Respiratory System

Question 1

3 major functions of the respiratory system

Answer 1

• Gas exchange
• Filtration of some matter
• Thermoregulation

Question 2

Structures of the respiratory tract (in order)

Answer 2

1. Nasal passage
2. Pharynx (digestion)
3. Larynx (voice box; cartilagenous)
4. Trachea
5. Bronchi
6. Bronchioles
7. Alveoli (relevant to surface tension: tendency of liquid molecules to associate with each other)

Question 3

What substance serves to decrease surface tension in the alveoli?

Answer 3

Surfactant decreases surface tension and prevents the alveoli from collapsing

Question 4

Which gas does pulmonary capillaries have a high partial pressure of

Answer 4

Carbon dioxide

(Pulmonary capillaries bring deoxygenated blood)

Question 5

Inspiration

Answer 5

1. The diaphragm (flattens downward) and external intercostal muscles (push outwards) contract, expanding the thoracic activity
2. The lungs expand along with the surrounding cavity, lowering internal pressure
3. Air flows in due to low internal pressure

Mechanism: negative pressure breathing

Question 6

Expiration

Answer 6

• Normal expiration is passive, requiring no muscular involvement
• If consciously forced, it involves the internal intercostal muscles
• The diaphragm is relaxed (pushing upward and decreasing thoracic cavity)

Question 7

Measurement describes the volume of air inhaled per breath

Answer 7

Tidal volume