Lecture 18- Gas exchange in the lungs

Question 1

What is vital capacity?

Answer 1

Tidal volume + inspiratory reserve volume + expiratory reserve volume.

Basically everything you can possibly breath in and out

Question 2

What’s inspiratory capacity?

Answer 2

Tidal volume + inspiratory reserve volume

Basically the total of what you can breath in

Question 3

What are the expected volumes for these in males and females?

1. Tidal volume
2. Expiratory reserve volume
3. Inspiratory rserve volume
4. Residual volume

Answer 3

Males Females

1. 500ml 500ml
2. 1000ml (1L) 700ml
3. 3300ml (3.3L) 1900ml(1.9L)
4. 1200ml (1.2L) 1100ml (1.1L)

Question 4

What’s the total surface area of the alveoli?

Answer 4

70-140m^2. (tennis court)

Question 5

IN the brachial tree there are 23 bifurcations. From when does gas exchange occur?

Answer 5

~ bifurcation 17 onwards

Question 6

What are the layers of the alveolar wall?

Answer 6

• Capillary endothelium
• Basement membrane
• Alveolar epithlium
• Water film

Question 7

What is the respiratory minute volume?

What is the expected volume for this?

Answer 7

1. The amount of air moved per minute.
   Tidal volume x Breathing frequency
2. 500ml x 12/min = 6 litres/min

Question 8

What is alveolar ventilation?

What is th eexpected value?

Answer 8

The amount of air reaching the alveoli each minute. Similar to respiratory minute volume but taking into account anatomical dead space.

Respiratory volume x (Tidal volume - dead space)

12 x (500-150) = 4.2 L/min

Question 9

What is forced vital capacity?

Answer 9

Forcably breathing out vital capacity. From big breath in and breath out as much as you can

Question 10

What is FEV1?

Answer 10

Fprced expiratory volume in 1 sec- volume of air expired forcably in a second, expressed as a % of FVC.