L23 Respiration - Movement Of Air

Question 1

What is compliance?

Answer 1

Measure of elasticity

Question 2

How would you calculate compliance?

Answer 2

Change in volume / change in pressure

Question 3

What does it mean to have low/high compliance?

Answer 3

Low compliance - more work required to inspire (less flexible)

High compliance - often also involves more difficulty expiring

Question 4

What are the two major components contributing to the elastic recoil of the lungs?

Answer 4

Anatomical component (elastic nature of cells) and the surface tension generated at air-fluid interface

Question 5

How does surface tension develop within the lungs?

Question 6

What is Laplace’s equation?

Answer 6

P=(2T/r)

Question 7

What would the pressure be in a small alveoli compared to a larger alveoli ?

Answer 7

Small alveoli would have a larger pressure according to Laplace’s law

Air will flow from smaller alveoli to larger, leading to their collapse

Question 8

What is the role of surfactant for alveoli cells ?

Answer 8

It prevents the smaller alveoli to collapse

Question 9

How is surfactant in alveoli’s produced ?

Answer 9

They are produced by type II pneumocyte. Surfactant is composed of a number of lipids and proteins

Question 10

How are all the lung volumes measured?

Answer 10

With the exception of residual lung volume, all the other lung volumes are measured by a spirometer

Question 11

What is anatomical dead space?

Answer 11

It’s the volume of the conducting airways that does not participate in gas exchange (doesn’t come into contact with the alveoli)

Question 12

Why does anatomical dead space exist ?

Answer 12

The conducting airways are necessary to transport air to the alveoli, but they don’t have the specialised structures for gas exchange
. It allows for rapid and efficient delivery of air to the alveoli

Question 13

What is physiological dead space?

Answer 13

Physiological dead space is the volume of air that is inhaled but does not participate in gas exchange, like anatomical dead space, physiological dead space includes both the anatomical dead space and the alveolar dead space

Question 14

How would you calculate the physiological dead space?

Answer 14

Conducting zone + non - functional areas of respiratory zone

Question 15

What is IRV and ERV?

Answer 15

IRV - inspiratory reserve volume. Additional volume of air that can be inhaled forcefully after a normal inhalation

ERV - Expiratory reserve volume. Additional volume of air that can be forcefully exhaled after a normal exhalation

Question 16

What is tidal volume?

Answer 16

Breathing in any level of activity

Question 17

What happens when the tidal volume increases?

Answer 17

There is a decrease in the inspiratory and expiratory volume.

Question 18

How is residual volume calculated?

Answer 18

Using a simple spirometer when expiration makes the bell of the spirometer move up recording the residual volume.

Question 19

What is poiseuille’s law in context to resistance of flow?

Answer 19

Airway resistance is proportional to gas viscosity and the lenght of the tube but is inversely proportional to the fourth power of the radius.

Question 20

Equation of poiseuille’s law?

Answer 20

R = (8/pie) * (nl/r^4).

Question 21

What is the total airway resistance in a normal individual?

Answer 21

1.5cm H2O .s.litres-1

Question 22

Which airways have the series resistance and which has the parralel resistance? (Diameter)

Answer 22

Series resistance - Larger
Parallel resistance - Smaller

Question 23

How is series resistance calculated?

Answer 23

Rt = R1+R2+R3+…

Question 24

How is parallel resistance calculated?

Answer 24

1/Rt = 1/R1 + 1/R2 + …

Question 25

How is the ANS involved in control of bronchial smooth muscles?

Answer 25

1. Parasympathetic - Acetylcholine is released from the vagus, acts on muscarinic receptors leading to constriction.
2. Sympathetic - Release of norepinephrine from nerves

Question 26

What 3 factors impact airway resistance?

Answer 26

Airway diameter: increased mucus secretion will effectively reduce airway diameter- increase resistance
Oedema- increased fluid retention in the lung tissue will cause swelling and narrowing of the airways - increased resistance
Airway collapse - for example during forced expiration, narrows airway, increased resistance