high pressure from the heart to the rest of the body.
Verified
Solution
- Contraction of ventricle creates high pressure;
1 mark - Blood at high pressure is carried out of the heart through arteries;
1 mark - Thick muscular walls of arteries resist pressure/prevent leaks;
1 mark - Elastic recoil of arterial walls helps to push blood;
1 mark - Narrow lumen of arteries maintain pressure;
1 mark
