gas exchange Flashcards
how do gasses move in alveoli and capillaries?
by diffusion- down conc gratients
what composes the conducting airways?
trachea, bronchi, nonrespiratory bronchioles
what comprises the respiratory airways?
bronchioles, alveolar ducts and alveoli
where does gas exchange occur?
respiratory airways
how many alveoli do adults have?
300-400 million
what are alveoli composed of?
types 1 & 2 epithelial cells
what is the diameter of alveoli?
250 microm
what is the function and amount of type 1 epithelial cells in alveoli?
97% surface area, primary site of gas exchange
what is the amount and function of type 2 epithelial cells in alveoli?
3% SA, produce pulmonary surfactant
why are alveoli perfect for gas exchange?
large SA, very thin walls, good diffusion characteristics
what does the pulmonary circulation do?
brings deoxygenated blood from heart to lung and oxygenated from lung to heart then rest of body
what does bronchial circulation do?
brings deoxygenated blood to lung parenchyma
what does the lymphatic system do?
defence and removal of lymph fluid
how much blood is in the pulmonary circulation?
10% of total = 500ml
what is the difference in vol. pulmonary blood at rest and at exercise?
at rest = 75ml
exercise = 150-200ml
describe the pressure in the pulmonary system
no high pressure unlike systemic circulation
describe arteries in the pulmonary system
thin walled, highly compliant, larger diameter, low resistance
where does gas exchange occur?
alveolar-capillary network
describe gas exchange in the pulmonary circuit
O2 enters blood
CO2 leaves blood
describe gas exchange in the systemic circuit
O2 leaves blood
CO2 enters
is the pressure gradient for O2 greater or lesser than CO2?
much bigger
is O2 or CO2 more diffusible?
CO2
in which capillary does PO2 go from 100 alveolar air to 40 venous blood ?
pulmonary capillary
in which capillary does PCO2 go from 46 venous blood to 40 alveolar air?
pulmonary capillary
