CGIER 32 - Surface tension and osmosis

Question 1

How does alveoli of diameter influence inflation of alveoli

Answer 1

easier for smaller alveoli collapse and require more energy for the smaller alveoli to inflate. Won’t be too much of a problem as there are bigger alveoli that will compensate for the,

Question 2

why do we yawn

Answer 2

there are some small alveoli that collapse - when there are too many alveoli that collapse then that will induce yawning when more energy and oxygen is needed to inflate them

Question 3

what is internal surface alveoli coated with and what does it contain

Answer 3

liquid film
contain long molecules of lipo-proteins
act as surfactants/Surface Active Agents - reduces size of surface tension
inert tail - insoluble in liquid
polar head -

Question 4

describe surface tension and surfactant concentration during inhalation

Answer 4

low surfactant conc.

Laplace’s law - tension of tissue is high

Question 5

describe surface tension and surfactant concentration during exhalation

Answer 5

surfactant molecules closer together and more concentrated

lower surface tension

Question 6

how does surface tension contribute to expiration

Answer 6

Surface tension contributes ~ half of the force in expiration (other half comes from tissue elasticity). Effect of surfactant means healthy lungs only deflate to ~ ¼ of the max. inspired volume.

Question 7

when is osmotic pressure always present

Answer 7

Osmotic pressures will always occur where there is a difference in solute concentration across a semi-permeable membrane.

Question 8

describe lysis

Answer 8

occurs in hypotonic solution water diffuses into the cell which swells and bursts (lysis) due to the huge internal osmotic pressure

Question 9

describes crenation

Answer 9

, the cellular plasma flows out of the cell, which shrivels up (krenation).

Question 10

consequences of aspirated saltwater

Answer 10

sea water introduced into alveoli will be hypertonic

Osmosis occurs forces plasma out of lungs - lungs fill with fluid - secondary drowning

Question 11

consequences of aspired fresh water

Answer 11

fresh water - hypotonic solution
osmosis will force it from lungs into the blood stream via lungs
dilute blood stream
haematocrit is lower - heart will be put under stress - fewer red blood cells to distribute oxygen

Question 12

what does inhalation of water also impact in the lungs?

Answer 12

dilutes surfactant - higher surface tension harder to inflate- makes respiration difficult afterwards