Anatomy of Chest Wall and Mechanics of Breathing

Question 1

What does Boyle’s law state

Answer 1

The pressure exerted by a gas is inversely proportional to its volume (P^a 1/V).

Question 2

What does Dalton’s law state

Answer 2

The total pressure of a gas mixture is the sum of the pressures of the individual gases

Question 3

What does Charles law state

Answer 3

The volume occupied by a gas is directly related to the absolute temperature (v^a T)

Question 4

What does Henry’s law state

Answer 4

The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid

Question 5

In which direction do gases (singly or in mixtures) move

Answer 5

From areas of high pressure to areas of low pressure

Question 6

How many lobes is the right lung divided into

Answer 6

3

Question 7

How many lobes is the left lung divided into

Answer 7

2

Question 8

Name the right lung lobes

Answer 8

Superior lobe
Middle lobe
Inferiorlobe

Question 9

Name the left lung lobes

Answer 9

Superior lobe

Inferiorlobe

Question 10

What are both lungs enclosed in

Answer 10

Two pleural membranes for each lung

Question 11

What passes through the thorax

Answer 11

Esophagus and aorta between the pleural sacs

Question 12

What is between the surfaces of pleural membranes

Answer 12

An extremely thin layer of intrapleural fluid

Question 13

What is the interior of the thorax covered by

Answer 13

Pleural membranes

Question 14

What does the visceral pleural membrane coat

Answer 14

Outer surface of the lung

Question 15

What does the parietal pleural membrane coat

Answer 15

Inner surface of rib

Question 16

What is found between the visceral and parietal pleural membrane

Answer 16

Pleural fluid

Question 17

How are the lungs bound (‘stuck’) to the rib cage

Answer 17

Through the relationship of the pleural membranes

Question 18

What is pleurisy

Answer 18

Inflammation of the pleura

Question 19

What can the intrapleural pressure be described as in a normal lung at rest

Answer 19

Subatmospheric

Question 20

What does elastic recoil do to the normal lung at rest

Answer 20

Elastic recoil of the chest wall will try to pull the chest wall outward
Elastic recoil of the lung creates an inward pull

Question 21

What is a pneumothorax

Answer 21

Air in the chest wall

Question 22

What occurs in a pneumothorax

Answer 22

Sealed pleural cavity is opened to the atmosphere
Air will flow in
Ribcage will expand slightly
Lung will collapse to an un-stretched size

Question 23

Why does breathing occur

Answer 23

Because the thoracic cavity changes volume based on Boyles law

Question 24

Simplify Boyles law

Answer 24

Increase volume = decrease pressure

Decrease volume = increase pressure

Question 25

What does inspiration use

Answer 25

External intercostal muscles
Diaphragm
Sternocleidomastoids
Scalenes

Question 26

What does expiration use

Answer 26

Passive at rest

Uses internal intercostal and abdominal muscles during severe respiratory load

Question 27

In what state is the diaphragm after relaxed expiration and before inspiration

Answer 27

At rest

Question 28

What does the pump handle motion do

Answer 28

Increase the anterior-posterior dimension of the ribcage

Question 29

What does the bucket handle motion do

Answer 29

Increase the lateral dimension of the rib cage

Question 30

What is asthma

Answer 30

An over-reactive constriction of bronchial smooth muscle

It increases resistance making expiration difficult

Question 31

What occurs during inspiration

Answer 31

The diaphragm contracts to increase thoracic volume and the airways are pulled open by the physical forces of inspiration

Question 32

What occurs during expiration

Answer 32

The diaphragm relaxes to decrease thoracic volume and the airways are compressed by the physical forces of expiration

Question 33

What are the three relevant pressures

Answer 33

Intra-thoracic (Alveolar) Pressure (P A)
Intra-pleural Pressure (P ip)
Transpulmonary pressure (P T)

Question 34

What is intra-thoracic (Alveolar) Pressure (PA)

Answer 34

The pressure inside the thoracic cavity (i.e. pressure inside the lungs)
It can be negative or positive when compared to the atmospheric pressure

Question 35

What is intra-pleural Pressure (Pip)

Answer 35

The pressure inside the pleural cavity

This is always negative in healthy lungs

Question 36

What is transpulmonary pressure (PT)

Answer 36

The difference between the alveolar pressure and intra-pleural pressure
This is always positive in healthy lungs because P ip is always negative (PT = PA – Pip)

Question 37

What is the bulk flow of air between the atmosphere and alveoli proportional to

Answer 37

The difference between the atmospheric and alveolar pressures and inversely proportional to the airway resistance: F = (P atm- P A)/R

Question 38

When does Patm= PA

Answer 38

At the end of an unforced expiration, between breaths

Question 39

Why does P atm= PA

Answer 39

Because no air is flowing

The dimensions of the lungs and thoracic cage are stable as the result of opposing elastic forces

Question 40

What does a transplumonary pressure create when there is a subatmospheric pressure

Answer 40

Pressure that opposes the forces of elastic recoil

Question 41

How is the amount of air that flows into lungs determined

Answer 41

By airway resistance at any given pressure difference between atmosphere and alveoli

Question 42

What is a major determinant of airway resistance

Answer 42

The radii of the airways