Circulatory system exercise for Grade 6 - Free Printable

Let's solve this circulation diagram step by step.

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🔍 Understanding the Circulatory System

This diagram shows the human circulatory system, focusing on the path of blood through the heart and lungs. The key components are:

- Deoxygenated blood (blue) → flows from body → heart → lungs → oxygenated
- Oxygenated blood (red) → flows from lungs → heart → body

The heart has four chambers:
1. Right atrium
2. Right ventricle
3. Left atrium
4. Left ventricle

Blood flow path:
1. Body → Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs
2. Lungs → Pulmonary veins → Left atrium → Left ventricle → Aorta → Body

Also included:
- Capillaries: tiny vessels where gas exchange occurs (in lungs and body)
- Lung: site of gas exchange
- Aorta: main artery carrying oxygenated blood from left ventricle to body

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🧩 Step-by-step Labeling

We have 7 blank boxes to fill with the correct terms from the list:

> Words to use:
> - Left ventricle
> - Right atrium
> - Aorta
> - Left atrium
> - Capillaries
> - Lung
> - Right ventricle

Now, let’s identify each blank based on the diagram.

#### 1. Top right box (pointing to the lungs)
→ Clearly labeled as Lung

✔ Answer: Lung

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#### 2. Second box from top right (pointing to the red vessel going from heart to lungs)
→ This is the pulmonary artery, but the label isn't for the vessel — it's pointing to the blood flow into the lungs. However, the only structure here that makes sense is the capillaries in the lung.

But wait — the lungs already have a label. So what's next?

Looking at the path:

- Blood goes from right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium

So the blue vessel entering the lungs comes from the right ventricle, and the red vessel leaving the lungs goes to the left atrium.

But we need to match the labels to the structures shown.

Let’s go from top to bottom.

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✔ Labeling Each Box

Let’s number the boxes from top to bottom on the right side, then left side, then bottom.

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#### 🔹 Box 1 (top right) – points to the lungs
→ Clearly the Lung

✔ Lung

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#### 🔹 Box 2 (middle right) – points to the red vessel going from heart to lungs
Wait — no, actually, look carefully:

- The red vessel coming from the heart to the lungs? That’s not correct.

Actually:
- Blue = deoxygenated blood
- Red = oxygenated blood

So:
- Blue vessel goes from heart to lungs → pulmonary artery
- Red vessel comes from lungs to heart → pulmonary vein

So the red vessel going into the heart from the lungs → enters the left atrium

So the box pointing to the red vessel near the heart (top right) → must be Left atrium

Wait — let’s trace:

- The red vessel from the lungs connects to the heart → Left atrium

Yes!

So:

#### 🔹 Box 2 (middle right) – points to the red vessel entering the heart from lungs
→ This is the pulmonary vein, which leads to the Left atrium

✔ Left atrium

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#### 🔹 Box 3 (bottom right) – points to the large red vessel exiting the heart
→ This is the aorta, which carries oxygenated blood from the left ventricle to the body

✔ Aorta

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#### 🔹 Box 4 (bottom right) – points to the red chamber in the heart
→ This is the Left ventricle (it pumps blood into the aorta)

✔ Left ventricle

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Now, left side:

#### 🔹 Box 5 (left side, upper) – points to the blue chamber in the heart
→ This is the Right atrium (receives deoxygenated blood from body)

✔ Right atrium

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#### 🔹 Box 6 (left side, lower) – points to the blue chamber below the right atrium
→ This is the Right ventricle (pumps blood to lungs)

✔ Right ventricle

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#### 🔹 Box 7 (bottom left) – points to the network of small vessels in the body
→ This is the Capillaries (where exchange happens in tissues)

✔ Capillaries

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✔ Final Answers (by position):

From top to bottom, right to left, matching the lines:

1. Top right → Lung
2. Middle right → Left atrium
3. Bottom right (vessel) → Aorta
4. Bottom right (chamber) → Left ventricle
5. Left side, upper chamber → Right atrium
6. Left side, lower chamber → Right ventricle
7. Bottom left (body network) → Capillaries

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✔ Final Answer Key:

| Box Position | Correct Label |
|--------------|---------------------|
| Top right | Lung |
| Middle right | Left atrium |
| Bottom right (vessel) | Aorta |
| Bottom right (chamber) | Left ventricle |
| Left upper | Right atrium |
| Left lower | Right ventricle |
| Bottom left | Capillaries |

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📌 Summary of Blood Flow:

1. Body → Capillaries → Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lung → Pulmonary veins → Left atrium → Left ventricle → Aorta → Body

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✔ All words used exactly once.

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