Applied Lung Physiology

Question 1

Is it easy or difficult to understand and quantifying resistance in conduction zone?

Answer 1

Difficult

Question 2

Why is it difficult to measure airway resistance in conduction zone?

Answer 2

• Branching of air ways, narrowing of airways, dispensable, compressible leads to DYNAMIC resistance
• Air flow changes as well (laminar, turbulent and transitional)

Question 3

What is airway resistance?

Answer 3

Presuming the air flows through a rigid, smooth bored tube governed by Poiseuille’s law

Question 4

What is the airway resistance equation?

Answer 4

Change in pressure = Airflow (V) x Resistance (R1)

Question 5

What is Poiseuille’s law?

Answer 5

Resistance is directional proportional to viscosity of fluid and the length of tube and inversely proportional to the forth power of the radius of the tube

Question 6

If R^4, what would the resistance be if the radius reduced by half?

Answer 6

16

Question 7

What conditions are associated with changes in resistance?

Answer 7

-Asthma, bronchitis, croup

Question 8

What is important to the resistance of airflow?

Answer 8

Radius

Question 9

Describe bronchial smooth muscle dilation:

Answer 9

1. ACH binds to receptor
2. Phospholipase C becomes active - causing production of IP3
3. IP3 binds to specific receptors (e.g sarcoplasmic reticulum)
4. Ca 2+ is released into cytosol
5. Alongside couple protein, Ca2+ is released by L-type channel where DAG contributes to Ca2+ sensitisation and rho A kinase active inhibits MLCPK
6. Ca2+ and calmodulin binds to form Ca2+ calmodulin complex
7. Thus complex helps activate MLCK
8. Conversion between ATP to ADP and Pi with the help of MLCK
9. Phosphorylation of myosin head activates - allowing a cross-bridge formation with actin filaments
10. MLCP removes phosphate group from active myosin head with associated MLC to become inactive
11. Ca2+/Na+ antiporter pumps out Ca2+ to ensure concentration is bellow threshold

Question 10

What is bronchial smooth muscle dilation?

Answer 10

Number of triggers cause inhibition of contraction in bronchi

Question 11

What is type I asthma?

Answer 11

Hypersensitivity

• Allergic or immediate hypersensitivity
• Develops IgE antibodies in response to harmless antigens

Question 12

How do you make allergen from IgE?

Answer 12

Adaptive immune response by B cells that form plasma cells

Question 13

What do IgE do in type I asthma?

Answer 13

Enters circulation and binds to mast cells in tissue

Question 14

What does cross-linking causes mast cells to do?

Answer 14

Degranulate and release:

• Vasoreactive amines- Histamine
• Cytokines/chemokines
• Leukotrienes

Question 15

How do you measure compliance?

Answer 15

Measure as volume per unit pressure change

Question 16

What are the units form compliance?

Answer 16

mL cmH20^-1

Question 17

Does emphysema have a higher or lower compliance than compliance in normal people?

Answer 17

Higher

Question 18

Does fibrosis have a higher or lower compliance than compliance in normal people?

Answer 18

Lower

Question 19

How does emphysema occur?

Answer 19

• Destruction of alveolar walls = large air spaces not cleared of air on exhalation
• Decrease in elastic fibres = decrease in elastic recoil
• Decrease in gas exchange = decrease in O2 diffusion = decrease O2 levels in blood

Question 20

What is the symptoms of emphysema?

Answer 20

• Barrel chest

- Breathlessness even in mild exercise

Question 21

What is COPD?

Answer 21

Chronic Obstructive Pulmonary Disease

Question 22

What are two principles causes of COPD?

Answer 22

Emphysema and chronic bronchitis

Question 23

What is surfactant?

Answer 23

Lipoprotein secreted by type II alveolar cells

Question 24

What does surfactant liquid fit linen?

Answer 24

Alveoli

Question 25

What does surfactant affect surface tension?

Answer 25

Alveoli

Question 26

If there is lower surface tension what happens in relation to compliance and breathing?

Answer 26

• Increase compliance

- Improves work of breathing

Question 27

What is the average ventilation of the alveoli?

Answer 27

4-6 L/min

Question 28

What is the average of pulmonary flow?

Answer 28

4-6 L/min

Question 29

What is average ventilation/perfusion matching?

Answer 29

0.8-1.2

Question 30

What must you due to regional difference in ventilation and perfusion?

Answer 30

Match ventilation and perfusion at the alveolar-capillary level

Question 31

At the start of inspiration, alveoli at base of lungs are smaller what does mean it is capable of?

Answer 31

More capacity to expand

-Ventilation in areas are greater over the whole breathing cycle

Question 32

What does V stand for?

Answer 32

Ventilation

Question 33

What does Q stand for?

Answer 33

Perfusion

Question 34

What happens when perfusion pressure falls above level of heart but increase below it?

Answer 34

Blood flow increases steadily from apex to base of lungs

Question 35

Is ventilation and perfusion directly or inversely proportional?

Answer 35

Directly proportional

Question 36

What are the problems in ventilation-perfusion matching?

Answer 36

Affect O2 and CO2 transfers

Question 37

If there is shunt in the way what does that affect relating to ventilation?

Answer 37

Pulmonary arterial blood from this area is not oxygenated

Question 38

What is alveolar dead-space?

Answer 38

• No perfusion

- Alveolar gas is the same as room air, containing no CO2