Regulation of Respiration Flashcards

1
Q

In the lung where would you find the most compliant alveoli?

A

base

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2
Q

In the lung, where would you find the lowest arterial BLOOD pressure?

A

apex

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3
Q

Optimal gas exchange occurs when ventilation is matched to perfusion

A

awesome

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4
Q

Ventilation to perfusion ratio at the apex is

A

3.3

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5
Q

ventilation to perfusion ratio at the base is

A

0.6

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6
Q

V/Q ratio is highest at the apex, therefore,

A

the apex is “over ventilated and under perfused”

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7
Q

PAO2 difference between apex and base

A

apex is 132 mmHg and base is 89 mmHg

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8
Q

PACO2 difference between apex and base

A

apex is 28 mmHg and base is 42 mmHg

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9
Q

difference in O2 in at apex and base

A

apex is 4 ml/min and base is 60 ml/min

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10
Q

difference in CO2 out at apex and base

A

apex is 8 ml/min and base is 39 ml/min

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11
Q

The apex has high PAO2 because

A

all ventilation and no perfusion so O2 is accumulating in the lung due to the high V/Q ratio and no perfusion is moving it away throughout the body

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12
Q

Where in the lung would you find the lowest PACO2?

A

apex

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13
Q

where in the lung would you find the lowest PAO2?

A

base

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14
Q

where in the lung would you find the highest O2 uptake?

A

base

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15
Q

blood leaving the lung has a PaO2 slightly less than PAO2

A

due to V/Q mismatch and shunting

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16
Q

Control of Respiration

A
  1. respiratory muscles require neural stimulation for contraction
  2. brain establishes the breathing rhythm and force of contraction
  3. changes in ventilation are assessed by feedback sensors which adjust neural output
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17
Q

Medullary Respiratory Centers:
A. Regulate rhythmicity
B. Activate respiratory muscles
C. Three regulatory regions such as —>

A
  1. DRG
  2. VRG
  3. Pre-Botzinger
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18
Q

DRG

A

dorsal diaphragm
primary inspiratory neurons that synapse with motor neurons for inspiration

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19
Q

VRG

A

insp and exp neurons active with forced breathing
maximal exercise (VICTORY)

20
Q

Pre-botzinger

A

respiratory rhythm generation (BPM)

21
Q

Pontine Respiratory Centers

A

A. Located in pons
B. two regulatory regions.
1. apneustic center
2. Pneumotaxic center

22
Q

Pontine Respiratory Centers:
1. Apneustic Center

A

prolongs inspiration by activating neurons in the pre-botzinger complex apneusis: sustained contraction

23
Q

Pontine Respiratory Centers:
2. pneumotaxic center

A

halts inspiration by sending inhibitory signals to the apneustic center and pre-botzinger complex

24
Q

Respiratory Control Centers:
Cortex

A

A. voluntary: modifies respiration for speech, yawning, coughing or breath holding
B. respiratory reflexes will over ride voluntary actions

25
Q

Respiratory Control Centers:
Limbic system and hypothalamus

A

A. regulate emotional responses
B. control breathing patterns during emotional states

26
Q

what region of brain is responsible for voluntary rates of ventilation?

A

cortex

27
Q

what region of brain is responsible for inspiration at rest?

A

dorsal respiratory group

28
Q

what region of brain is responsible for maximal ventilation

A

ventral respiratory group

29
Q

what region of brain is responsible for rate of ventilation?

A

pro-botzinger complex

30
Q

During quiet expiration,

A

there is no AP bc it is passive

31
Q

As ventilation increases until maximum ventilation with forced expiration,

A

the increased frequency of nerve signals creates bigger contractions

32
Q

Peripheral chemoreceptors:
Arterial chemoreceptors
detect changes in?
location?
regulate?

A

A. detect changes in PaO2, PaCO2, and pH
B. primary sensitivity is to changes in PaO2
C. location: carotid artery and aortic arch
D. do not regulate minute-to-minute changes
E. emergency response for very low PaO2 levels
F. do not respond to changes in O2 content

33
Q

Central Chemoreceptors:
regulate?
found?
sensitive?
permeable?

A
  1. central chemoreceptors regulate minute-to-minute ventilation
  2. found within the medulla near the VPG
  3. very sensitive to PCO2 and H+
  4. BBB is permeable to CO2
34
Q

A major factor that quickly influences ventilation is:
pH of arterial blood
arterial PCO2
arterial PO2
arterial bicarbonate conc.

A

arterial PCO2

35
Q

Lung (pulmonary) receptors:
1. pulmonary stretch receptors
found?
prevents?

A

A. found within smooth muscle of lung airways
B. stretching of lung induces activation of receptors which send inhibitory signals to the medullary centers
C. negative feedback mechanism prevents over-inflation
D. active when tidal volumes are high during max. exercise

36
Q

Lung (pulmonary) receptors:
2. irritant receptors
found?
mechanism?

A

a. found in airway epithelial cells
b. noxious gas, duct, and cold air can activate receptors which leads to bronchoconstriction and rapid shallow breathing = protective mechanism limiting exposure
c. irritant receptors may play a role in asthma
d. activation of receptors can induce sneezing or coughing
e. mechanical stimulation during intubation can lead to laryngeal spasm

37
Q

Lung (pulmonary) receptors:
3. pulmonary C fibers

A

a. near alveolar capillaries
b. stimulated by interstitial edema which activates the J reflex that leads to laryngeal closure, apnea, followed by rapid shallow breathing
c. may be responsible for rapid breathing seen in patients with pulmonary: emboli, edema, or pneumonia
d. may also be responsible for feeling short of breath in patients with congestive heart failure

38
Q

Other Respiratory Receptors:

A
  1. nose and nasal passages
  2. upper airways: contain irritant receptors
  3. joint and muscle receptors: give feedback to medullary centers and to increase ventilation
39
Q

the pneumotaxic center and stretch receptors will
a. inhibit neurons in the apneustic center
b. cause contraction of the diaphragm
c. activate internal intercostal nerves
d. cause respiratory arrest, then shallow breathing

A

a

40
Q

EXAM QUESTION
what stimulates the highest rate of ventilation?

A

low O2 and high CO2

41
Q

what is the most important variable regulating ventilation?

A

PCO2 and usually maintained within 3 mmHg

42
Q

responses to changes in PO2 are greater with

A

hypercapnia

43
Q

responses to changes in PCO2 are greater with

A

hypocapnia

44
Q

Hyperventilation

A

decrease PCO2 and increase PO2 result in respiratory alkalosis
low PCO2 is hypocapnia

45
Q

Hypoventilation

A

increase PCO2 and decrease PO2 result in respiratory acidosis
high PCO2 = hypercapnia