Physiology: ventilation & alveolar surface tension

Question 1

what is alveolar surface tension

Answer 1

attraction of water molecules at liquid air interface

Question 2

what does alveolar surface tension allow the alveoli to do

Answer 2

produce a force which resists the stretching of the lungs

Question 3

what would happen if alveolar lining was filled with water alone

Answer 3

surface tension would be too strong and alveoli would collapse

Question 4

what does LaPlaces law mean in terms of alveolar collapse

Answer 4

alveoli with smaller radius have a higher tendency to collapse

Question 5

what is pulmonary surfactant and what type of cell secretes it

Answer 5

mix of lipids and proteins
secreted by type II alveoli
(a.k.a. type II pneumocytes)

Question 6

what is the function of pulmonary surfactant

Answer 6

lowers alveolar surface tension by interspersing between the water molecules lining the alveoli

Question 7

what effect does pulmonary surfactant have on large compared to small alveoli

Answer 7

lowers surface tension more of smaller alveoli

Question 8

explain what alveolar interdependance is

Answer 8

if an alveolus starts to collapse the surrounding alveoli are stretched and then recoil, exerting expanding forces in the alveolus to open it

Question 9

what forces work to keep the alveoli open (3)

Answer 9

transmural pressure gradient, pulmonary surfactant and alveolar interdependance

Question 10

what forces work to collapse the alveoli (2)

Answer 10

elasticity of stretched lungs connective tissue and alveolar surface tension