Dynamic Mechanics of Breathing

Question 1

What two zones is the lung split into?

Answer 1

Conducting zone-branching

Transit and Respiratory Zone- Alveoli and sacs

Question 2

Why is the lungs not that effective?

Answer 2

Gas has to move in and out through the same set of tubes that deliver gas to the alveolar
Provides resistance

Question 3

Even though the tubes are small and generatate a lot of resistance. What can be said about the cumalative resistance?

Answer 3

Its lower due to the amount of tubes

Question 4

Whatv are the factors that determine resistance?

Answer 4

Lung volume and branching
Bronchiolar smooth muscle tone
Density and viscosity of gas

Question 5

What is bronchiolar smooth muscle?

Answer 5

Smooth muscle that lines upper airway and influences tube radius.
Consequences for altering gas flow in the airways

Question 6

How is the bronchiolar tibe radius decreased?

Answer 6

• Parasympathetic activity
• Ach neurotransmission
• Irritants (smoke, allergens)
• Decreased alveolar PCO2

Question 7

How is the bronchiolar tube radius increased?

Answer 7

• Sympathetic activity
• Pulmonary stretch
• NAdr (neutral to week)
• Adr

Question 8

What diseases are linked to resistance?

Answer 8

Asthma COPD

Question 9

Describe an asthmatic airway

Answer 9

Narrowed airway

Increased airway in smooth muscle

Question 10

Describe an asthmatic airway during an asthma attack

Answer 10

Constricted airway

Contracted airway in smooth muscle

Question 11

Describe what happens during an asthma attack

Answer 11

Allergic inflammation of the airways
Hyper-reactivity of airway smooth muscle contraction
Bronchial smooth muscle thickening

Question 12

What does contraction of parabronchial smooth muscle do?

Answer 12

Raises upper airway resistance

Question 13

What raises the convection of the lung?

Answer 13

Deep and fast breathing

Question 14

Describe the workings of an asthmatic lung compared to a healthy lung

Answer 14

• Oxygen slows to its molecular velocity in the lung much quicker than a regular lung causing poor gas exchange
• Gas fails to penetrate to distal regions of respiratory zone causing alveolar pCO2 to rise
• Lung ceases to oxygenate Hb efficiently due to reversal of proper alveolar Bohr and haldnae effects

Question 15

Where does the asthmatic wheeze come from?

Answer 15

Laminar flow

Complicated by dichotomous branching- Eddies and turbulence

Question 16

How is airway resistance measured?

Answer 16

Whole body Plethysmography

Question 17

During inhalation, what happens to airway resistance as gas flow and lung volume increase?

Answer 17

Falls

Question 18

During exhalation, the resistance of the upper airways helps to keep what?

Answer 18

Pressure high to maximise gas movement out of alveoli

Question 19

What does exhalation work against?

Answer 19

Smooth muscle contraction and upper airway resistance

Question 20

What is COPD characteriased by?

Answer 20

Increased resistance to air flow

Might be caused by mucus in the airways

Question 21

Describe the ‘blue puffer’ in patients with COPD

Answer 21

1)Alveoli destruction
2)Reduced surface area
3)Reduced elasticity
Patient oxygenation is poor (hence blue)

Question 22

Why would patients with COPD breath with pursed lips?

Answer 22

Maintaining airway pressure high all the way through conducting zone through lung
Using dynmaic compression to raise airway pressure that allows to clear the lung of gas from lower airways
Energetically exhausting

Question 23

What is meant by work of breathing?

Answer 23

To overcome elastic and non elastic resistances

Question 24

What is the work of inspiration?

Answer 24

Energy input required to overcome elastic component and energy input required to overcome surface tension

Question 25

What is meant by work of expiration?

Answer 25

Energy input to overcome airway and tissue resistance

Question 26

Where is the energy expended during panting breathing pattern?

Answer 26

Inhalation- Surface tension

Exhalation- Dynamic compression upper airway resistance

Question 27

Where is the energy expended during deep breathing (athlete before race)?

Answer 27

Inhalation- Elastic component