CBT2 Ventilation and gas exchange Flashcards Preview

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Flashcards in CBT2 Ventilation and gas exchange Deck (119)
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1

Define Tidal volume (TV or V small T)

The volume of air inspired and expired during regular breathing (i.e. gentle normal breathing not deep breathing)

2

Define Inspiratory reserve volume (IRV)

The volume of air that can be inspired after a tidal inspiration

3

Define Expiratory reserve volume (ERV)

The volume of air that can be expired after a tidal expiration

4

Define Residual volume (RV)

The volume of air that cannot be emptied from the lungs, no matter how hard you expire. This is fixed because of the lung-chest wall interface

5

How do you calculate the total lung capacity? (TLC)

RV + IRV + TV + ERV

6

How do you calculate the functional residual capacity (FRC)

RV + IRV. The volume of air in the lungs following a tidal expiration at rest. This capacity represents the “default” volume of the lungs, when the lung recoil (inwards) and chest recoil (outwards) are in equilibrium

7

How do you calculate inspiratory capacity (IC)

TV + IRV. The maximum volume of air the lungs can draw in from the equilibrium FRC point

8

How do you calculate vital capacity (VC)

TLC – RV; or, TV + IRV + ERV. The volume of air between the maximum and minimum achievable volumes (range)

9

What factors affect all the different breathing and lung volumes?

Height is the most influential, but others include:
- age
- genetics
- aerobic
- fitness
- disease
- developmental exposure to altitude

10

What does dead space describe? (V small D)

Generic term that describes parts of the airways that do not participate in gas exchange (e.g. conducting and respiratory airways)

11

What are the three types of dead space?

1) Anatomical dead space
2) Alveolar dead space
3) Physiological dead space

12

Describe Anatomical dead space

This includes the entirety of the conducting airways and the upper respiratory tract (oral/nasal cavity, pharynx and larynx). This value cannot be measured using standard spirometry. It requires a dilution test with a known volume of inert gas (e.g. helium)

13

Describe Alveolar dead space

This includes respiratory tissues unable to participate in gas exchange, usually due to an absent or inadequate blood flow. In healthy individuals, this volume is effectively zero

14

Describe Physiological dead space

This is the sum of anatomical and alveolar dead space volumes

15

How many generations are there in the conducting zone?

16 generations

16

Typically how many ml are there in the anatomical dead space?

150ml in adults at FRC

17

What are non-perfused parenchyma?

Alveoli without a blood supply

18

How many generations is the respiratory zone?

7 generations

19

How many ml is the respiratory zone in adults? (referred to as alveolar ventilation)

350ml

20

What is the amount of air moving in and out of the lungs per minute referred to?

pulmonary ventilation (V small E)

21

How is pulmonary ventilation calculated?

TV x breathing frequency

22

What is the primary function of breathing?

Ventilation of the alveolar tissue

23

What is alveolar ventilation?

The amount of air per minute reaching the gas exchange surface

24

How do you calculate alveolar ventilation during tidal breathing?

It is equal to the difference between tidal volume and dead space multiplied by breathing frequency (V small alv = ((VT - VD) x Rf). 

25

Typically, for every generation further down the airway there is a divergence in the path associated with a _____ decrease in the pressure and velocity of airflow.

50%

26

At rest, how are the mechanical forces of the lungs balanced?

At equilibrium

27

How can the balance of mechanical forces be distorted, in order to stimulate ventilation?

Increasing pressure outside of the lung, or decreasing pressure inside the lung

28

What is positive-pressure breathing?

Increasing pressure outside of the lung (e.g. a patient on a ventilator)

29

Explain negative-pressure breathing, i.e. inhalation under normal conditions

The respiratory muscles decreases intrathoracic pressure (diaphragm contracts downward towards the abdomen and the external intercostal muscles pull the ribcage outwards and upwards) by creating a partial vacuum; the lung as an elastic expandable tissue stretches to fill the space which sucks air in from the outside the body to normalise the pressure.

30

At rest, with no activation of the respiratory muscles, the volume of the lungs is equal to the ________

functional residual capacity (FRC)