Exam 2 Flashcards
(299 cards)
What is surfactant?
Active Surface Agent produced by the alveoli.
What does surfactant do?
Reduces surface tension in the alveoli allowing them to stay open
Definition of Perfusion
movement of oxygen to and into the cells
Definition of Diffusion
movement of oxygen across alveolar walls into pulmonary capillaries
Where is pulmonary interstitium located?
Between alveoli and capillary
What does the pulmonary capillaries of alveolar(capillary membrane) do?
form a network around each alveolus so dense that an almost continuous sheet of blood covers the alveoli.
lungs are covered by what?
double layered membrane called pleura
visceral pleura is attached to
lungs
parietal pleura is attached to
chest wall cavity
How large is each capillary?
Interior diameter of each capillary is just large enough to allow red blood cells to squeeze by in single file so that their cell membranes touch the capillary walls
CO2 and O2 do not pass through plasma when
diffusing in and out of the alveoli
Each RBC stays in the pulmonary capillary bed for about how long?
1 second
Each RBC exchanges gases with how many alveoli per second.
2-3 alveoli
What does surfactant do?
lowers surface tension of alveolar walls, increases lung compliance(elasticity), and eases the work of breathing
How often must surfactant be replenished?
continuously
What stimulates surfactant replacement?
normal ventilation
Hypoventilation leads to what?
decreased surfactant/alveolar collapse/atelectasis
What does a normal unit look like: alveoli/capillary
Normal ventilation, normal perfusion
What does a dead space unit look like?
Normal ventilation, no perfusion
What does Shunt unit look like?
No ventilation, normal perfusion
What does a silent unit look like
No ventilation, no perfusion
pulmonary embolism is an example of what kind of space
Dead space unit
How many oxygen molecules can one RBC carry?
1200
If any of the 7 steps of oxygenation get interrupted, what happens?
tissue becomes hypoxic (low oxygen levels)