a: right atrium ~
b: timer
What:
"The sinoatrial node (SA node) in the right atrium is like a tiny in-built 'timer'. It fires off an electrical impulse at regular intervals. (About 60-80 per minute when you are resting and faster when you exercise. This controls your heart rate.) Each impulse spreads across both atria, which causes them to contract. This pumps blood through one-way valves into the ventricles."
Useful?
Writer: Not Stated
LCC:
Where:
Date: Apr 21 2016 9:36 AM
# 9812 Critique Analogy