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73 Cards in this Set

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How long is the normal sleep-wake cycle in humans?
90 min
How many stages compose the normal sleep-wake cycle in humans?
6
What 6 stages make up the sleep wake cycle?
1. Four stages of NREM sleep
2. Period of REM
3. Period of arousal
How many sleep-wake cycles do we have per night?
4-5
What happens to the sleepwake cycle as the night progresses?
It becomes shorter.
What stages of sleep are Slow Wave Sleep?
Stages 3/4 of NREM sleep.
What technique is used to measure breathing patterns during wakefulness and NREM sleep?
Respiratory inductance plethysmography (RIP)
What does RIP measure?
-Chest wall excursion
-Abdominal wall excursion
How does RIP measure excursion?
By converting changes in electrical inductance of elastic bands that encircle the rib cage and abdomen into vol measurmnts
What is the breathing pattern during wakefulness like?
Regular except for intermittent sighs.
What is the function of a sigh?
To open up alveoli that have collapsed - alleviates atelectasis.
What stages of NREM sleep are most irregular? Regular?
1/2 = irregular

3/4 = VERY REGULAR
What do we call the breathing pattern in NREM stages 1/2?
Periodic breathing
How does breathing change during REM sleep?
It becomes CHAOTIC and IRREGULAR
What happens to ribcage and abdomen excursion in REM sleep?
They become discoordinated.
What does an electrooculogram show?
Eye movement
What does an electrooculogram show during REM sleep?
phasic rapid eye movements
What is paradoxical respiration?
When the rib cage moves inward when the abdomen moves outward.
When is ventilation the highest?
Wakefulness
In what stage of sleeping is ventilation the highest?
REM
In which stage is ventilation higher; NREM 2 or 4?
2
What is central apnea?
Cessation of all airflow and respiratory muscle activity due to failure of the rythm generator
What respiratory mechanisms fail as a result of rythm generator failure?
-All airflow ceases
-All respiratory muscle activity fails
What happens to the chest wall and abdomen during apnea?
They are motionless
What happens to nasal and oral airflows during apnea?
They are absent
Why does central apnea occur?
We don't know
Is central apnea fatal? Why?
No - because the carotid chemoreceptors will sense the increase in PCO2 and decreased PO2 and stimulate breathing.
What is a hypothesis about patients with central apnea?
They are adults who escaped SIDS as children.
What is obstructive sleep apnea?
Cessation of airflow in spite of sustained activity of resp pump muscles.
How does data from a patient with obstructive sleep apnea differ from a pt with central apnea?
Obstructive apnea will still have chestwall and abdominal motion during the apnea.
What happens to nasal and oral airflow in a pt with obstructive sleep apnea (OSA)
They cease.
Are abdominal and chestwall movements normal during obstructive sleep apnea?
No; they become paradoxical
What happens to hemoglobin saturation of O2 during obstr. sleep apnea?
It declines
Where is the site of obstruction in OSA?
Pharynx
What obstructs the airway in OSA?
The tongue
What causes the tongue to obstruct the pharynx?
Loss of rhythmic and tonic genioglossus muscle activity
What happens as a result of genioglossus inactivity?
Tidal volume is nearly abolished.
During what phase of sleep does this genioglossus failure and decline of tidal volume occur?
During phasic eye movements of REM sleep - even in normal individuals.
What are the 3 breathing abnormalities during sleep?
1. Central apnea
2. Obstructive apnea
3. Cheyne-stokes breathing
What is the hallmark of Cheyne-Stokes respiration?
Alternating periods of hyperpnea and apnea
What do respiration patterns look like in cheyne-stokes?
Waxing and waning in crescendo - decrescendo patterns.
Which phase is longer in cheyne-stokes?
Hyperpneic phases > apneic
What is a postulated cause of Cheyne-Stokes breathing?
An increased gain in carotid chemoreceptors causing over correction of small fluctuations in arterial blood gases.
In what 3 conditions does Cheyne stokes breathing occur?
-Unstable sleep states
-Initial few days at hi altitude
-Heart failure patients
What are 3 initial defense mechanisms to pathogens and pollutants trying to enter the lungs?
1. Filtration in the vasooropharynx and airways
2. Sneezing/coughing
3. Mucociliary clearance
What 3 immune mechanisms work if pathogens do make it into alveoli?
1. Surfactant
2. Opsonins
3. Macrophages/neutrophils
What component of surfactant allows it to work as an immune defense?
Proteins SP-A and SP-D
What do proteins SP-B and SP-C do?
Reduce surface tension
How do proteins SPA and SPD work?
To minimize inflammatory reactions - tho they are still going on - to reduce injury to the alveoli.
What reflexes are activated by nasal receptors?
1. Sneeze
2. Diving reflex
What reflex is stimulated by Epipharyngeal receptors?
Aspiration
What reflex is stimulated by pharyngeal receptors?
Swallowing
What 2 reflexes are stimulated by laryngeal receptors?
-Cough
-Apnea
3 types of receptors in the lungs:
1. C-fiber endings
2. Slowly adapting receptors
3. Rapidly adapting receptors
6 things stimulated by C-fiber endings:
1. Pulmonary chemoreflex
2. Rapid shallow breathing
3. Bronchoconstriction
4. Mucus secretion
5. Bradycardia
6. Hypotension
4 things stimulated by slowly adapting receptors:
1. Hering-bruer inflation reflex
2. Hering-bruer deflation reflex
3. Bronchodilation
4. Tachycardia
4 things stimulated by Rapidly adapting receptors:
1. Hering-bruer deflation reflex
2. Cough
3. Bronchoconstriction
4. Mucus secretion
What is the Epipharyngeal Aspiration reflex intended for?
To dislodge material in the pharynx so you can swallow it.
What stimulates the Epipharyngeal aspiration reflex?
Tapping the epipharynx
What is the result of stimulating the epipharynx?
Brief, Strong Inspiratory Efforts
What illustrates the brief strong inspiratory efforts?
Increases in phrenic nerve activity.
What is the function of the Laryngeal apneic response?
To protect you from inhaling water injected into the larynx.
What happens when laryngeal receptors are stimulated by water injection?
A prolonged expiratory period
What illustrates the prolonged expiratory period?
Absence of phrenic nerve activity.
What happens to slowly and rapidly adapting receptors as the lung is filled and tracheal pressure increases?
-Slowly adapting receptors fire continuously until inhalation is inhibited
-Rapidly adapting receptors respond initially only
What is the function of rapidly adapting receptors?
Irritant receptors for triggering coughing.
What happens to the time of onset of inspiration if you occlude the trachea at FRC?
nothing
What will happen if you occlude the trachea after inhaling one tidal volume?
The lungs will continue to inflate(steady lung inflation) and to prevent overfilling, Pes (esophag pressure) will NOT change b/c u no longer want to inhale; expiratory duration will be enhanced.
How is the enhanced expiration duration illustrated?
Esophageal pressure shows no negative deflections, so no inspiratory muscle contraction; only passive expiratory work.
What is the reflex that prolongs the expiratory duration during tracheal occlusion at FRC?
The Hering-Bruer Inflation reflex
Why is it called an inflation reflex if the expiration duration is enhanced?
Because it's the reflex to STOP inhalation - protective against pneumothorax; otherwise we'd all just keep inhaling and never stop.
How is the Hering-Bruer deflation reflex achieved?
By removing 100 mL of gas from the lungs at FRC and occluding the trachea.
What happens to the lungs in response to deflation?
The expiratory duration is shortened.