Lung volumes and ventilation

Question 1

what is tidal volume and what is normal volume?

Answer 1

volume of air inspired during quiet respiration
400-500mls

Question 2

what is inspiratory reserve volume and what is normal volume?

Answer 2

volume of air inspired from tidal volume to maximal inspiration
up to 3L

Question 3

what is expiratory reserve volume and what is normal volume?

Answer 3

air expelled with forced expiration
up to 1.5L

Question 4

what is residual volume and what is normal volume?

Answer 4

amount of air left in lungs which cannot be expelled
1.5L

Question 5

what is functional residual capacity?

Answer 5

lung volume at the end of normal quiet expiration
ERV + RV

Question 6

what is vital capacity?

Answer 6

volume of air from maximal inspiration to maximal expiration
IRV + VT+ ERV

Question 7

what is total lung capacity?

Answer 7

volume from maximal inspiration to residual volume
IRV + VT + ERV + RV

Question 8

what affects lung volumes?

Answer 8

body size
age (reduction in 70+)
gender
muscle training (inspiratory muscles)
disease (smoking makes airways narrow)

Question 9

why does residual volume increase as we get older?

Answer 9

lung tissues lose elasticity and dont recoil as much

Question 10

what is the clinical relevance of functional residual capacity?

Answer 10

necessary to keep the lungs partially inflated at the end of expiration. this makes the lungs more compliant (easier to inflate)

Question 11

what is closing volume?

Answer 11

the critical amount of FRC needed to keep distal alveoli and small airways open

Question 12

what happens when FRC falls below CV?

Answer 12

the distal airways and small airways collapse which leads to an increased work of breathing

Question 13

what vital capacity is required to be able to maintain spontaneous, unsupported ventilation?

Answer 13

1L

Question 14

what is FEV1?

Answer 14

forced expiratory volume in first second of expiration

Question 15

what is FVC?

Answer 15

forced vital capacity

Question 16

what is FEV1/FVC%?

Answer 16

of the total volume expired, what % is expired in the first second

Question 17

what is flow volume loop?

Answer 17

forced inspiratory and expiratory flow from full expiration to full inspiration

Question 18

what is obstructive disease?

Answer 18

airway narrowing, problem with expiration

Question 19

what is restrictive disease?

Answer 19

problem with lung or chest wall expansion, problem with inspiration

Question 20

what is normal respiratory frequency?

Answer 20

12bpm

Question 21

what is minute ventilation?

Answer 21

the volume of air entering the lung per minute
respiratory frequency + average volume

Question 22

what is dead space?

Answer 22

the part of the tidal volume not involved in gas exchange

Question 23

what are the two types of dead space?

Answer 23

anatomical dead space
alveolar dead space

Question 24

what is physiological dead space?

Answer 24

anatomical dead space + alveolar dead space
total dead space
sum of all parts of tiday volume which does not participate in gas exchange

Question 25

how does air move in the conducting zone?

Answer 25

via convection

Question 26

how does air move in the respiratory zone?

Answer 26

via diffusion

Question 27

what is anatomical dead space?

Answer 27

air that sits in the bronchial tree that isnt used in gas exchange

Question 28

how much anatomical dead space is there normally?

Answer 28

with each tidal volume, 150mls remains in conducting zone up to terminal branches and is not used in gas exchange. the full tidal volume of 500mls is expired

Question 29

what is alveolar dead space?

Answer 29

inspiratory gas reaching alveoli but is unable to participate in gas exchange due to insufficient blood supply A V/Q mismatch, where there is air in the alveoli but no perfusion through the adjacent capillary (wasted ventilation)

Question 30

how much alveolar dead space do normal, healthy individuals have?

Answer 30

almost 0

Question 31

what is VQ matching?

Answer 31

air (V) in the alveoli and blood (Q) running through the capillary adjacent to it

Question 32

what is a shunt?

Answer 32

V/Q mismatch where there is low/no air in the alveoli but it is still being perfused (wasted perfusion)

Question 33

what is alveolar ventilation?

Answer 33

the amount of minute ventilation reaching respiratory zone used in gas exchange tidal volume - anatomical dead space ~350ml / breath

Question 34

how can you increase alveolar ventilation?

Answer 34

increase respiratory frequency (bpm) (quicker breaths) increase tidal volume (deeper breaths)

Question 35

is it more efficient to increase respiratory frequency or tidal volume if you want to increase alveolar ventilation?

Answer 35

tidal volume smaller proportion of anatomical dead space

Question 36

what is hypoventilation and what happens to carbon dioxide levels?

Answer 36

not breathing enough CO2 levels increase

Question 37

what is hyperventilation and what happens to CO2 levels?

Answer 37

breathing out more CO2 than normal, CO2 levels reduce

Question 38

why might someone hypoventilate?

Answer 38

infection sputum plug atelectasis COPD asthma pain reduced respiratory drive / consciousness

Question 39

why might someone hyperventilate?

Answer 39

anxiety/fear metabolic disease airway obstruction parenchymal lung disease altitude

Question 40

what factors affect arterial oxygen content?

Answer 40

ventilatory pattern V/Q matching Hb content of blood Hb affinity for oxygen atmospheric pressure O2 specific characteristics of alveolar membrane

Question 41

how does Hb content of blood affect O2 content?

Answer 41

Hb carries 4 oxygen molecules anaemic people dont have enough Hb and so not enough O2

Question 42

how does Hb affinity for oxygen affect O2 content of blood?

Answer 42

some diseases mean Hb cant combine effectively with oxygen e.g. sickle cell anaemia

Question 43

how does atmospheric pressure affect O2 content in blood?

Answer 43

at altitude, the concentration of O2 is reduced