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GNURS627/Respiration/Physiology for Anesthesa > Quiz 6 Regulation of Respiration > Flashcards

Quiz 6 Regulation of Respiration Flashcards

1
Q

Where does the most fundamental role in control of breathing take place?

A

Dorsal respiratory group of neurons located in the Medulla Oblongata.

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2
Q

What area of the brain is responsible for sleep?

A

Reticular Activating System (RAS)

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3
Q

Which nerves deliver sensory info to the Dorsal Respiratory Group (DRG)?

A

Glossopharyngeal (IX) and Vagus (X)

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4
Q

What are the 3 sources of peripheral sensory signals that aid in respiration control?

A
  1. Peripheral Chemoreceptors
  2. Baroreceptors
  3. Lung receptors
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5
Q

What does the Dorsal Respiratory Group (DRG) do?

A

Controls inspiration and respiratory rhythm

normal rhythmic breathing

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6
Q

Describe the Inspiratory “Ramp” Signal

A

Motor signal from DRG transmitted to Diaphram

  • Weak signal begins to steadily increase in ‘ramp like’ manner for 2 sec to cause diaphragm contraction (inspiration)
  • excitatory signal abruptly stops for 3 sec for diaphragm relaxation (expiration)
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7
Q

What is the advantage to having the “ramp” signal to the diaphragm?

A

Causes a steady increase in inspiratory volume

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8
Q

What can cause the ramp signal to the diaphragm to increase?

A

exerise

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9
Q

If the ‘ramp’ signal to the diaphram gets shorter (limiting point ceases), what happens to respiration?

A

The inspiration will get shorter -> shortens duration of inspiration -> increased frequency of respiration

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10
Q

What is the function of the Pneumotaxic Center?

A

functions to limit inspiratory phase and secondarily leads to increase rate of breathing.

Controls ‘on/off’ of the inspiratory point & shortens entire respiratory cycle

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11
Q

What will the strength of signal from the Pneumotaxic Center do to respirations?

A

Strong signal - shorter insp phase (0.5 sec) and increased rate (30-40bpm)

Weak signal - long insp phase (5 sec) & reduced rate (3-5 bpm)

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12
Q

What are the 3 groups of neurons that control respiration?

A

Dorsal Resp Group (DRG)
Pneumotaxic Center
Ventral Resp Group (VRG)

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13
Q

When is the Ventral Resp Group stimulation to breath most likely to occur?

A

during exercise - during high levels of pulmonary ventilation

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14
Q

Is the VRG active during normal quiet respirations?

A

No, the DRG is responsible for normal quiet respirations (VRG inactive during this time)

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15
Q

Does VRG contribute to respiratory drive to increase pulmonary ventilation?

A

Yes, it also stimulates abdominal muscles to assist in forced exhalation

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16
Q

What do experts believe the “Apneustic” Center, located in the lower Pons, function to be?

A
  • Signals the DRG to prevent or retard the ‘switch off’ of the inspiratory ramp stimuli
  • works in conjunction with the Pneumotaxic Center to control intensity of inspiration
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17
Q

What is the Hering-Breuer Reflex?

A

Protective feedback reflex which limits the over inflation of the lungs
- Reflex increases the rate of respiration

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18
Q

What is the ultimate goal of respiration?

A

maintain proper concentrations of oxygen, CO2, and hydrogen ions in the tissue

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19
Q

Excess ____________ or ___________ ions in the blood act DIRECTLY on the respiratory center to increase strength of insp and exp motor signals

A

Carbon Dioxde or Hydrogen ions

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20
Q

Does Oxygen have a direct effect on respiratory centers?

A

No. But it does act on peripheral chemoreceptors.

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21
Q

What peripheral chemoreceptors does oxygen work on?

A

Carotid and aortic body chemoreceptors

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22
Q

Where is the chemo-sensitive area of brainstem and what does it respond to?

A

Located in the ventral medulla surface, responds to changes in blood PCO2 and H+ concentration.

23
Q

How does Hydrogen and CO2 stimulate the chemosensitive neurons in the ventral medulla surface?

A

Blood H+ do not cross the blood-brain barrier easily. CO2 believed to stimulate the neurons s/t H+ ion concentration.

CO2 will combine with H2O to form carbonic acid which dissociated will form H+ and bicarb. The released H+ will stimulate the resp center activity.

24
Q

Which has a higher concentration of CO2, the brain or the blood?

A

both are equal since CO2 easily crosses the BBB.

25
Q

After first 1 to 2 days of carbon dioxide exposure the stimulatory respiration response declines to a _______ of the initial response.

A

fifth

26
Q

What causes the decline of the increased CO2 stimulatory response?

A

Renal adjustment of hydrogen concentration back to normal

27
Q

Changes in blood CO2 concentration has potent _____ effect on controlling respiration drive but a weak _______ effect after a few days of adaptation.

A

Acute, Chronic

28
Q

At what level of PCO2 does ventilation greatly increase?

A

35mm Hg

29
Q

Why does O2 NOT have the effect CO2 has on the respiratory center?

A

This is due to the Hemoglobin-oxygen buffer system.

30
Q

What is the Hemoglobin-oxygen buffer system?

A

Deliver normal amounts of O2 to tissues over wide range of pulmonary O2 partial pressures (60mmHG to 1000mmHg).

31
Q

Blood oxygen levels below PO2 of _____mmHg are sensed by peripheral chemoreceptors.

A

70

32
Q

Where are the peripheral chmoreceptors located?

A

CAROTID bodies:

  • bifurcations in common carotid
  • Afferent nerve fibers pass via CN IX to act on DRG

AORTIC bodies:

  • Aortic arch
  • CN X to DRG
33
Q

Stimulation of chemo-receptors is caused by __________ arterial ________ content.

A

decrease, oxygen

34
Q

T/F: Exact means of low PO2 stimulation of nerve endings in carotid & aortic bodies for chemo receptors stimulation is unknown.

A

True

35
Q

If the CO2 and pH remain normal the ventilatory drive by low blood oxygen content is not significant until PO2 falls below _______mmHg.

A

100

36
Q

Loss of sensitivity to CO2 or H ions allows ______ to drive the respiratory center.

A

oxygen

37
Q

What effects alveolar ventilation?

A
  • PCO2
  • pH
  • PO2
38
Q

What does it mean when the curve on the alveolar ventilation curve is displaced to the RIGHT?

A

Higher pH (alkalosis)

39
Q

What does it mean when the curve on the alveolar ventilation curve is displaced to the LEFT?

A

Lower pH (acid)

40
Q

What is measure on the x-axis on the alveolar ventilation curve?

A

PaCO2

41
Q

What is measured on the y-axis on the alveolar ventilation curve?

A

Ventilation L/min

42
Q

What causes increases in ventilation during exercise?

A
  • Brain transmits collateral impulses to brain stem and motor signals to contracting muscles, VRG
  • During exercise the body movements of joint & muscle proprioceptors transmit excitory impulses to respiratory center
  • Hypoxia in muscles during exercise elicits afferent nerve signals to excite respiration center
  • The PCO2 and PO2 changes caused by exercising muscles stimulate respiration
43
Q

T/F: Voluntary control is not mediated through respiratory center.

A

True

44
Q

Describe the pathway in the brain for voluntary control of ventilation.

A

Starts:
Cortex/higher centers –>
cortispinal tract —>
spinal neurons that drive respiratory muscles.

45
Q

What causes a cough?

A

Pulmonary irritant receptors that are found in the epithelium of trachea, bronchi, and bronchioles.

46
Q

Pulmonary irritant receptors may also cause _______ constriction in diseases such as ______ and _________.

A

bronchial, asthma, emphysema

47
Q

What and where are “J receptors” found?

A

sensory nerve endings in alveolar walls

48
Q

What is believe to be the “J receptors” function?

A

Their excitation may give the feeling of dyspnea

49
Q

What occurs to the respiratory center during brain edema?

A

Activity is depressed or inactivated due to decreased blood flow.

50
Q

Name one form of periodic breathing.

A

Cheyne-Stokes breathing

51
Q

T/F: The potential for Cheyne-Stoke breathing is present in everyone.

A

TRUE

52
Q

What are two conditions that allow Cheyne-Stokes breathing?

A
  • Delay in transport of blood from lungs to brain (low CO2)

- Eleveated negative feedback gain (brain damage) due to hypoxia or severe metabolic abnormality.

53
Q

What dampens the mechanism for Cheyne-Stokes breathing?

A
  • Large amounts of dissolved and bound CO2 and O2 in blood and tissue
  • Lungs cannot build-up enough CO2 or deplete O2 supply normally

GNURS627/Respiration/Physiology for Anesthesa (11 decks)

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