DSA - Respiratory Adaptations Flashcards
What is the equation for alveolar O2?
inspired O2 - consumed O2
What does the respiration quotient tell us and what is the equation?
Tells the relationship of CO2 and O2 exchange
VCO2 / VO2
What is a normal value of RQ?
0.8
How do you get from the atmospheric pressure to the actual amount of oxygen that you breathe in?
- You subtract 47mm Hg (water vapor pressure at body temperature) from 760 mmHg to get 713 mm Hg
- Since oxygen makes up 21% of the air that we breathe in, you multiply 713 by 0.21 to get 149.7 mmHg
What are the three ways in which the human body can obtain fuel?
- Glucose
- fatty acids
- a mixture
What is the RQ if the body is ONLY using glucose as energy?
1
What is the RQ if the body is using free fatty acids as energy?
0.7
What would the RQ be if the patient is receiving an IV glucose solution?
1.0
What would the RQ be for a patient who is hypoglycemic or a diabetic?
0.7
What is the overall point of the alveolus?
To bring the alveolar oxygen and the arterial oxygen into equilibrium with each other
What is the equation for the alveolar arterial O2 gradient?
PAO2-PaO2
***normal is <12 mmHg
What should you be thinking physiologically if the alveolar arterial gradient is high?
Process of gas exchange was impaired by some disease process
The _______ _________ ______ is the ratio between the amount of air getting into the alveoli and the amount of blood being sent to the lungs
ventilation perfusion (V/Q) ratio
______ is bringing the oxygen into the lungs and removing CO2 from the alveoli
Ventilation
______ is removing the O2 from the alveoli and adding CO2
perfusion
Under normal conditions, ____ liters of ventilation each minute enter the respiratory tract while ____ liters of blood go through the pulmonary capillaries.
4
5
What is the normal value for PAO2?
100 mmHg
What is the normal value for PACO2?
40 mmHg
What is the normal value for PaO2?
95-100 mmHg
What is the normal value for PaCO2
40 mmHg
A decreased in the V/Q ratio is produced by either _____ ventilation or ______ blood flow
Decreasing
Increasing
What happens physiologically if there is a decrease in ventilation?
There is not enough O2 being brought in to meet the metabolic need and not enough CO2 is leaving, so there is an increased amount of CO2 in the body (acidotic)
What happens physiologically if there is an increase in perfusion?
More blood cells are coming to deliver O2 to the cells and then taking more CO2 to the alveoli than will be expired
Increase in CO2…acidotic
What are the three things that you should consider with a decrease in the V/Q ratio?
- Ventilation is not keeping pace with perfusion.
- The alveolar oxygen levels will decrease, which will lead to a decrease in arterial oxygen levels (PaO2)
- The alveolar CO2 levels will increase (we’re not getting rid of it as fast), also leading to an increase in arterial CO2.
What are 2 ways that the V/Q ratio can be increased
Increase ventilation
Decrease perfusion
What is happening in an increased V/Q ratio?
ventilation is in excess of the metabolic needs being met by perfusion so we blow off more CO2 and the PAO2 increases
____ _______ is when one of the two variables (ventilation or perfusion) changes and it is matched with a change in the other variable
V/Q mismatch
***also the term for when there is a variety of V/Q ratios throughout the lung
When you stand up the V/Q ratio (INCREASES/DECREASES) because there is more blood going to the base of the lung while less air gets there
LOWERS
Which portion of the lung is described by the following characteristics?
- less blood
- high ventilation
- high V/Q ratio
- High PAO2 and PaO2
- Decreased CO2
Apex of the lung
Which portion of the lung is being described based on the following characteristics?
- Low V/Q ratio
- Low PAO2 and PaO2
- Increased CO2
Base of the lung
An increase in V/Q to infinity is produced when perfusion goes to _______
zero
In a patient, regions of zero blood flow will result from a _______ _______ that blocks the blood flow.
pulmonary embolism
What will be seen in the blood in the case of a pulmonary embolism?
The blood will be very oxygenated and low CO2
***levels will come close to atmospheric
How do we decrease the V/Q ratio to zero?
stop ventilation to a part of the lung
-blood is sent to alveoli that do not have fresh air coming to them so the blood that results looks similar to the venous blood
effort was wasted in pumping the blood to the lungs
A _______ _______ is when blood travels to the lungs but does not get any oxygen
physiological shunt
An _______ _____ is when blood doesn’t enter the lungs but air is still getting there
anatomical shunt
What is the end result of the shunts?
arterial blood has low oxygen and high CO2
What are two examples of steps that the body can take in order to normalize the V/Q ratio?
- Hypoxic vasoconstriction
2. Bronchoconstriction
In cases where the V/Q ratio is low (lots of blood or too little ventilation),_________ __________ can occur and cause the blood coming into the area to be directed to other parts of the lung.
hypoxic vasoconstriction
What benefit does bronchoconstriction give regarding normalizing the V/Q ratio
bronchi constrict to slightly increase resistance and decrease the amount of ventilation
limits the amount of alveolar dead space that occurs- minimizes “wasted” work that occurs with alveolar dead space
_______ refers to inadequate oxygen available for the use by the tissues
hypoxia
_______ refers to the total absence of oxygen being delivered to the tissue
Anoxia
_______ is the proper term for low oxygen content in the blood
hypoxemia
What are the four types of hypoxia?
- Hypoxic apoxia
- Anemic hypoxia
- Circulatory hypoxia
- Histotoxic hypoxia
In this form of hypoxia, the PaO2 is below normal because either the alveolar PO2 is reduced or decreased equilibrium with blood and alveoli
hypoxic hypoxia
Emphysema and fibrosis are likely involved with which type of hypoxia?
Hypoxic hypoxia: blood is unable to equilibrate fully with the alveolar air
In this form of hypoxia, the lungs are in perfect working condition, but the oxygen carrying capacity of the blood has been reduced.
Anemic hypoxia
What are two reasons that are typically seen with anemic hypoxia?
Carbon monoxide
anemia
In this form of hypoxia the lungs are working just fine and the blood can carry sufficient oxygen. However, the tissue is not receiving sufficient oxygen because the heart cannot pump the blood to the tissue
Circulatory hypoxia
______ ______ _______ can lead to circulatory hypoxia as the cells sickle in the blood vessels and block them.
Sickle cell anemia
In this form of hypoxia, there is no problem getting the oxygen to the tissue - the lungs, blood and circulatory system are all working just fine. However, the tissue is unable to use the oxygen
Histotoxic hypoxia
_______ leads to histotoxic hypoxia by poisoning the systems that utilize oxygen to create energy and preventing them from using the oxygen.
cyanide
Although the central chemoreceptors are responsible for detecting changes in the arterial carbon dioxide levels, they do so by measuring changes in the _______ ______ concentration of the cerebrospinal fluid (CSF)
hydrogen ion
This means that early in lung disease, we may see an low or normal PaO2 with a _____ PaCO2
low
In a patient with a recent diagnosis of a chronic respiratory disease, they will likely develop (hypoxia/hypercapnia) before (hypoxia/hypercapnia)
Hypoxia before hypercapnia
Describe why people with early chronic diseases struggle to breathe/ keep blood gasses up
The ventilation needs to occur at an increased level to maintain the oxygen levels but the hypocapnia is going to decrease his drive to breathe which causes his oxygen levels to fall more
In a chronic disease state, what does the brain do to compensate?
Takes the new lowered PaCO2 values as normal VIA the composition of the CSF
How does CSF differ from extracellular fluid?
There is MUCH less protein and almost no cholesterol
more bicarbonate in CSF than in the plasma
How is the composition of the CSF able to be changed?
There are carbonic anhydrides that are located in the choroid plexus that can selectively pump hydrogen or bicarbonate out
In the event of _____ ______, the patient is retaining CO2 which leads to acidosis and acidifying of CSF
Chronic hypercapnia
CSF acidification stimulates _______
Breathing
With increasing altitude, the barometric pressure ______ but the FIO2 stays the same at 21%
decreases
What happens to the blood the farther that you go up in altitude?
The blood starts to become more similar to venous blood
What is a normal hemoglobins and oxygen content in the blood
14.1 mL O2/ dl blood
What are the acute responses to altitude
- immediate response to hypoxia
- An increase in alveolar ventilation
- Decreased PaCO2 causes a decreased firing rate of central chemoreceptors
the immediate response to hypoxia is mediated through the _______ _________.
peripheral chemoreceptors
Peripheral chemoreceptors begin to increase their firing rate at about a PaO2 of ____ mm Hg and will increase ventilation in response to the hypoxia
70
An (INCREASE/DECREASE) in alveolar ventilation will (INCREASE/DECREASE) the PaO2.
Increase
increase
The (INCREASE/DECREASE) PaCO2 causes a INCREASE/DECREASE) in the firing of the central and central chemoreceptors.
Decreased
Decrease
Chronic hypoxia/hypocapnia will produce the long-term changes known as ________
acclimatization
Describe the first step of acclimation.
The CSF is more basic than normal so the choroid plexus will pump out more H+ or less bicarb
Increases the pH to normal
Peripheral chemoreceptors can drive ventilation in response to hypoxia
central chemoreceptors maintain the PaCO2 at a normal level
Describe stage 2 of acclimation
Erythropoietin is released from the kidney and stimulates RBC production
increases hematocrit and increases Hb blood content and oxygen carrying capacity
Describe step 3 of acclimization
Cells of the body increase the number and size of mitochondria— anaerobic glycolysis
allows cells to efficiently use O2 that is delivered
The cause of ______ ______ is the changes of cerebral circulation that occurs in response to hypoxia
Altitude sickness
What is the overall effect of altitude sickness that makes to so dangerous
Cerebral edema secondary to the dilation of the blood vessels following hypoxia
People who rapidly descend elevations are more at risk for _______ _______
pulmonary edema
_________ _______ is the result of hypoxic vasoconstriction and an increased work load on the RV
Pulmonary HTN
For every ____ m below the surface of water you go, barometric pressure changes by ____ atm
10
1
What is the equation for total barometric pressure?
TBP= pressure due to water + 1 atm
What are some of the effects of oxygen toxicity?
Oxygen toxicity results in irritation of the tracheobronchial tree, nasal congestion, sore throat, coughing, muscle twitching, tinnitus (ringing in the ears), dizziness, convulsions, and death.
Why can oxygen at high amounts be toxic?
formation of the superoxide anion and peroxide
highly reactive and toxic to cells
When is hyperbaric treatment useful?
Carbon monoxide poisoning and injuries that cause decreased perfusion
At higher concentrations, nitrogen exerts an effect very similar to alcohol on the neurons of the CNS, known as…
nitrogen narcosis
Briefly describe “the bends” sickness
AS you ascend, the nitrogen leaves the dissolved state and becomes a gas, infiltrating the blood with little bubbles that are painful
During ascent, the ____ must remain open so that expanding air can leave the lungs
glottis
What happens if the glottis does not remain open during an ascent?
Then the air cannot leave the lungs, to enters the blood and causes an air embolus which can kill you
