Exam 4 Flashcards
The respiratory system plays an important role in maintaining carbon dioxide levels in the blood on a ________ to _______ basis.
Breath to breath basis.
Which buffer system will respond in fractions of a second?
Chemical buffer system.
Which buffer system will respond in few minutes?
Respiratory system.
Which buffer system will respond in 1 or more days?
Renal system.
The carbon dioxide-bicarbonate buffer system involves both the lungs and the kidneys. The lungs regulate the _________ while the kidneys regulate ____________.
- Partial pressure of carbon dioxide.
- Bicarbonate production.
____________ results in carbon dioxide removal from the lungs that exceeds its production by the tissues.
Hyperventilation.
An increase in hemoglobin results in ____________ in the buffering capacity of the blood.
an increase.
On a pH-bicarbonate (Davenport) diagram, movement to a new isobar occurs as the result of a _______________ disturbance.
Respiratory.
On a pH-bicarbonate diagram, movement up or down one isobar occurs as a result of a ______________ disturbance.
Metabolic.
Which of the following can lead to respiratory alkalosis? (select all correct answers):
- Hyperventilation
- Increased pH
- Decreased partial pressure of carbon
dioxide - Hypoventilation
- Hyperventilation.
- Increased pH.
- Decreased partial pressure of carbon dioxide.
Caused by increased ventilation - leading to decreased PaCO2 - leading to decreased PACO2
What factors can lead to metabolic acidosis?
- Decreased pH.
- Ingestion of fixed acids.
- Bad metabolism.
- Severe anemia.
- Loss of bicarbonate.
- Excretion of acid (H+).
What factors can lead to respiratory acidosis?
- Decreased pH.
- Increased CO2.
- Hypoventilation - increased PaCO2 and PACO2.
What factors can lead to metabolic alkalosis?
- Loss of a fixed acid.
- Ingestion of a base.
Respiratory acidosis disturbances are due to:
Changes in ventilation.
Metabolic acid base disturbances are due to:
- Altered metabolism.
- Ingestion of acid/base.
- Renal function.
A patient has a PaCO2 of 60 mmHg that results in an initial pH of approximately 7.2. In response, the kidneys retain bicarbonate and the patient’s final pH is increased to 7.3. This condition would be described as:
A partially compensated respiratory acidosis.
If the initial disturbance is due to a change in PaCO2, the condition will be due to respiratory or metabolic issues?
Respiratory.
Physiological pH:
7.4
Range: 7.35-7.45
Climbing Mt. Everest results in a significant drop in the partial pressure of oxygen in the air. Which of the following adaptations will help to compensate for the resulting drop in the alveolar partial pressure of oxygen? (select all correct answers)
- a decrease in the alveolar
partial
pressure of carbon dioxide - an increase in hemoglobin
saturation - an increase in hemoglobin
concentration - an increase in ventilation
- A decrease in the alveolar partial pressure of carbon dioxide.
- An increase in hemoglobin concentration.
- An increase in ventilation.
An increase in hemoglobin concentration increases the amount of bicarbonate that is available to enter the plasma. This is only possible because
The increased concentration of hemoglobin is able to bind more H+ ions, allowing bicarbonate to move out of the RBC.
Ventilation must be matched to metabolism in order to:
- Minimize the work of breathing.
- Optimize gas exchange.
- Maintain acid-base homeostasis.
Inspiration occurs spontaneously in response to input from respiratory center in the:
Medulla.
True or False: In the same way that the heart can contract without input from the medullary cardiovascular centers, the diaphragm can contract without input from the respiratory center.
FALSE.
Which of the following statements is correct?
- Hyperventilation rapidly raises the PaCO2 to the critical level necessary to force ventilation to occur.
- An individual can over-ride the medullary respiratory inputs to breathe only until the PaCO2 levels reach a critical level and then ventilation will occur.
- Hypoventilation results in an increase in PaO2 levels that result in a slowing of ventilation.
- It is possible to indefinitely over-ride medullary respiratory inputs to breathe.
- An individual can over-ride the medullary respiratory inputs to breathe only until the PaCO2 levels reach a critical level - then ventilation will be forced to occur.
The _____________ is responsible for generating the respiratory rhythm.
Pre-botzinger complex.
The ____________ is responsible for regulating inspiration.
Dorsal respiratory group of the medullary respiratory center.
The _____________ is responsible for regulating expiration.
The ventral respiratory group of the medullary respiratory center.
Output from the medullary respiratory control center can be modified by inputs from:
- Joint proprioceptors
- Stretch receptors.
- Pons respiratory control centers.
- Chemoreceptors.
- Cerebral cortex.
- Temperature receptors.
- Airway irritant receptors.
The diaphragm is ______________ muscle and is innervated primarily by the ____________ branch of the nervous system.
- Skeletal.
- Somatic.
During deep inspirations, the ______________ muscles can contract to help enlarge the thoracic cavity by pulling the ribcage up.
Accessory.
The ____________ nerve is responsible for carrying neural signals from the medullary respiratory centers to the diaphragm.
Phrenic.
The Hering-Breuer inflation reflex:
Inflation of the lungs inhibits further lung inflation - preventing the over expansion of alveoli. .
What is the irritant receptors or RAR?
Receptors in the airway and alveoli that sense mechanical, temperature, and chemical irritants - causing sneezing, coughing, bronchoconstriction (parasympathetic), and decreased ventilation.
Function of the pons respiratory center (PRC):
To provide input to the medullary respiratory center, that regulates rate and depth of respiration. Fine tuning normal respiratory rhythm.
Pons respiratory center is made up of what two centers?
- Apneustic center.
- Pneumotaxic center.
Chemoreceptors detect changes in the composition of _____________ blood.
Arterial.
The _______________ chemoreceptors respond to changes in PaO2.
Peripheral.
The __________ chemoreceptors respond to changes in PaCO2.
Central chemoreceptors.
The peripheral chemoreceptors are located in the:
- Aorta.
- Carotid bifurcation.
The central chemoreceptors are located in the:
Ventral surface of the medulla.
In response to a drop in PaO2, K+ channels in the Type I (glomus) cells ___________, which ultimately leads to a/an _________ in Ca2+ __________.
- Close.
- Increase.
- Influx.
A drop in PaO2, leads to a/an ____________ in afferent signaling to the medullary respiratory center.
Increase.
What are the only chemoreceptors that respond to hypoxemia (very low PaO2)? By what mechanism?
- Peripheral chemoreceptors.
- Hypoxic ventilatory response.
The central chemoreceptors respond to changes in PaCO2 by ultimately detecting changes in ______.
pH
The primary input in the control of ventilation is:
The arterial partial pressure of carbon dioxide - PaCO2
When the peripheral chemoreceptors respond to changes in oxygen, the response is due to changes in ______________.
PaO2
When PaO2 drops below approximately 60 mmHg, alveolar ventilation _________ due to _________________.
increases due to the hypoxic ventilatory response.
A reduction in the PO2 of inspired air can lead to a/an ____________in the arterial partial pressure of carbon dioxide (PaCO2).
decrease.
Stimulation of chemoreceptors is dependant on:
The presence of carbonic anhydrase inside type 1 glomus cells.
True or false: Minute ventilation increased by 3 L/min for every 1 mmHg increase in PaCO2.
True.
Ventilation must be matched to:
Metabolism.
When determining the pressure exerted on the body underwater, which of the following must be taking into account?
- water pressure
- blood pressure
- atmospheric pressure
- alveolar pressure
- Water pressure.
- Atmospheric pressure.
Oxygen toxicity occurs as the result of:
A very high arterial partial pressure of O2 - PaO2.
Oxygen toxicity in aviation is not typically an issue, even when breathing 100% oxygen for long duration due to -
The reduction in barometric pressure.
During a breath-hold dive, the increased pressure on the body results in (select all correct answers)
- increased pulmonary vascular resistance
- compression of the alveolar vessels
- compression of the extra-alveolar vessels
- reduced lung volumes
- Increased pulmonary vascular resistance.
- Compression of the alveolar vessels.
- Compression of extra-alveolar vessels.
- Reduced lung volumes.
Using SCUBA gear allows people to operate under water by providing compressed breathing air. During ascent from depth, it is important to never hold your breath in order to prevent:
Pulmonary barotrauma.
How does hyperventilation allow an individual to hold their breath for longer?
By blowing of more carbon dioxide that is being produced, resulting in a longer time to reach the hypercapnic trigger to increase ventilation.
During shallow water blackout, ______________ is depleted before reaching the _____________ trigger to breath.
- Oxygen.
- Hypercapnic
The _________________ can be voluntarily over-ridden, while the ______________ can not.
- Hypoxic ventilatory response.
- Hypercapnic trigger.
In order to work at extreme depths, which of the following steps must be taken (select all correct answers)
- the percentage of oxygen in the breathing gas must be increased
- the pressure inside the undersea habitat must be maintained at sea level pressure
- the percentage of oxygen in the breathing gas must be decreased
- the percentage of nitrogen in the breathing gas must be decreased
- The percentage of oxygen in the breathing gas must be decreased.
- The percentage of nitrogen in the breathing gas must be decreased.
An anemic individual would experiencing:
Hypemic hypoxia.
True or false: In the Indifferent Stage of Hypoxic Hypoxia, an individual will experience no negative consequences of breathing normal ambient air.
False.
In the Indifferent Stage of Hypoxic Hypoxia, which type of physical performance is most affected with increasing altitude?
Long-duration aerobic activity.
What is hypoxic hypoxia?
A deficiency in alveolar oxygenation.
What factors can lead to hypoxic hypoxia?
- Ascent to altitude - reduced partial pressure of oxygen.
- equiptment issues ;
- Physiological/disease - hypoventilation, reduced lung volume, and V/Q mismatch.
What range in altitude is the physiological zone?
0-10,000 feet.
What range in altitude is the physiological deficient zone?
10,000 to 50,000 feet.
What range in altitude is the space equivalent zone?
50,000 and up feet.
What are the stages of acute hypoxic hypoxia?
- Indifferent stage.
- Compensatory stage.
- Disturbance stage.
- Critical stage.
Critical stage of hypoxic hypoxia is reached when the cell reaches a PO2 of ______ or lower.
40 mmHg.
Effects of the indifferent stage of hypoxic hypoxia:
- Performance is impacted at 4,000 feet of elevation. - Submaximal work performance
- Vision is decreased starting at 4,000 feet.
- Slight increase in heart rate and pulmonary ventilation.
- Acute mountain sickness.
True or false: Level of fitness will impact acute mountain sickness.
FALSE.
In the Compensatory Stage of Hypoxic Hypoxia, hypoxic pulmonary vasoconstriction may occur in response to:
A decrease in PAO2.
The hypoxic ventilatory response can lead to ______________, which can cause _______________.
- Respiratory alkalosis.
- Cerebral stagnant hypoxia.
Loss of consciousness can occur when PaO2 drops below _________ mmHg.
30 mmHg
As the PaO2 drops below approximately 60 mmHg, the _____________ chemoreceptors will __________ their firing rate to the medullary respiratory centers to ____________ alveolar ventilation.
- Peripheral.
- Increase.
- Increase.
True or false: The more physically fit an individual is, the less likely they are to suffer from Acute Mountain Sickness (AMS).
False.
During which stage of Hypoxic Hypoxia are the normal physiological compensatory mechanisms no longer capable of maintaining PAO2 at a level that will ensure normal tissue oxygenation in most individuals?
Disturbance stage.
The compensatory stage of hypoxic hypoxia will cause:
- Cardiovascular responses - Increased heart rate, cardiac output, and blood pressure.
- Respiratory responses - Increased work of breathing due to increased depth of breathing and ventilatory rate.
- Hypoxic ventilatory response (at less than 60 mmHg) - O2 diffusion is limited, CaO2 is decreased, and slight hypoxic pulmonary vasoconstriction.
In hypoxic ventilatory response, which chemoreceptors are being used?
Peripheral chemoreceptors will sense low PaO2 and will trigger increase in ventilation.
Hypoxic ventilatory response will cause negative effects of:
- Respiratory alkalosis - due to increased ventilation causing decreased PACO2, which decreases PaCO2.
- Cerebral vasoconstriction - due to decreased PaCO2.
In the disturbance stage of hypoxic hypoxia what will occur?
- Loss of physiological compensatory mechanisms that provide adequate O2 to tissues.
- Diminished chances of self-recovery.
- O2 saturation of 70-80 percent.
Symptoms that will occur at the disturbance stage of hypoxic hypoxia:
Headache, dizziness, euphoria, fatigue, intellectual impairment, and visual disturbances become severe.
In the critical stage of hypoxic hypoxia what will occur?
- O2 saturation is 60-70%.
- Mental performance is gone, causing severe confusion.
- Physiological compensatory mechanisms can no longer maintain consciousness. (below 30 mmHg)
Which form of hypoxia is associated with decreased O2 carrying capacity of blood?
Hypemic hypoxia
Which form of hypoxia is associated with a decreased perfusion of oxygen?
Stagnant hypoxia.
Which form of hypoxia is associated with an inability of the tissues to accept or utilize O2?
Histotoxic hypoxia.
The physiological effects associated with a decrease in atmospheric pressure include which of the following? (select all correct answers)
- hypoxia
- diet
- decompression sickness
- gas expansion inside the body
- Hypoxia.
- Decompression sickness.
- Gas expansion inside the body.
Ebullism is the term used to describe the vaporization of body water above Armstrong’s Line around 63,000 feet. This event occurs when atmospheric pressure is _________ than the vapor pressure of water at body temperature.
Less.
Ebullism:
A formation of gas bubbles in bodily fluids due to reduced environmental pressure.
The current full pressure suit worn by U-2 pilots is a compromise between all of the following except:
- Mobility
- Cost
- Protection
- Comfort
- Cost.
An individual with a patent foramen ovale (a hole in the atrial septum) is at an increased risk of (select all correct answers)
- hypoxemia
- experiencing an arterial gas embolism (i.e. air in the arterial
- nitrogen narcosis
- oxygen toxicity
- Hypoxemia.
- Experiencing an arterial gas embolism.
For aircrew flying long duration missions in small, single-seat aircraft, it’s important to monitor diet before flights in order to minimize gas production and the movement of waste through the digestive tracts. Which of to following types of foods are recommended for a pilot consume in the 12 - 24 hours prior to flight?
High protein, low fiber - to avoid the need to poop.
The risk of decompression sickness can be reduced (mitigated) for aircrew flying high altitude missions by (select all correct answers)
- breathing 100% oxygen prior to, and during, flight.
- breathing normal air throughout the flight.
- by maintaining a lower cabin altitude by pressurizing the aircraft.
- by performing sub-maximal exercise while pre-breathing (i.e. performing exercised enhanced pre-breathing).
- Breathing 100% oxygen prior to, and during, flight.
- By maintaining a lower cabin altitude by pressurizing the aircraft.
- By performing sub-maximal exercise while pre-breathing.
As we go up in altitude, the amount of time that we have to recognize a problem and self correct (i.e., our Time of Useful Consciousness) rapidly decreases in a non-linearly manner due to:
The relationship between PaO2 and oxygen transport on hemoglobin.
At which physiological division will there typically be no additional counter-measures are needed to maintain normal function in healthy individuals.
Physiological zone.
In which physiological division are Counter-measures necessary to maintain safety and normal function is essentially the same as needed for protecting astronauts
Space equivalent zone.
At which physiological division is Supplemental oxygen necessary to prevent hypoxia.
Physiologically deficient zone.
which physiological division Starts when PaO2 reaches approximately 60 mmHg.
Physiologically deficient zone.
At which physiological division does the Barometric pressure drops to a level that results in the vaporization of body water.
space equivalent zone.
At which physiological division will Most civil aviation (i.e., not commercial aviation) occur?
Physiological zone.
What respiratory compensation could resolve metabolic alkalosis?
Alveolar hypoventilation - causing high PaCO2 - decreasing pH.
Hypercapnia:
High PaCO2.
What metabolic compensation could resolve respiratory alkalosis?
Renal excretion of bicarbonate.
Hypoventilation:
When the lungs do not remove CO2 at the rate it is being produced at – leading to CO2 accumulation in the blood, and a lower pH.
Hyperventilation:
When CO2 is removed faster than it is produced, causing a increase in the pH of the blood.
How does an increased hemoglobin concentration effect blood pH?
Higher concentrations of hemoglobin, cause a pH closer to normal (7.4).
A low concentration of hemoglobin will result in:
- Anemia.
- Less plasma buffering capacity, leading to acidosis.
Peripheral chemoreceptors respond to:
Increased PaO2
Increased PaCO2.
Increased H+
Decreased PaO2.
Lowered pH.
Stimulation of chemoreceptors dependent on the presence of carbonic anhydrase inside Type I (glomus) cells happens when
PCO2 in increased, and pH is decreased.
PCO2 is inversely proportional to:
pH
