DSA 2: Respiratory Adaptations

Question 1

Under normal/ideal conditions, the alveolar oxygen and the arterial oxygen should be at ______.

Answer 1

Equilibrium

-consider <12 mm Hg normal

Question 2

If alveolar oxygen and the arterial oxygen are not in equilibrium, what does that mean?

Answer 2

Diffusion Impairment

• COPD
• Pneumonia
• Interstitial Fibrosis

Question 3

During hypoventilation, what happens to the alveolar/arterial gradient?

Answer 3

Nothing. Rate of breathing does not affect A-a gradient, which only changes if there the gas exchange process is impaired in some way

Question 4

What is a physiological shunt?

Answer 4

Blood travelled to the lungs, it didn’t get any oxygen (physiological restriction as in low V/Q ratio)

Question 5

What is an anatomical shunt?

Answer 5

Blood physically doesn’t enter the lungs (anatomical restriction_)

Question 6

What is hypoxic vasoconstriction, when does it happen?

Answer 6

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

Question 7

What is bronchoconstriction?

Answer 7

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

Question 8

What is hypoxia?

Answer 8

Inadequate oxygen available for use by the tissues

Question 9

What is hypoxemia?

Answer 9

Low oxygen content in the blood

Question 10

What is hypoxic hypoxia?

Examples of conditions?

Answer 10

hypoxia due to reduced alveolar PO2 leading to reduced PaO2. Not enough O2 to to equilibriate with air

-high altitude, emphysema, fibrosis

Question 11

What is anemic hypoxia?

Examples of conditions?

Answer 11

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

Question 12

What is circulatory hypoxia?

Example of conditions?

Answer 12

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

Question 13

What is histotoxic hypoxia?

Example of conditions?

Answer 13

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

Question 14

If someone is suffering with a disease involving diffusion impairment, would the alveolar ventilation be greater or lesser compared to a healthy individual?

Answer 14

Greater: need more air to maintain oxygen levels

Question 15

In early lung disease, do we see low or high levels of arterial oxygen?

Answer 15

Normal or low

Question 16

In early lung disease, do we see low or high levels of arterial carbon dioxide?

Answer 16

Low

Question 17

How do central chemoreceptors deal with low CO2 (resetting)?

Answer 17

Body wants to increase CO2 (decrease pH). Choroid plexus pumps out H+ to CSF

Question 18

How does the body compensate for hypercapnia (excess CO2)?

Answer 18

Body wants to decrease CO2 (increase pH). Choroid plexus pumps HCO3- to CSF

Question 19

With increasing altitude, barometric pressure ____.

Answer 19

With increasing altitude, barometric pressure decreases.

Question 20

At changing altitudes, what are some immediate reactions the body has to hypoxia and hypocapnia?

Answer 20

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)

Question 21

What are ways that body adjusts to high altitude?

Answer 21

1) peripheral chemoreceptors increase ventilation leading to increased PaO2 and lower PaCO2&raquo_space;» basic CSF since we lost CO2&raquo_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

Question 22

Why does altitude sickness occur?

Symptoms?

Answer 22

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

Question 23

Why can pulmonary edemas be seen with altitude sickness?

Answer 23

Result of an increase in pulmonary vascular permeability

Question 24

For every 10 meters below the water surface (sea water) you go, the barometric pressure increases by how much?

Answer 24

1 atm

Question 25

How do you calculate total barometric pressure?

Answer 25

Total barometric pressure = (Pressure due to water) + (Pressure due to air)
*always remember 1 atm pressure from air

Question 26

Why is too much oxygen content dangerous?

Answer 26

In excess, oxygen can be toxic due to formation of superoxide anion (O2-) and peroxide (H2O2).
-highly reactive species and are toxic to cells

Question 27

How can high oxygen content be used to treat someone?

Answer 27

Carbon monoxide poisoning and injuries resulting in or related to decreased perfusion
-can increase oxygen levels in patient

Question 28

What happens if there is too much nitrogen our system?

Answer 28

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