Gas Exchange - Mammals

Question 1

What are the two types of airways in mammalian lungs?

Answer 1

Conducting and respiratory

Question 2

What are conducting airways? What structures are conducting airways?

Answer 2

Sections of the respiratory tract where no gas exchange occurs. Include trachea, bronchi, and terminal bronchioles

Question 3

What are respiratory airways? What structures are respiratory airways?

Answer 3

Sections of the respiratory tract where gas exchange occurs. Include respiratory bronchioles, alveolar ducts, and alveolar sacs

Question 4

What muscle controls breathing?

Answer 4

Diaphragm

Question 5

What is the structure of the alveoli?

Answer 5

Polygonal, flattened walls, wrapped in capillaries and suspended in collagenous matrix

Question 6

Why is diffusion between the blood and alveoli so efficient?

Answer 6

Distance is very short and the walls of both the alveoli and capillaries

Question 7

Does only diffusion move air around in the lungs?

Answer 7

No, bulk flow via convection is used first to move large amounts of air

Question 8

What is important about the air in the alveoli?

Answer 8

There is always air in there and it is motionless, so oxygen needs to diffuse across the final distance

Question 9

Why is it critical that the alveoli always have air in them?

Answer 9

Prevent collapse

Question 10

What are the 3 types of cells in the alveoli?

Answer 10

Type 1, type 2 and macrophages

Question 11

What do type 1 cells do?

Answer 11

Gas exchange

Question 12

What do type 2 cells do?

Answer 12

Secrete surfactants

Question 13

What do macrophages do?

Answer 13

Destroy pathogens

Question 14

What does the surfactant do?

Answer 14

Maintains surface tension of water droplets in the alveoli and prevents the alveoli from collapsing. Decreases surface tension of a liquid and decreases the recoil tendency

Question 15

What happens to a smaller alveolus if there’s no surfactant?

Answer 15

It collapses into a larger one

Question 16

Are all alveoli the same size?

Answer 16

No, some are larger than others

Question 17

How much surfactant will be in a small alveolus compared to a larger one?

Answer 17

More in the smaller one to prevent collapse into the larger one

Question 18

What is the surfactant made of?

Answer 18

Amphipathic lipoproteins

Question 19

What is recoil tendency?

Answer 19

The elastic recoil of the alveoli that aids in exhalation

Question 20

What are the two things that help with the recoil tendency of the alveoli?

Answer 20

Water drops and surfactant

Question 21

What is the pleural sac?

Answer 21

Small fluid filled sac between the lung and chest wall

Question 22

What is atelectasis?

Answer 22

Collapse of the alveoli

Question 23

What is the pressure inside the pleural sac?

Answer 23

756 mmHg

Question 24

Why is it so important that the intrapleural pressure is less than the atmospheric pressure?

Answer 24

Prevents alveolar collapse and maintains integrity of the lungs

Question 25

Why does the pleural sac need to be filled with fluid?

Answer 25

Allows the walls of the sac to slide past each other during respiration

Question 26

What is one of the major factors that stretches the lungs in the thoracic cavity throughout ventilation to prevent collapse of the lungs?

Answer 26

Cohesiveness of water

Question 27

What is pneumothorax?

Answer 27

Collapsed lungs, the physical penetration of the pleural sac from injury

Question 28

What are the two types of pneumothorax?

Answer 28

Traumatic and spontaneous

Question 29

What is traumatic pneumothorax?

Answer 29

Chest wall is punctured

Question 30

What is spontaneous pneumothorax?

Answer 30

Punctured lung

Question 31

What are the two phases of tidal ventilation?

Answer 31

Inspiration and expiration

Question 32

What is happening to the diaphragm, the intercostal muscles, and the pleural sac during inspiration?

Answer 32

Diaphragm and intercostal muscles contract and expand the thoracic cavity, and the expansion pulls on the outer layer of the pleural sac and creates the negative pressure

Question 33

What happens during expiration?

Answer 33

Diaphragm and intercostal muscles relax, abdominal muscles contract

Question 34

What is the transmural pressure?

Answer 34

The difference between the intrapleural pressure and the intra-alveolar pressure

Question 35

How does the transmural pressure change during inspiration and expiration?

Answer 35

Increases during inspiration and decreases during expiration

Question 36

Why is transmural pressure important?

Answer 36

Need to stretch the lungs in the thoracic cavity throughout the ventilation cycle to prevent collapsing during expiration

Question 37

How do we measure transmural pressure?

Answer 37

A spirometer

Question 38

What is tidal volume?

Answer 38

The total amount of air moved by one ventilatory cycle (Vt)

Question 39

What is inspiratory reserve volume?

Answer 39

The maximum amount of air able to be inhaled

Question 40

What is expiratory reserve volume?

Answer 40

The maximum amount of air able to be expired

Question 41

What is residual volume?

Answer 41

The amount of air that is always in the lungs

Question 42

What is vital capacity?

Answer 42

The sum of the tidal volume, inspiratory reserve volume, and expiratory reserve volume

Question 43

What respiratory adaptation is seen in animals with long necks?

Answer 43

Increase tidal volume to compensate for additional dead space

Question 44

What is the difference between respiratory minute volume and alveolar minute volume?

Answer 44

Alveolar minute volume takes the dead space into account

Question 45

What happens to respiratory minute volume and alveolar minute volume during exercise?

Answer 45

They both increase

Question 46

How are cardiac output and ventilation related?

Answer 46

Both increase proportionally, the ratio stays at about 1

Question 47

What is the prefusion ratio?

Answer 47

Cardiac output

Question 48

What are the two forces that keep the thoracic wall and lungs in close application?***

Answer 48

Cohesiveness of water | Transmural pressure gradients