51R. Gas Exchange

Question 1

what is anatomical dead space

Answer 1

some inspired air remains in the airways where it is not available for gas exchange

Question 2

what is the equation and for pulmonary ventilation

Answer 2

PV= tidal volume x respiratory rate

Question 3

what is pulmonary ventilation

Answer 3

total volume of air that is inhaled and exhaled from the lungs per minute

Question 4

which is always less? Alveolar Ventilation or Pulmonary Ventilation and why

Answer 4

alveolar ventilation as some of the inspired air stays in the airway/dead space so isnt exchanged

Question 4

what is alveolar ventilation

Answer 4

the volume of air that actually reaches the alveoli and is available for gas exchange per minute

Question 5

what is alveolar ventilation equation

Answer 5

AV= (tidal volume - dead space volume) x respiratory rate

Question 6

what is boyles law

Answer 6

‘Pressure (P) of a gas is inversely proportional to its volume (V)’ (if temperature & number of gas molecules remains constant in a closed system)

Question 7

Partial pressure of an individual gas in a gas mixture is explained by Dalton’s Law. What does it state?

Answer 7

In a mixture of gases, the total pressure = the sum of the partial pressures of the individual gases

Question 8

what is atmospheric pressure at sea level

Answer 8

101 kilopascals

Question 9

in the atmosphere, what are the partial pressures of the gases in percentage

Answer 9

O2 = 20.9%
N2 = 78%
CO2 = 0.03%

Question 10

gases dissolve and diffuse according to what

Answer 10

their partial pressure and the partial pressure gradient

Question 11

When Inspired Gases Come in Contact with Body Fluids what happens

Answer 11

they dissolve in liquid

Question 12

Water molecules from the body fluids can do what

Answer 12

evaporate and enter the air

Question 13

Water molecules from the body fluids can evaporate and enter the air which creates pressure. What is this pressure called

Answer 13

vapour pressure

Question 14

At body temperature inhaled air becomes saturated with water vapour in the upper respiratory tract what is this pressure called

Answer 14

Saturated vapour pressure

Question 15

what is the solubility coefficient

Answer 15

is a constant for the individual gas and the solvent

Question 16

what is partial pressure

Answer 16

pressure exerted by the dissolved gas in liquid

Question 17

what is the concentration of dissolved gas

Answer 17

Number of mmol of gas, dissolved in a litre of liquid

Question 18

What is the total content of gas

Answer 18

= dissolved gas + gas bound to or reacted with a component
( e.g. O2 dissolved plasma + O2 bound to Hb)

Question 19

how many oxygens can haemoglobin carry

Answer 19

4

Question 20

what two ways does your blood carry oxygen

Answer 20

on haemoglobin (proteins) and dissolved in plasma

Question 21

When oxygen (O₂) moves from the alveolar air into the red blood cells (RBCs) in the capillaries, it must cross several layers

Answer 21

5 Cell Membranes:
- Alveolar Epithelial Cell Membrane (entering the epithelial cell).
- Alveolar Epithelial Cell Membrane (exiting the epithelial cell).
- Capillary Endothelial Cell Membrane (entering the endothelial cell).
- Capillary Endothelial Cell Membrane (exiting the endothelial cell).
- Red Blood Cell Membrane (entering the RBC).

3 Layers of Cytoplasm:
- Alveolar Epithelial Cell Cytoplasm.
- Capillary Endothelial Cell Cytoplasm.
- Red Blood Cell Cytoplasm.

2 Layers of Tissue Fluid and Plasma:
Interstitial Fluid (between the alveolus and capillary).
Plasma (the liquid part of the blood).

Question 22

how thick is the barrier

Answer 22

<0.4 micrometers

Question 23

what is the surface area of the alveolar capillary membrane

Answer 23

100 m2

Question 24

what 3 factors affect rate of diffusion - in disease

Answer 24

thickness of membrane
surface area of membrane
diffusion coefficient of the gas

Question 25

explain the 3 factors affecting rate of diffusion - in disease

Answer 25

Thickness of the Membrane
Oedema: This is like adding extra layers because of fluid buildup.
Lung Fibrosis: This makes the the membrane even thicker because of scarring.

Surface Area of the Membrane
Removing a Lung
Emphysema

Diffusion Coefficient of the Gas
CO₂ (Carbon Dioxide): super fast and can move easily.
O₂ (Oxygen): slower and has a harder time moving.

Question 26

The V/Q ratio (ventilation/perfusion ratio) should be close to ……..for optimal gas exchange.

Answer 26

1

Question 27

Your lungs have about ………. million alveoli, and they can have different amounts of ventilation and perfusion.

Answer 27

300

Question 28

For the best gas exchange, the amount of air (ventilation) and the amount of blood (perfusion) should be ……..

Answer 28

matched

Question 29

When the oxygen level (pO₂) in the alveoli is low, the blood vessels (pulmonary arterioles) constrict (get smaller).
This process is called….?

Answer 29

hypoxic vasconstriction