Respiration - Mechanics

Question 1

What is oxygen pressure in blood at rest?

Answer 1

PO2 = 100+/-2 mmHg

Question 2

What is carbon dioxide pressure in blood at rest?

Answer 2

PCO2 = 40+/-2 mmHg

Question 3

What is the oxygen exchange at rest?

Answer 3

250ml/min

Question 4

What is carbon dioxide exchange at rest?

Answer 4

200ml/min

Question 5

What is the oxygen exchange and carbon dioxide exchange when walking 3mph?

Answer 5

800ml/min
750ml/min

Question 6

What is the oxygen exchange and carbon dioxide exchange when exercising extremely?

Answer 6

5000ml/min
6000ml/min

Question 7

What is the function of the upper airways?

Answer 7

conduct air into lungs
humidify air
warm air
filter air

Question 8

What is the lining of the upper airways

Answer 8

pseudo-stratified ciliated columnar epithelium

Question 9

What is the value of ventilation at rest?

Answer 9

6-7 L/min

Question 10

How many breathes are taken per min at rest?

Answer 10

12-15 breathes of 500ml

Question 11

What is max value of ventilation?

Answer 11

160 L/min

Question 12

What are max breathes taken per min?

Answer 12

40 breathes of 40L

Question 13

What is cardiac output, bpm and blood per beat during rest?

Answer 13

5L/min, 70bpm, 70ml/beat

Question 14

What is max cardiac output, bpm and blood per beat?

Answer 14

25L/min, 200bpm, 125ml/beat

Question 15

In quiet breathing what process is active and what process is passive?

Answer 15

inspiration = active
expiration = passive

Question 16

What happens during inspiration in quiet breathing?

Answer 16

diaphragm contracts downwards pushing abdominal contents outwards

external intercostal muscles pull ribs upwards and outwards

Question 17

What happens during expiration in quiet breathing?

Answer 17

elastic recoil

Question 18

In strenuous breathing what process is active and what process is passive?

Answer 18

inspiration = active
expiration = active

Question 19

What happens during inspiration in strenuous breathing?

Answer 19

greater contraction of diaphragm and external intercostal muscles

inspiration accessory muscles are activated (sternocleidomastoid, alae nasi, genioglossus)

Question 20

What happens during expiration in strenuous breathing?

Answer 20

abdominal muscles are engaged (internal and external oblique, rectus abdominus, transverse abdominus)

internal intercostal muscles oppose external intercostal muscles pushing ribs down and inwards

Question 21

What happens to the diaphragm during inspiration?

Answer 21

domes flatten as the muscle contracts

Question 22

What are the muscles of inspiration (main + accessory)?

Answer 22

main - diaphragm, external intercostals
accessory - sternocleidomastoid, alae nasi, genioglossus

Question 23

What are the muscles of forced expiration?

Answer 23

internal intercostal, abdominal muscles, (rectus abdominus, transverse abdominus, external/ internal oblique)

Question 24

What do the internal intercostal and abdominal muscles do?

Answer 24

depress ribs

Question 25

What is pleural pressure?

Answer 25

pressure surrounding the lung, within the pleural space. generated by the opposing elastic recoils of the lung and chest wall and the forces generated by respiratory muscles.

Question 26

What is alveolar pressure?

Answer 26

pressure inside of the alveoli

Question 27

What is transpulmonary pressure?

Answer 27

Transpulmonary pressure is the difference between the alveolar pressure and the intrapleural pressure in the pleural cavity.

Question 28

What is the alveolar pressure at the beginning of inspiration?

Answer 28

= barometric

Question 29

What happens to the pleural pressure when muscles contract during inspiration?

Answer 29

becomes more negative

Question 30

What happens when the alveolar volumes increases during inspiration to the alveolar pressure?

Answer 30

becomes negative

Question 31

What is the barometric/atmospheric pressure?

Answer 31

the air pressure outside the body

Question 32

When does inspiration end and therefore flow?

Answer 32

when the alveolar pressure and the barometric pressure are equal

Question 33

What happens at the start of expiration?

Answer 33

thoracic volume decreases and pleural and transpulmonary values return to pre-inspiration

Question 34

When does air flow out of lungs?

Answer 34

when alveolar pressure is higher than barometric

Question 35

Why does air enter and leave the lungs?

Answer 35

air travels from high pressure to low pressure

Question 36

Describe volume changes and pressure during inspiration

Answer 36

1. Beginning of inspiration - alveolar P = barometric P 2. Muscles contract, increasing thoracic volume - pleural P becomes more negative, increase in transpulmonary P 3. Lungs expand and alveolar volume increases, air enters into alveoli from a high to low concentration - alveolar P becomes negative (less than barometric) 4. End inspiration, muscles stop contracting thorax stops expanding -alveolar P = barometric P

Question 37

Describe volume changes and pressure during expiration?

Answer 37

1. Beginning of expiration, thoracic volume decreases, pleural P and transpulmonary P return to pre-inspiration values 2. thorax and lungs recoil, air in alveoli becomes compressed and exits - alveolar P becomes higher than barometric P

Question 38

What's the difference of depth of diaphragm contraction in relaxed vs strenuous breathing?

Answer 38

1cm relaxed up to 10cm strenuous

Question 39

How much oxygen per litre breathed in healthy relaxed lungs?

Answer 39

1ml (2% of resting energy expenditure)

Question 40

What breathing is more efficient and less turbulent?

Answer 40

low level breathing (less muscles used)

Question 41

What is the functional residual capacity (FRC)?

Answer 41

Volume of air in lungs at the end of expiration during quiet breathing ERV + residual volume Outward and inward forces and equal and chest is relaxed

Question 42

Why does the FRC decrease in patients with neuromuscular disorders?

Answer 42

chest muscles are weaker therefore lung elastic recoil is greater and forces are unbalanced

Question 43

What is the tidal volume (TV)?

Answer 43

volume during relaxed breathing usually 500ml

Question 44

What is the inspiratory reserve volume (IRV)?

Answer 44

forceful inhalation 3300ml

Question 45

What is the expiratory reserve volume (ERV)?

Answer 45

forceful exhalation 1000ml

Question 46

What is residual volume?

Answer 46

air present we cannot exhale 1200ml

Question 47

What is the vital capacity?

Answer 47

the TV + IRV + ERV

Question 48

What is the total lung capaccity in males vs females?

Answer 48

males = 6000ml females = 4200ml

Question 49

What is the FVC?

Answer 49

forced vital capacity - similar to VC however it is the maximum air inhaled and exhaled