Lecture 6: Breathing control and sleep apnea

Question 1

Dyspnea is the sensation of…

Answer 1

A high ventilatory drive

Question 2

What cell group controls inspiration?

Answer 2

Dorsal respiratory group (brainstem)

Question 3

What does the Pre-Botzinger complex due?

Answer 3

Respiratory pace maker

Question 4

Two broad groups that control ventilatory drive

Answer 4

Chemoreceptors and lung receptors

Question 5

Central chemoreceptors respond to…Where is it?

Answer 5

CO2 (measure of low pH) –> breath out; brain side of BBB in medulla

Question 6

Carotid body and aortic body are termed what kind of chemoreceptors and what do they respond to?

Answer 6

Peripheral; O2

Question 7

What do we do in response to an elevated CO2? What is this called (________ drive)?

Answer 7

Increase minute ventilation RAPIDLY; hypercapnic drive

Question 8

Describe the hypoxic drive

Answer 8

Non-linear, small, often no drive untill close to LOC (35 torr)

Question 9

Is the hypoxic drive clinically relevant?

Answer 9

Not really, people can be very hypoxic with little dyspnea

Question 10

Four types of lung receptors…what do these cause?

Answer 10

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

Question 11

Drowsy EEG (awake, drowsy)

Answer 11

Alpha waves

Question 12

Stage 1 EEG

Answer 12

Theta waves

Question 13

Stage 2 EEG

Answer 13

Sleep spindles, K complexes (half your night here)

Question 14

Stage 3 EEG

Answer 14

Delta waves (20-25% your night here)

Question 15

REM sleep

Answer 15

Low voltage, like awake

Question 16

What happens to your CO2 on transition to sleep?

Answer 16

Rises (2-6 torr)

Question 17

What happens to breathing in REM?

Answer 17

Decreased ventilatory drive, dependence on diaphragmatic function, decreased muscle tone (including breathing muscles)

Question 18

Definition of obstructive sleep apnea and symptoms

Answer 18

Respiratory pauses for at least 10 sec, 5+ times per hour of sleep; snoring and sleepiness

Question 19

What is obstructive sleep apnea a risk for?

Answer 19

MI, stroke, CHF

Question 20

Causes of ventilatory drive (central) sleep apnea (5)

Answer 20

Morbid obesity, Ondine’s Curse (congenital central hypoventilation syndrome), medications (narcotics), brain problem, heart failure

Question 21

Gene of central congenital hypoventilation

Answer 21

PHOX2b gene

Question 22

During obstructive sleep apnea, are you trying to breath? Then what’s happening

Answer 22

Yes! Upper airways muscles normally contract to keep airway open but sleep –> decreased muscular activity

Question 23

What do we call respiratory pattern in central sleep apnea

Answer 23

Cheyne-Stokes Respiration = periodic breathing

Question 24

What happens to our arterial blood gases at end of max exercise?

Answer 24

No change

Question 25

Exercise means…

Answer 25

Increasing O2 consumption (15 x resting)

Question 26

Equation for O2 consumption…how can we increase this?

Answer 26

VO2 = Qt (cardiac output) (CaO2 - CvO2); raise Qt, increase CaO2, reduce CvO2

Question 27

Can we increase CaO2?

Answer 27

Not really, only by increasing hemoglobin or arterial oxygen content (but we’re already close to 100%)

Question 28

What do we primarily due during exercise? (3)

Answer 28

1. 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)

Question 29

What happens to blood pH during exercise?

Answer 29

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)

Question 30

During exercise, how do we increase CO?

Answer 30

Acutely –> heart rate, over time –> stroke volume