DSA 2: Respiratory Adaptations Flashcards
Under normal/ideal conditions, the alveolar oxygen and the arterial oxygen should be at ______.
Equilibrium
-consider <12 mm Hg normal
If alveolar oxygen and the arterial oxygen are not in equilibrium, what does that mean?
Diffusion Impairment
- COPD
- Pneumonia
- Interstitial Fibrosis
During hypoventilation, what happens to the alveolar/arterial gradient?
Nothing. Rate of breathing does not affect A-a gradient, which only changes if there the gas exchange process is impaired in some way
What is a physiological shunt?
Blood travelled to the lungs, it didn’t get any oxygen (physiological restriction as in low V/Q ratio)
What is an anatomical shunt?
Blood physically doesn’t enter the lungs (anatomical restriction_)
What is hypoxic vasoconstriction, when does it happen?
Happens when V/Q ratio is low (less oxygen vs. more blood)
- body doesn’t wanna waste blood on dysfunctional alveoli so it redirects it to other alveoli (aka decreasing perfusion)
- ABGs will normalize as body compensates
What is bronchoconstriction?
Happens when V./Q ratio is high (more oxygen vs. less blood)
-Bronchi constricts to increase resistance and stop air from going to an area that doesn’t even get enough blood
What is hypoxia?
Inadequate oxygen available for use by the tissues
What is hypoxemia?
Low oxygen content in the blood
What is hypoxic hypoxia?
Examples of conditions?
hypoxia due to reduced alveolar PO2 leading to reduced PaO2. Not enough O2 to to equilibriate with air
-high altitude, emphysema, fibrosis
What is anemic hypoxia?
Examples of conditions?
hypoxia due to problem with perfusion (not enough RBCs or the RBCs can’t carry the O2)
CO poisoning, which blocks O2 from binding Heme in Hgb
What is circulatory hypoxia?
Example of conditions?
hypoxia due to a problem with the circulation - RBCs not efficiently circulating
Sickle cell anemia - deformed RBCs don’t circulate well and don’t go where they need to go
What is histotoxic hypoxia?
Example of conditions?
hypoxia due to problem with the tissues - unable to use the O2 they get from RBCs
Cyanide poisoning - O2 is used by the poison system preventing cell from using it
If someone is suffering with a disease involving diffusion impairment, would the alveolar ventilation be greater or lesser compared to a healthy individual?
Greater: need more air to maintain oxygen levels
In early lung disease, do we see low or high levels of arterial oxygen?
Normal or low
In early lung disease, do we see low or high levels of arterial carbon dioxide?
Low
How do central chemoreceptors deal with low CO2 (resetting)?
Body wants to increase CO2 (decrease pH). Choroid plexus pumps out H+ to CSF
How does the body compensate for hypercapnia (excess CO2)?
Body wants to decrease CO2 (increase pH). Choroid plexus pumps HCO3- to CSF
With increasing altitude, barometric pressure ____.
With increasing altitude, barometric pressure decreases.
At changing altitudes, what are some immediate reactions the body has to hypoxia and hypocapnia?
Hypoxia (high altitude): Peripheral chemoreceptors increase firing rate > increase ventilation > attempt to increase PaO2 (lower PaCO2)
Hypocapnia (low altitude): Central chemoreceptors increase firing rate > increase PaCO2 > (lower PaO2)
What are ways that body adjusts to high altitude?
1) peripheral chemoreceptors increase ventilation leading to increased PaO2 and lower PaCO2»_space;» basic CSF since we lost CO2»_space;> choroid plexus releases H+ to neutralize it
2) Release of erythropoietin: stimulation of RBC production to increase oxygen carrying capacity
3) Increase size and number of mitochondria to keep up with lack of air coming in
Why does altitude sickness occur?
Symptoms?
Cerebral circulation in response to hypoxia
Low pressure > Cerebral blood vessels will dilate to bring more blood into the area > increase in perfusion pressure = increases filtration leading to mild cerebral edema
-Can cause headache, irritability, insomnia, etc
Why can pulmonary edemas be seen with altitude sickness?
Result of an increase in pulmonary vascular permeability
For every 10 meters below the water surface (sea water) you go, the barometric pressure increases by how much?
1 atm
How do you calculate total barometric pressure?
Total barometric pressure = (Pressure due to water) + (Pressure due to air)
*always remember 1 atm pressure from air
Why is too much oxygen content dangerous?
In excess, oxygen can be toxic due to formation of superoxide anion (O2-) and peroxide (H2O2).
-highly reactive species and are toxic to cells
How can high oxygen content be used to treat someone?
Carbon monoxide poisoning and injuries resulting in or related to decreased perfusion
-can increase oxygen levels in patient
What happens if there is too much nitrogen our system?
Nitrogen narcosis: similar effects of alcohol
Decompression sickness: in a quick ascent (rapid pressure decrease), nitrogen does not have time to reach lungs and instead dissolves in body, which can be quite painful
