Lecture 6: Breathing control and sleep apnea Flashcards
Dyspnea is the sensation of…
A high ventilatory drive
What cell group controls inspiration?
Dorsal respiratory group (brainstem)
What does the Pre-Botzinger complex due?
Respiratory pace maker
Two broad groups that control ventilatory drive
Chemoreceptors and lung receptors
Central chemoreceptors respond to…Where is it?
CO2 (measure of low pH) –> breath out; brain side of BBB in medulla
Carotid body and aortic body are termed what kind of chemoreceptors and what do they respond to?
Peripheral; O2
What do we do in response to an elevated CO2? What is this called (________ drive)?
Increase minute ventilation RAPIDLY; hypercapnic drive
Describe the hypoxic drive
Non-linear, small, often no drive untill close to LOC (35 torr)
Is the hypoxic drive clinically relevant?
Not really, people can be very hypoxic with little dyspnea
Four types of lung receptors…what do these cause?
Stretch (stress in airways), J receptors (stretch in blood vessels), nociceptors (inhale nasty things), chest wall; lead to shortness of breath w/ normal lung gases
Drowsy EEG (awake, drowsy)
Alpha waves
Stage 1 EEG
Theta waves
Stage 2 EEG
Sleep spindles, K complexes (half your night here)
Stage 3 EEG
Delta waves (20-25% your night here)
REM sleep
Low voltage, like awake
What happens to your CO2 on transition to sleep?
Rises (2-6 torr)
What happens to breathing in REM?
Decreased ventilatory drive, dependence on diaphragmatic function, decreased muscle tone (including breathing muscles)
Definition of obstructive sleep apnea and symptoms
Respiratory pauses for at least 10 sec, 5+ times per hour of sleep; snoring and sleepiness
What is obstructive sleep apnea a risk for?
MI, stroke, CHF
Causes of ventilatory drive (central) sleep apnea (5)
Morbid obesity, Ondine’s Curse (congenital central hypoventilation syndrome), medications (narcotics), brain problem, heart failure
Gene of central congenital hypoventilation
PHOX2b gene
During obstructive sleep apnea, are you trying to breath? Then what’s happening
Yes! Upper airways muscles normally contract to keep airway open but sleep –> decreased muscular activity
What do we call respiratory pattern in central sleep apnea
Cheyne-Stokes Respiration = periodic breathing
What happens to our arterial blood gases at end of max exercise?
No change
Exercise means…
Increasing O2 consumption (15 x resting)
Equation for O2 consumption…how can we increase this?
VO2 = Qt (cardiac output) (CaO2 - CvO2); raise Qt, increase CaO2, reduce CvO2
Can we increase CaO2?
Not really, only by increasing hemoglobin or arterial oxygen content (but we’re already close to 100%)
What do we primarily due during exercise? (3)
- Increase minute ventilation via respiratory and tidal volume; 2. Improve V/Q matching (zone 1) via increased blood flow; 3. Increase muscle O2 extraction (shunt blood away from other places)
What happens to blood pH during exercise?
Decreases due to increased CO2 production from lactate metabolism (anaerobic threshold = point when we make lactate, creating CO2, which means we have to breath more)
During exercise, how do we increase CO?
Acutely –> heart rate, over time –> stroke volume
