Volumes and Pressure Lecture 2

Question 1

Describe TLC, FRC, RV, Vt, ERV, IRV

Answer 1

TLC= total lung capacity (biggest breath in)

FRC = end of passive expiration

RV = residual volume (how much you can blow out)

Vt = tidal volume

ERV = expiratory reserve volume

IRV = inspiratory reserve volume

Question 2

Describe units of measuring pressure

Answer 2

1cmH2O= 0.75mmHg= 0.1kPa

All relative to atmospheric pressures

Question 3

Ideal gas law

Answer 3

for a dry gas (when you breathe in, it isnt dry gas anymore)

PV = nRT or P = nRT/V

P = pressure (Pa), V = volume (m³), n= number of moles, R=gas contant (J.K^-1.mol^-1), T = temperature (K)

At constant T and V:

P is proportional to n

Pressure is dependant to number of gas molecules

Question 4

What is daltons law

Answer 4

each gas in a dry mixture exerts a partial pressure proportional to its fractional share of the total volume.

Partial pressure of a gas is dependant on the number of gas molecules.

Partial pressures all dd up to the total gas pressure

Question 5

What is a the partial pressure?

Answer 5

Relative pressure exerted by a component of a gas mixture based on the number of molecules.

Important as we need it for diffusion/convection.

Partial pressure gradeint gives the concentration for diffusion

Question 6

What is the function of the upper airways?

Answer 6

Filtering Warming Humidifying Distribution

Upper airways saturate the air and warm to body temperature

Partial pressure of H2O is dependent on temperature but not altitude and the human body is always at 37C

Question 7

What are the different conditions to measure gas mixture?

Answer 7

STPD- standard temperature (0 degrees), pressure, dry

BTPS- body temperature (37 degrees), pressure, saturated

Question 8

What is Boyle’s law?

Answer 8

At a constant temperature the pressure exerted by a constant number of particle is inversely proportional to the volume of the container

P=k.1/V

Question 9

Where can pressure be measured?

Answer 9

1. Outside chest wall Patm
2. Between pleural membranes Ppl
3. Inside alveoli P(A)
4. Inside the airways Paw

Pressure are relative to atmospheric pressure

Pressure differences/gradients are important