Respiratory physiology 3

Question 1

What is tidal breathing?

Answer 1

Normal relaxed breathing. 500 mL.

Question 2

What is inspiratory reserve volume IRV ?

Answer 2

Volume that we can breath in on the top on tidal volume. It is 3000 mL.

Question 3

What is expiratory reserve volume ERV?

Answer 3

Volume that we can breath out on the top of normal expiration. It is 1100 mL.

Question 4

What is vital capacity VC?

Answer 4

Maximum amount of air that can be shifted in one breath, tidal breathing + IRV + ERV. It is equal to 4600 mL.

Question 5

What is residual volume RV?

Answer 5

The amount of air that can’t be exhaled from lungs. It is equal to 1200 mL.

Question 6

What is functional residual capacity FRC?

Answer 6

The amount of air left in the lungs after normal tidal breathing. RV +ERV It is equal to 2300 mL.

Question 7

What is total lung capacity?

Answer 7

The amount of air that can be in the lungs, VC + RV. It is equal to 5800 mL

Question 8

What is the role of residual volume?

Answer 8

Prevents alveoli from collapsing and enables gas exchange to occur all the time.

Question 9

On which lung values has anaesthetic impact?

Answer 9

On functional residual capacity. It also prevents bronchioles from collapsing.

Question 10

Why does lung function with age deteriorate?

Answer 10

As we age our muscles get weaker and the lungs become less elastic.

Question 11

Why is the first breath the hardest one?

Answer 11

Because babies need to inflate the alveoli and fill the residual volume.

Question 12

What is anatomical dead space?

Answer 12

The air in conducting airways, it is usually 150 mL.

Question 13

How much of fresh air reaches the alveoli?

Answer 13

Only 350 mL, 150 mL stays in the conducting airway. Therefore only 70% is available for gas exchange.

Question 14

What is stale air?

Answer 14

The alveolar air that fills the anatomical dead space on expiration.

Question 15

What is ventilation?

Answer 15

Movement of air in and out of lungs.

Question 16

What is pulmonary ventilation?

Answer 16

The total amount of air moved, it is product of tidal volume and respiratory frequency.

Question 17

What is alveolar ventilation?

Answer 17

Fresh air that reaches the alveoli, tidal volume - anatomical dead space x respiratory frequency.

Question 18

What has bigger impact in the alveolar ventilation, rate or depth of breathing?

Answer 18

Depth of breathing.

Question 19

What happens in hypoventilation?

Answer 19

Rapid and shallow breathing, PO2 falls to about 30 mm Hg, and PCO2 raises to about 100 mmHg.

Question 20

What happens in hyperventilation?

Answer 20

Rapid and deep breathing, PO2 raises to about 120 mm Hg, PCO2 falls to about 20 mmHg

Question 21

Why is alveolar partial pressure of O2 different from atmospheric?

Answer 21

This is due to the residual volume and dead space that dilute the oxygen, also as we breath in the air gets humidified and this changes O2 solubility. In addition there is content gas exchange and so the alveolar PO2 is in equilibrium with arterial PO2.

Question 22

What is the partial pressure of O2 and CO2 in alveoli ?

Answer 22

PO2 = 100 mm Hg, PCO2 = 40 mmHG