resp 6 Flashcards
Hypoxia
the state in which oxygen is not available to maintain homeostaisis
What are the two causes of low alveolar PO2 (hypoxia) assuming perfusion remains constant?
- inspired air has low O2 content.
- alverolar ventilation (hypoventillation). if the atmosphere is O2 suffecient then it must be somwthing wrong with ventilation.
note: if the cause for low O2 is neither of these, then the problem usually lies within gas exchange between the alveoli and blood
what is going to affect the random movement of gas molecules between the alveoli and capillaries?
- concentration gradient
- surface area
- barrier permeability
- diffusion distance
what is the diffusion rate formula
diffusion (directly proportional to) surface area x concentration gradient x barrier permeability
what is Pulmonary Edema?
Increased Diffusion distance
fluid in interstital space increases diffusion distance.
how does gas soluability affect diffusion?
since the gas has to go from gas to liquid, there are things that affect its diffusion into the liquid.
(oxygen isnt good at diffusing into liquid as CO2 is, that is why we have hemoglobin)
- the pressure gradient of the gas
- solubility of gas in liquid
3 temurature-relatively constant
Mass flow
oxygen transport in ciculation and oxygen consumption by tissues
(movement of X per minute)
O2 transport/min = Cardiac Output (CO) x O2 concentration
Mass Balance
any substance in the body must remain constant
arterial O2 transport - QO2 = Venous O2 transport
Where is most of O2 bound and transported by?
98% of O2 in blood is bound to hemoglobin
the other 2% is dissolved in plasma
mass flow formula
O2 transport = CO x O2 concentration
Mass Balance formula
Arterial O2 transport - Venous O2 transport = QO2
Oxygen consumption by systemic tissues formula
CO x (arterialO2 - VenousO2) = QO2
