Human Respiratory System - Worksheet | Printable and Distance ... - Free Printable

Let's solve Q.3 and Q.4 step by step.

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✔ Q.3: Label the parts of the human respiratory system on the diagram below.

We are given a list of structures to label:

- Throat
- Bronchi
- Bronchiole
- Larynx
- Trachea
- Lungs
- Mouth
- Epiglottis
- Nose
- Nasal cavity
- Alveoli
- Esophagus

Now, let’s match each part to its correct location in the diagram based on anatomy.

#### Step-by-step labeling (from top to bottom):

1. Nose – The external opening at the top of the face.
2. Nasal cavity – Inside the nose; air passes through here.
3. Mouth – The oral opening below the nose.
4. Throat – Also called the pharynx; common passage for air and food.
5. Epiglottis – Flap that covers the larynx during swallowing (located just above the larynx).
6. Larynx – Voice box; located below the throat.
7. Trachea – Windpipe; extends from larynx down into the chest.
8. Bronchi – Two main branches from trachea entering each lung.
9. Lungs – Large organs on both sides of the chest.
10. Bronchiole – Smaller branches inside the lungs (from bronchi).
11. Alveoli – Tiny air sacs at the end of bronchioles where gas exchange occurs.
12. Esophagus – Tube behind the trachea that carries food to the stomach.

Now, place these labels on the diagram:

- Top left: Nose
- Below nose: Nasal cavity
- Right side, near mouth: Mouth
- Behind mouth, leading down: Throat (Pharynx)
- Just below throat: Epiglottis
- Below epiglottis: Larynx
- Vertical tube going down neck: Trachea
- Splitting into two tubes entering lungs: Bronchi
- Large organs in chest: Lungs
- Smaller branching tubes within lungs: Bronchiole
- Tiny sacs shown in magnified inset: Alveoli
- Tube running behind trachea: Esophagus

> 📌 Note: The esophagus is not directly involved in respiration but runs alongside the trachea and is included because it's anatomically close.

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✔ Q.4: Where is the site of gas exchange in the lungs?

Options:
a) Larynx
b) Bronchi
c) Alveoli
d) Trachea

#### Correct Answer: c) Alveoli

#### Explanation:
- Gas exchange (oxygen entering blood and carbon dioxide leaving) occurs in the alveoli.
- The alveoli are tiny, thin-walled air sacs surrounded by capillaries.
- Oxygen from inhaled air diffuses into the bloodstream, while carbon dioxide from the blood diffuses into the alveoli to be exhaled.
- Other structures like the trachea, bronchi, and larynx are conduits for air but do not perform gas exchange.

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✔ Final Answers:

#### Q.3: Labels (from top to bottom / as per diagram):
1. Nose
2. Nasal cavity
3. Mouth
4. Throat (Pharynx)
5. Epiglottis
6. Larynx
7. Trachea
8. Bronchi
9. Lungs
10. Bronchiole
11. Alveoli (in inset)
12. Esophagus (behind trachea)

#### Q.4: c) Alveoli

✔ Answer: c) Alveoli — This is the site of gas exchange in the lungs.