Formative Practice 10.3 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
Name the main heart pacemaker.

Sinoatrial node

Question 2:
What does the term myogenic mean?

Myogenic means the heart contracts and relaxes without receiving any impulse signal from the nervous system.

Question 3:
Explain why a person who stands too long may faint.

The blood flow back to the heart requires the contraction of skeletal muscles around the veins. If someone stands on his/her feet for too long, less oxygen flows to the brain, hence less oxygen and glucose are transported to the brain. This causes the individual to pass out.

Question 4:
In what circumstances would fingers turn pale?

When the blood flow is obstructed from flowing to the fingertips or when the blood vessels contract due to coldness.

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