Diagram 2 illustrates key components of an ECG waveform, highlighting the P wave, QRS complex, and T wave.

Let’s figure out what each number is pointing to on this ECG (heart rhythm) diagram.

First, remember that a normal heartbeat on an ECG has three main parts:
- The P wave — small bump before the big spike
- The QRS complex — the big sharp up-and-down spike
- The T wave — smaller rounded bump after the spike

Now let’s look at each labeled part:

→ Number 6: This arrow points to the first small upward curve. That’s the P wave. It shows the atria (top chambers of the heart) contracting.

→ Number 7: These arrows point to the beginning and end of the big spiky part. That whole section is called the QRS complex. It shows the ventricles (bottom chambers) contracting.

→ Number 8: This arrow points to the flat line right after the QRS complex, before the next bump starts. That’s the ST segment. It’s important because doctors check it to see if the heart muscle is getting enough oxygen.

So now we can label them correctly:

Final Answer:
6. P wave
7. QRS complex
8. ST segment