Ventilation and compliance

Question 1

Describe the anatomical dead space and its volume

Answer 1

Volume is 150mL and its the volume of has occupied by conducting airways and this gas is not available for exchange

Question 2

What is average value for tidal volume?

Answer 2

500mL

Question 3

What is inspiratory reserve volume?

Answer 3

3000mL

Question 4

What is expiratory reserve volume?

Answer 4

1100mL

Question 5

What is functional residual capacity and why is it important?

Answer 5

capacity is the air left after passive expiration and includes the expiratory reserve volume and air in alveoli.

Need air in alveoli to allow gas exchange and prevent alveoli from collapsing

Question 6

Describe the two kinds of ventilation

Answer 6

Pulmonary ventilation = total air movement in and out of lungs

Alveolar ventilation = fresh* air getting to alveoli and therefore available for gas exchange

Both measured in L/min

Question 7

Describe how one could hypo or hyper ventilate

Answer 7

50% dead space takes up mr anxious breaths so that’s why he isn’t the highest alveolar ventilation
(If breathing is shallow, then breathing fast can lead to hypoventilation)

Therefore, Mr anxious is hypoventilation whilst mrs chill is hyperventialttion

Question 8

Describe daltons laws

Answer 8

Dalton’s Law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases.

Question 9

What is partial pressure?

Answer 9

The pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture

Eg:
Atmospheric Pressure = 760mmHg (101kPa)
Pressure of air we breathe therefore = 760mmHg
21% of air we breath = O2
Partial pressure of O2 in air we breath = 21% x 760mmHg
= 160mmHg (21kPa)

Question 10

Does partial pressure increase or decrease with increasing gas?

Answer 10

All gas molecules exert same pressure, so partial pressure increases with increasing [gas]mixture

Question 11

What is normal ventilation value?

Answer 11

4.2L/min

Question 12

Why is the partial pressure in the lungs 100 and not 160 like in the air?

Answer 12

100 alveoli
160 = atmosphere

Partial pressure breathed in initially is 160 but then turns to 100

Water vapour saturates the air that is breathed in so water vapour pressure is contributed. CO2 and deadspace is also effecting the pressure of the air inside lungs.

Question 13

What happens to Po2 and Pco2 during hyper ventilation?

Answer 13

During hyper-ventilation (increased alveolar ventilation) PO2 rises to about 120 mm Hg and PCO2 falls to about 20 mmHg.

Question 14

What happens to Po2 and Pco2 during hypo ventilation?

Answer 14

During hypo-ventilation (decreased alveolar ventilation) PO2 falls to 30 mmHg and PCO2 rises to 100 mmHg.

Question 15

What happens to Po2 and Pco2 during hyper ventilation?

Answer 15

During hyper-ventilation (increased alveolar ventilation) PO2 rises to about 120 mm Hg and PCO2 falls to about 20 mmHg.

Question 16

What is the role of surfactant?

Answer 16

Produced by type 2 alveolar cells and reduces surface tension on the alveolar surface membrane thus reducing tendency for alveoli to collapse.

Question 17

Define compliance, high and low

Answer 17

change in volume relative to change in pressure
It represents sustainability not elasticity

HIGH COMPLIANCE = large increase in lung volume for small decrease in ip pressure
LOW COMPLIANCE = small increase in lung volume for large decrease in ip pressure

Question 18

What is emphysema?

Answer 18

Loss of elastic tissue means expiration requires effort

Question 19

What is fibrosis?

Answer 19

inert fibrous tissue means effort of inspiration increases

Question 20

What is obstructive lung disease and restrictive?

Answer 20

Obstructive - obstruction of air, especially on expiration. Increased airway resistance

Restrictive = restriction of the lung expansion. Loss of lung compliance and fibrosis, oedema, pneumothroax and infant respiratory distress syndrome.

Question 21

Give to examples of 2 COPD

obstructive

Answer 21

Chronic bronchitis - Inflammation of the bronchi

Emphysema -Destruction of the alveoli, loss of elasticity

Question 22

Talk about the 5 factors in restrictive lung disorders

Answer 22

1. Loss of lung compliance: stiff lung and incomplete lung expansion
2. Fibrosis: foration or development of excess fibrous connective tissue
3. Infant respiratory distress syndrome: insufficient surfactant production
4. Oedema
5. Pneumothorax

Question 23

What is spirometry?

Answer 23

Used to measure lung function

Static - where only consideration made is the volume exhaled

Dynamic - where the time taken to exhale a certain volume is what is being measured

Question 24

What can the spirometry measure?

Answer 24

Tidal volume, inspiratory reserve volume, expiratory reserve volume, inspiratory capacity and vital capacity

Question 25

What are FEV1/FVC normal values?

Answer 25

Forced expiratory volume in 1 second fit, healthy, young adult males: 4.0L Forced vital capacity fit, healthy, young adult males: 5.0L FEV1/FVC = 80%

Question 26

What are limitation of the FEV1/FVC ratio?

Answer 26

Obstructive: both FEV and FVC fall but FEV more so, so ratio is reduced. Restrictive: both FEV and FVC fall so ratio remains much the same despite severe compromise of function. Therefore normal FEV1/FVC ratio not always indicative of health!