Anatomy of the Respiratory System

Question 1

What are the four main functions of the respiratory system?

Answer 1

1. gas exchange
2. thermoregulation (regulation of body temperature)
3. protection against disease (traps harmful particulate matter and prevents it from entering the body)
4. control pH (via bicarbonate buffer system)

Question 2

What is the passage of air into the respiratory system?

Answer 2

Question 3

What is the function of alveoli in the respiratory system?

Answer 3

Site of gas exchange in the lungs.

• Alveoli give O₂ to the RBCs.
• RBCs give CO₂ to the alveoli.

Question 4

Each alveolus in the lung is covered with surfactant. What is the function of surfactant?

Answer 4

Lowers surface tension (for easy gas exchange) and prevents the alveolus from collapsing on itself.

Question 5

The epiglottis functions in both the respiratory and digestive systems. What is its function?

Answer 5

Covers the larynx (voice box) during swallowing.

(closes to prevent food from entering the respiratory system.)

Question 6

What are the three membranes of the lung?

Answer 6

1. visceral pleura (right next to it)
2. intrapleura space (contains a thin layer of fluid that decreases friction)
3. parietal pleura (outer)

**Think of a deflated balloon (pleuras) and fist (lung) example.**

Question 7

The lungs have resiliency. What does that mean?

Answer 7

The lungs are elastic and recoil as soon as you relax after inhalation.

Question 8

What are the two most important muscles in the body for respiration?

Answer 8

1. external and internal intercostal muscles
2. diaphragm

Question 9

Which muscles are involved in inhalation? Exhalation?

Answer 9

• Inhalation: external intercostal muscles and diaphragm
• Exhalation: internal intercostal muscles, abdominal muscles and diaphragm

Question 10

Is inhalation (or inspiration) an active or passive process?

Answer 10

Active process

Because it requires skeletal muscle contraction (diaphragm) which uses ATP and is therefore, an active process.

Question 11

Is exhalation (or expiration) an active or passive process?

Answer 11

Passive process

During forced respiration, this process can be sped up using the internal intercostal muscles and abdominal muscles.

Question 12

Explain how differential pressure is created during inhalation.

Answer 12

1. diaphragm contracts (or “flattens”)
2. chest cavity volume increases
3. alveoli stretch open
4. The negative pressure in the chest cavity forces air to flow into the lungs.

Pressure and volume of gases are inversely proportional [Boyle’s law]. So when internal air and lung pressure decrease below atmospheric pressure due to the increase in the chest cavity volume, air rushes into the lungs to equalize the imbalance.

Question 13

Explain how differential pressure is created during exhalation.

Answer 13

1. diaphragm and internal intercostal muscles relaxes
2. chest cavity volume decreases
3. alveoli recoil
4. The positive pressure in the chest cavity forces air to flow out of the lungs.

Pressure and volume of gases are inversely proportional [Boyle’s law]. So when internal air and lung pressure increase above atmospheric pressure due to the decrease in the chest cavity volume, air rushes out of the lungs to equalize the imbalance.

Question 14

What does Boyle’s Law state?

Answer 14

The pressure and volume of gases are inversely proportional.