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Question 1

Henderson-Hasselbach Equation

Answer 1

pH = 6.1 (pKa) + log10([HCO3-] / [0.03*PCO2])

Question 2

What does the 6.1 in the Henderson-Hasselbach equation represent?

Answer 2

6.1 is the dissociation constant for the bicarbonate buffer system i.e. pKa

Question 3

0.03 in the Henderson-Hasselbach equation is the…

Answer 3

…blood CO2 solubility co-efficient i.e. the proportion of CO2 that will form H2CO3 in solution

Question 4

0.03*PCO2 in the Henderson-Hasselbach equation is an estimate of the…

Answer 4

…concentration of H2CO3 (0.03 is the blood CO2 solubility co-efficient)

Question 5

Boyle’s Law

Answer 5

P1V1 = P2V2 | The pressure of gas in a container is inversely proportional to the container’s volume

Question 6

Dalton’s Law

Answer 6

Total Pressure = Sum of Partial Pressures of Each Individual Gas in Mixture - the partial pressure of a gas is directly proportional to its concentration

Question 7

Alveolar Gas Equation

Answer 7

PAO2 = PiO2 - (PaCO2 / R) | R is the ratio between the amount of CO2 produced in metabolism and the amount of O2 used - it is also known as the ‘respiratory exchange ratio’

Question 8

Law of Laplace

Answer 8

Pressure (P) = 2T (surface tension) / r (radius of alveolus)

Question 9

Inspiratory Reserve Volume (IRV)

Answer 9

Amount of additional air that can be inhaled after tidal inspiration, with maximum effort

Question 10

Expiratory Reserve Volume (ERV)

Answer 10

Amount of additional air that can be forcibly expired with maximum effort after normal tidal exhalation

Question 11

Residual Volume (RV)

Answer 11

Amount of air remaining in the lungs after maximum expiration; keeps the alveoli inflated between breaths and mixes with fresh air on next inspiration

Question 12

Vital Capacity (VC)

Answer 12

Amount of air that can be exhaled with maximum effort after maximum inspiration (ERV + TV + IRV); used to assess strength of the thoracic muscles as well as pulmonary function

Question 13

Functional Residual Capacity (FRC)

Answer 13

Amount of air remaining in the lungs after a normal tidal expiration (RV + ERV)

Question 14

Inspiration Capacity (IC)

Answer 14

Maximum amount of air that can be inhaled (TV + IRV)

Question 15

Total Lung Capacity (TLC)

Answer 15

Maximum amount of air the lungs can contain (RV + VC)

Question 16

Tidal Volume (TV)

Answer 16

Amount of air inhaled or exhaled in one breath - 500ml/breath on average

Question 17

FEV1

Answer 17

Forced expiratory volume in 1 second - FEV1/FVC worked out, below 80% is abnormal

Question 18

FVC

Answer 18

Forced vital capacity, the total amount of air forcibly expired from the total lung capacity (TLC) - compared against predictive values, if the FVC = <80% then value is abnormal, this is airway restriction e.g. restrictive lung disease

Question 19

FEV1/FVC

Answer 19

This is the proportion of FVC expired in 1 second, if ratio is below 0.7 then there is an airways obstruction e.g. COPD - if value is normal but the FVC is low then there is a restrictive disorder

Question 20

Transpulmonary Pressure (Ptp)

Answer 20

Difference in pressure between the inside and outside of the lung (Palv - Pip)

Question 21

Intrapleural Pressure (Pip)

Answer 21

The pressure in the pleural space, also known as the intrathoracic pressure

Question 22

Alveolar Pressure (Palv)

Answer 22

Air pressure in pulmonary alveoli

Question 23

Airway Resistance

Answer 23

Poiseuille’s law: R = 8ƞl / πr^4 - ƞ=viscosity and l=length

Question 24

PaCO2

Answer 24

PaCO2 = kV̇CO2 / V̇A - the arterial partial pressure of CO2 is inversely related to the alveolar ventilation

Question 25

Henry’s Law

Answer 25

S1/P1 = S2/P2 - the solubility of a gas is proportional to the partial pressure of the gas

Question 26

Tidal Ventilation

Answer 26

Tidal Ventilation = Tidal Volume x Respiratory Rate