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48 Cards in this Set

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  • Back
The main muscle of inspiration is the diaphragm? TRUE/FALSE
List 6 accessory muscles of inspiration.
1. pectoralis major/minor
2. serratus anterior
3. sternocleidomastoid
4. scalene muscles
5. levatores costarum
6. serratus posterior superior.
If one forcefully exhales, what muscles are employed?
1. external/internal intercostals
2. transversus thoracis and innermost intercostals.
3. external/internal oblique
4. transversus abdominus muscles.
O2 is not very soluble in plasma. TRUE/FALSE
TRUE. Most O2, about 97% is transported via hemoglobin.
Hemoglobin maintains near saturation(above 90%) even when alveolar O2 decreases from the normal 104mm Hg to 60mmHg. TRUE/FALSE
TRUE. However, when hemoglobin encounters the low tissue pO2 of the body tissues(about 40mmHg) in interstitial fluid, it readily gives up the O2.(marked exercise)
What is the relationship between hemoglobin and CO2?
Hemoglobin releases more O2 when the PCO2 is elevated or the pH is low, or when the temperature is elevated.
How does altitude affect alveolar O2 capture?
If alveolar pO2 levels fall really low, particularly below 40(at about 20,000 ft) when adequate amounts of O2 do not reach the alveoli, hemoglobin will falter in trapping O2 anf the patient will go downhill.
CO2 combines with water in the RBC to form H2CO3( carbonic anhydrase in the RBC catalyzes this reaction. TRUE/FALSE
The H+ from the H2CO3 combines with the hemoglobin; HCO3 leaves the cell and floats around in the blood until the blood reaches the lungs.
Regarding the previous question, what happens once the blood reaches the lungs?
The hemoglobin releases the H+, which combines with bicarbonate ion to reform CO@, which is then expelled from the lungs.
Some CO2 will combine directly with hemoglobin(about 25% to form carbaminohemoglobin, which releases its co2 in the lungs. Only 5% dissolves in the plasma.
What is the chloride shift?
When CO2 dissolves in the RBC fluid at the capillary level, the HCO3, that leaves the RBC exchanges with chloride, to maintain ionic charge neutrality. This process reverses in the lungs. Therefore the chloride content of venous RBCs is greater than that of arterial RBCs(chloride shift)
The rate limiting step in the cells utilization of O2 is not the pO2, but the level of ADP. The cell needs O2 to form its energy currency, ATP, from ADP duringoxidative phosphorylation. If the level of ATP is low, that is ATP is high, the cell doesnt need as much O2. If ADP is high, and ATP is low the cell needs to use more O2 to form ATP and more O2 reacts during oxidative phosphorylation. TRUE/FALSE
Which nerves innervate the diaphragm?
The phrenic nerve(C3,4 and 5) innervates the diaphragm and receives volontary and involontary respiratory messages from the CNS.
Respiratory centers in the brain stem medulla and pons help control the involontary aspects of respiration.
Hoe does CO2 and H+ influence brain stem feedback?
Increased blood CO2 or H+, levels stimulate the brain stem respiratory centers to increase respiration to blow off CO2.
Increased CO2 and decreased pH also stimulate increased firing of the aortic and carotid bodies, which relay neural messages to the brain stem via cranial nerves 9 and 10 to augment respiration.
decreased blood O2 levels increase firing of the carotid and aortic bodies, which relay the information about the state of blood oxygenation to the brain stem. TRUE/FALSE
In exercise it is believed that the motor cortex sends direct innervation to stimulate the brain stem respiratory centers at the same time that the brain sends impulses to the skeletal muscles to engage in exercise.
What is the Hering-Breuer reflex/
Stretch receptors in the bronchiolar and bronchial tree send inhibitory impulses to the brain stem that limit excessive inspiration( and increase the rate of inspiration).
Deep hyperventilation, however, may help you hold your breath longer, because it expands your lungs and replaces fresh air with some of the tracheal and bronchial low O2 dead space. This puts more reserve air in the lung to use while the breath is held. TRUE/FALSE
Normal outside air consists of about 20% O2, 79% nitrogen, 0.04% CO2 and <1%water(depending on humidity). TRUE/FALSE
The pressure of alveolar air at sea level is about 760mmHG but differs in composition from atmospheric air since it includes water vapor from the body(about6%).
As one climbs above 45,000 ft or so, the atmospheric pressure is so low that even pure O2 cannot provide enough O2 saturation to the blood, since the alveolar pO2 is so low. TRUE/FALSE
What type of conditions may cause respiratory problems?
Stroke/ brain stem edema from injury, drug overdosage, ALS, spinal cord injury or polio.
What is Cheyne-Stokes respiration?
It is a classic pattern of breathing in brain stem injury. In this type of respiration, there is an overcompensation of deep rapid breathing, which leads to decreased CO2 and shutoff of respiration. This leads again to a builup of CO2 and return of the overcompensated breathing pattern.
What is Pneumothorax?
Air abnormally enters the pleural space. This causes lung collapse and does not allow the necessary negative pressure to develop inside the lung during inspiratory diaphragmatic contraction.
What is emphysema?
In this condition, there is alveolar destruction, decreased alveolar surface area, and decreased gas exchange. O2 uptake and CO2 release are poor.
Diminished surface area through collapse or replacement of the alveolar space(atelectasis, pulmonary fibrosis, emphysema, invasive tumor). TRUE/FALSE
One must be cautious in a too rapid lowering of pCO2 by mechanical ventilation. The resulting alkalosis may cause cerebral vasoconstriction and coma.
CO2 diffuses much better than O2 between air and the blood because it is far more soluble than O2. TRUE/FALSE
When O2 supply cannot meet the tissue energy needs during marked exercise, the body switches to anerobic metabolism, rather than the O2 dependent Krebs cycle. TRUE/FALSE
TRUE. However, this is energy inefficient, and the individual is also limited by the accumulation of lactate and H+ in the muscle, with compensatory hyperventilation.
What are the normal gas values in arterial blood.
Normal arterial pH is about 7.35-7.45. Normal serum bicarbonate is about 24-28meq/L.
Normal arterial pO2 is about 95mmHg, and normal arterial pCO2 is about 40mmHg.
What is tidal volume/
It is the amount of air normally inhaled(or exhaled) with each average breath(about 500ml).
What is the "Inspiratory reserve volume"?
It is the extra amount you could have inhaled after breathing in normally.
What is Expiratory reserve volume?
It is the extra amount you could have exhaled after exhaling normally.
Residual volume is the residual left in the lung after the strongest expiration. TRUE/FALSE
If there were no residual volume there would be marked fluctuations in CO2 and O2 content of bloodpassing through the lungs during respirations.
What is Vital capacity/
It is the amount of air exchanged from the maximal intake to the most forceful expiration.
What is compliance?
The compliance of the respiratory system is thr increase in chest volume with each degree of increase of alveolar pressure.
Compliance depends partly on the distensibility of the lungs, which can be impeded by patholgy, such as fibrosis, edema and obstruction. TRUE/FALSE
TRUE. Compliance = change of volume with regard to change in pressure.
What is Elastance?
It is simply the reciprocal of compliance. It refers to the tendency of the respiratory system to spring back to its original shape after expansion.
What is surfactant?
Elastance is partly due to surface tension produced by the fluid coating in the alveoli which tends to resist expansion. The surface tension is normally kept at a reduced level by surfactant, a lipoprotein produced by the alveolar epithelium.
What is Hyaline membrane disease? (Infant respiratory distress syndrome).
In this condition the newborn does not produce enough surfactant and hence the lungs cannot expand well due to the increased elastic resistance. The alveoli instead have a tendency to collapse(atelectasis).
Hypoxia in adults can also cause a loss of surfactant(either by decreasing its production or increasing its destruction), leading to adult respiratory distress syndrome(shock lung syndrome). TRUE/FALSE
What is total lung capacity?
It is the total amount of air in the lung after a forced inspiration.
What is minute respiratory volume?
It is the amount of air exchanged per minute. MRV=tidal volume(about 500ml) X respiratory rate(about 12 breaths/min) = about 6 liters/min.
What is Dead space volume?
It is the extra alveolar area of the pulmonary tree(trachea and bronchial tree) in which no gas exchange with the blood circulation. It is about 150 ml in adults.
What is Alveolar ventilation/
the volume of fresh air entering the alveoli each minute.
Alveolar vent.= respiratory rate X (tidal volume- Dead space volume).
An important distinction between obstruction and restrictive lung disease is that residual lung volume(RV) is increased in obbstructive disease, but decreased in restrictive disease. TRUE/FALSE.
Spirometry cannot measure RV. It can measure however tidal volume, IRV and ERV.
In asthma, bronchitis and emphysema, expiration is more difficult than inspiration, since the positive pressure of expiration collapses the respiratory passages. TRUE/FALSE
O2 therapy may be useful in hypoxia secondary to poor atmospheric oxygenation or poor pulmonary gas exchange. When is O2 therapy not very useful?
It is not useful in anemia or other disorders of blood cells, where there are too few blood cells or impaired RBC function.
O2 also does not help where there is impaired tissue utilization of O2, as in cyanide poisoning.
Might o2 therapy help in CO poisoning?
It might. CO binds more strongly than does O2 to the same site on the hemoglobin molecule, in effect, reducing the number of available RBCs.
Infact, treatment with pure O2 or hyperbaric O2 can displace some CO by competition.
Regarding hypoxemic respiratory failure, is it important to avoid too high an O2 concentration?
Yes. The arterial pO2 should be about 60mmHG, and since too high a pO2 may decrease the patients respiratory drive, and the patients already elevated PCO2 may rise even more, worsening the respiratory acidosis.
What is PEEP?
(positive end-expiratory pressure) is a form of positive pressure respiration that keeps the alveolar pressure above atmospheric pressure throughout the respiratory cycle, even after expiration.
What else does PEEP help prevent?
It also helps prevent alveolar collapse(atelectasis), as might otherwise occur, for instance, in the hypoxia induced shock lung syndrome, where there is a loss of pulmonary surfactant.