gas exchange Flashcards
what is a surfactant
substance produced by type II alveolar epithelial cells in the lungs and is primarily made of phospholipids
type I alveolar cells
squamous epithelial cells, cover majority of alveolar surface, important component of air-blood barrier
type II alveolar cells
cuboidal, with characteristics of a secretory cell, highly metabolic
what 3 important activities do type II alveolar cells carry out
surfactant production
surfactant homeostasis
repair of the alveolus following injury
role of surfactant
reduce surface tension created by fluid lining alveoli, interferes with hydrogen bonds between water molecules
infant respiratory distress syndrome
consequence of lack of surfactant
foetus starts producing surfactant between 24-28 weeks
if born before 35 weeks, may not be sufficient surfactant, alveoli collapse
dalton’s law
total pressure is equal to the sum of the partial pressures
henry’s law
solubility of a gas in a liquid is proportional to its partial pressure above the liquid and solubility coefficient of the gas in the liquid
fick’s law
amount of gas diffusing through a barrier is inversely proportional to the thickness of the barrier, and directly proportional to the surface area of the barrier
graham’s law
rate of diffusion is directly proportional to the solubility coefficient of the gas and inversely proportional to the total the square root of its molecular weight
properties that maximise gas exchange
large surface area
dense capillary network
thin alveolar-capillary membrane
production of surfactant
diffusion capacity increases during exercise
larger tidal volumes, inflate alveoli and increase SA, more pulmonary capillary’s perfused, increased pp gradient
reduction in diffusing capacity
thickening of air-blood barrier (pulmonary oedema), reduction in alveolar surface area (emphysema)
parital pressure of oxygen in the alveoli
104mmHg
partial pressure of oxygen in arterial end of capillaries
40mmHg
