RT Cardiopulmonary A&P Ch. 11
What is considered the maximum level of PaO2 on room air at maximal hyperventilation?
130 mm Hg
How much does minute ventilation increase for each 1 mm Hg rise in PaCO2?
2 to 3 L/min
An acute increase in the PaCO2 has an extremely powerful effect on ventilation. How long does it typically take for this effect to weaken?
24 to 48 hours
Arterial hypoxemia does not stimulate ventilation until PO2 reaches which level?
60 mm Hg
Which of the following peripheral chemoreceptors has the greatest influence over the respiratory centers?
Carotid bodies
Which of the following reflexes may be involved in periodic deep sighs and stimulating the first breaths of a newborn baby?
Head's reflex
What is the clinical importance of the periodic deep sighs during quiet breathing?
Help prevent alveolar collapse or atelectasis
Which of the following mechanisms explains ventilatory stimulation caused by hypoxemia in COPD patients with moderate hypoxemia?
Hypoxemia raises the peripheral chemoreceptors' sensitivity to [H+].
Which of the following events are feasible explanations for the oxygen-associated hypercapnia that sometimes affects patients who have severe COPD? I. Hypoxic stimulus removal II. Worsening of V/Q relationships III. As PaO2 increases, the slow reduction in PaCO2 induces hypoventilation. IV. Shunt
I and II
Which of the following are considered effects of stimulation of the motor component of the vagovagal reflexes? I. Bronchoconstriction II. Laryngospasm III. Coughing IV. Bradycardia
I, II, III, and IV
Which of the following statements are true of the DRG? I. It consists mainly of inspiratory neurons. II. It sends impulses to the phrenic and external intercostal motor nerves in the spinal cord. III. It provides the main stimulus for inspiration. IV. These neurons are involved in the Hering-Breuer and Head's reflexes.
I, II, III, and IV
Which of the following conditions stimulate the chemoreceptors? I. Hypercapnia II. Acidemia III. Hypoxia IV. Alkalemia
I, II, and III
Which of the following effects are associated with stimulation of the J-receptors? I. Rapid, shallow breathing II. Sensation of dyspnea III. Expiratory narrowing of the glottis IV. Croup in infants
I, II, and III
Which of the following statements are true of the peripheral chemoreceptors? I. They account for only 20% to 30% of the ventilatory response to hypercapnia. II. Unlike the central chemoreceptors, the carotid bodies are directly exposed to arterial blood. III. The initial ventilatory response to metabolic acidosis is fairly quick. IV. They are the most important mechanisms that respond to hypercapnia.
I, II, and III
Which of the following procedures may elicit vagovagal reflexes? I. Endotracheal intubation II. Airway suctioning III. Administration of aerosol therapy IV. Bronchoscopy
I, II, and IV
Which of the following reflexes is (are) caused by stimulation of the irritant receptors? I. Bronchoconstriction II. Coughing III. Bradypnea IV. Narrowing of the glottis
I, II, and IV
Which of the following statement are true regarding the use of hyperventilation in the management of patients with TBI? I. Hyperventilation is effective for only about 24 to 48 hours. II. Hyperventilating patients with TBI to a PaCO2 less than 30 mm Hg increases the danger of cerebral ischemia. III. Every patient with TBI should be hyperventilated, at least during the first 24 hours. IV. Hyperventilation therapy should be considered only for patients with high ICPs.
I, II, and IV
The inhibitory neurons that switch off the inspiratory ramp arise from which of the following areas? I. VRG II. DRG III. Pulmonary stretch receptors IV. Pneumotaxic center
III and IV
Which of the following is (are) true of the Hering-Breuer reflex? I. It results in an expiratory discharge pattern. II. In adults it is activated only at small tidal volumes. III. It has been suggested to be an important control mechanism in quiet breathing. IV. It is important in regulating the respiratory rate and depth during moderate to strenuous exercise.
IV
Transection of the brainstem between the pons and medulla results in which of the following respiratory patterns?
Irregular breathing pattern
What is the explanation for the minor importance of oxygen in controlling ventilation?
Oxygen molecules have no effect on the medullary chemoreceptors.
What is the primary mechanism that drives ventilation in humans?
PCO2
Stimulation of which of the following receptors explains the stimulation of ventilation after the splashing of cold water on the skin?
Peripheral proprioceptors
Which of the following conditions produces the strongest stimulation of the J-receptors?
Pneumonia
Which of the following respiratory centers controls the length of inspiration?
Pneumotaxic
Which of the following statements describes apneusis?
Prolonged inspiratory gasps interrupted by occasional expirations
Which of the following conditions will elicit the strongest Hering-Breuer reflex?
Pulmonary fibrosis
Which of the following patterns describes Cheyne-Stokes breathing?
Respiratory rate and tidal volume gradually increase and then gradually decrease to complete apnea. Then the tidal volume and breathing frequency gradually increase again.
When stimulated, the stretch receptors will have which of the following effects on respiration?
Stop further inspiration
What is the explanation for the lack of ventilatory stimulation when anemia and hypoxemia are present?
The carotid bodies respond to decreased PO2 rather than to an actual decrease in CaO2.
Why are COPD patients with chronic hypercapnia unable to hyperventilate to decrease their PaCO2?
The central chemoreceptors respond to [H+], not the CO2 molecule.
What is the explanation for the suppression of the ventilatory stimulus present in subjects chronically exposed to high altitudes?
The exposure of central chemoreceptors to an alkaline environment
Which of the following describes Biot's breathing?
The respiratory rate gradually increases and then gradually decreases to complete apnea but tidal volume has essentially the same depth. Then the breathing frequency gradually increases again.
