Respiratory System

Question 1

How many lobes does each lung have?

Answer 1

Right has three, left has two (to make space for the heart)

Question 2

What is the pleural sac?

Answer 2

A double-walled enclosure of the lungs filled with fluid (pleural fluid)

Question 3

What are the functions of the pleural sac?

Answer 3

• Reduces friction from movement on the surface of the lungs

• Fixes lungs firmly on the thoracic wall without any physical attachments

Question 4

Name the airways from largest to smallest

Answer 4

• Trachea

• Bronchi

• Bronchioles

• Terminal bronchioles (end of conducting zone)

• Respiratory bronchioles (start of respiratory zone)

• Alveolar ducts

• Alveolar sacs

Question 5

What are the functions of the airways?

Answer 5

• Warming up inspired air

• Humidification of dry inspired air

• Filtration of inhaled foreign materials

Question 6

What are the factors affecting airway radius?

Answer 6

• Bronchodilation: CO2, epinephrine (via b2 receptors)

• Bronchoconstriction: parasympathetic stimulation (via muscarinic receptors), histamine

Question 7

What pressure must be positive for the lungs?

Answer 7

Transpleural pressure

Question 8

What law causes the lungs to require surfactant?

Answer 8

• Law of LaPlace (P = 2T/r)
• The smaller alveoli would have more pressure as their radii are smaller, so would collapse into the larger alveoli

Question 9

What is the difference between hyperpnoea and hyperventilation?

Answer 9

Hyperpnoea is when minute ventilation increases in proportion to metabolic rate, whereas hyperventilation is when minute ventilation increases more than metabolic rate does

Question 10

What is minute ventilation?

Answer 10

The amount of air that is moved by the lungs in one minute