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Physiology > Respiratory V Control of Respiration > Flashcards

Respiratory V Control of Respiration Flashcards

1
Q

what is the ultimate goal of respiration

A

to maintain proper concentrations of O2, CO2 and H+ in the tissues

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2
Q

what brain tracts act in respiratory system

A

corticospinal tract act on muscles of breathing and ventrolateral tract

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3
Q

what do chemoreceptors respond to

A

only H+

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4
Q

what do peripheral chemoreceptors respond to

A

H+ , O2 and CO2

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5
Q

what are the only receptors that sense O2

A

peripheral receptors

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6
Q

what do excess CO2 and H+ do to respiratory centers

A

activates them to increase alveolar ventilation

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7
Q

what does decreased O2 do to alveolar ventilation

A

increases it

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8
Q

how does decreased O2 impact central respiratory centers

A

indirectly by acting on peripheral chemoreceptors that relay the signal to the central respiratory center

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9
Q

what are the 2 basic controls of breathing

A

-voluntary: corticospinal tract
- automatic: ventrolateral tract

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10
Q

describe the corticospinal tract

A

involves descending input form the thalamus and cerebral cortex, can bypass the respiratory control centers in pons and medulla

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11
Q

when is the corticospinal tract activated

A

during talking, sneezing, singing, swallowing, coughing, defecation, anxiety, fear

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12
Q

what is the ventrolateral tract sensitive to

A

-primarily controlled by changes in PCO2
- less sensitive to PO2 and H+

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13
Q

where are the receptors for the ventrolateral tract control located

A

pulmonary mechanical receptors

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14
Q

where is the ventrolateral tract located

A

activated by respiratory centers in the pons and medulla such as DRG and VRG

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15
Q

what two areas in the brainstem control respiration

A

-medullary respiratory centers
-pontine respiratory group

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16
Q

what makes up the medullary respiratory centers

A

-dorsal respiratory group (DRG)
- ventral respiratory group (VRG)

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17
Q

what make sup the pontine respiratory group

A

-pneumotaxic center
-apneustic center

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18
Q

where is the DRG located

A

in the nucleus of the tractus solitarius (NLS)

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19
Q

is the DRG involved in inspiration or expiration

A

inspiration

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20
Q

what neurons does the DRG receive afferent input from and what specific types of neurons are they

A

CN 9 (a peripheral chemoreceptor) and 10 (peripheral chemoreceptor and mechanoreceptor)

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21
Q

what type of stimulus does the DRG supply to what?

A

excitatory inspiratory stimuli to phrenic motor neurons

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22
Q

what does the DRG mainly do

A

set the basic rhythm for breathing by setting the frequency of inspiration - central pattern generator

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23
Q

describe the signal pattern sent by the DRG

A

signal begins weakly, increases steadily for 2 seconds, then will abruptly cease for ~3 seconds before resuming the cycle of 12-20 breaths for minute

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24
Q

what types of receptors does the DRG contain and what do they do when activated

A

-opiate receptors
- when activated inhibit respiration and decrease sensitivity to changes in PCO2

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25
Q

where is the VRG located

A

nucleus ambiguus and nuclues retroambiguus

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26
Q

is the VRG involved in inspiration or expiration

A

mostly expiration

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27
Q

are the neurons in the VRG active during normal breathing

A

no

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28
Q

when are neurons in the VRG activated

A

when forceful expiration is required

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29
Q

what does the VRG control motor neurons for

A
  • expiratory muscles such as abdominals and internal intercostals
  • accessory inspiratory muscles
  • group of neurons in the pre-botzinger complex that have respiratory pacemaker control
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30
Q

what are the pontine respiratory centers

A

-pneumotaxic center
- apneustic center

31
Q

what does the pneumotaxic center do when activated

A

shortens the time of inspiration

32
Q

what is the relationship between the pneumotaxic center and the apneustic center

A

they are antagonists of each other

33
Q

what does the apneustic center do when activated

A

causes excitation of the DRG which results in prolonged inspiration with brief periods of expiration

34
Q

what is the summary of brainstem control of breathing

A

-afferent information regulates the activity of the medullary inspiratory center (DRG) via central and peripheral chemoreceptors and mechanoreceptors (lung stretch and muscle/joint receptors)

35
Q

what are the respiratory reflexes that are sensitive to mechanical stimuli and what are the functions of each

A
  • hering-breuer reflex (achieve optimal rate and depth)
  • irritant receptors (protective)
  • J receptors (Function unclear)
  • joint and muscle proprioceptors
36
Q

describe how the herin-breuer reflex works, what causes it, and the result

A
  • stretch receptors in bronchi and bronchioles are activated when the lungs over stretch.
  • to activate this reflex tidal volume must increase more than 3 times
  • result: stops further inspiration and decreases rate
37
Q

where are irritant receptors located, what are they stimulated by and what is the result

A
  • located between epithelial cells in conducting zone
  • stimulated by noxious exogenous substances, endogenous agents, and mechanical stimulation
    -result: rapid, shallow breathing, coughing, sneezing
38
Q

where are J receptors located, what are they stimulated by and what is the result

A
  • located in alveolar walls next to capillaries
  • stimulated by alveolar inflammatory processes (pneumonia), pulmonary vascular congestion (CHF) and edema
  • result: rapid, shallow breathing and a sensation of dyspnea
39
Q

what are joint and muscle proprioceptors sensitive to and what is the result

A
  • sensitive to change in position and muscle movements not metabolism
  • result: increase activity of DRG to increase rate of breathing
40
Q

what is the purpose of joint and muscle proprioceptors

A

-automatically adjusts to load imposed by decreased lung compliance or increased airway resistance (weighted blanket)
- stimulate ventilation by slapping skin, cold water etc

41
Q

what receptors are most important for minute to minute breathing

A

central chemoreceptors

42
Q

where are central chemoreceptors located and what do they do when activated

A

-located on ventral surface of medulla
- activation of these stimulate the DRG

43
Q

what are central chemoreceptors sensitive to

A

pH of CSF or in other words H+

44
Q

what is a drop in CSF pH is reflective of

A

a higher than normal amount of PCO2

45
Q

what happens when CSF [H+] increases

A

increase in respiratory volume and rate

46
Q

does arterial [H+] activate central chemoreceptors

A

no

47
Q

what is the mechanism of central chemoreceptors

A

-CO2 is permeable to the blood brain barrier
- in the CSF, CO2 is converted to H+ and HCO3- via carbonic anhydrase
- the H+ produced in the CSF activates the central chemoreceptors which stimulates the DRG

48
Q

is the effect of a change in CO2 potent acutely or chronically

A

acutely

49
Q

when are central chemoreceptors most effective and why

A

within 1-2 days because during and after that time period the kidneys will have begun to compensate and reabsorb HCO3- and HCO3- has slowly diffused through the blood brain barrier and CSF barriers will buffer H+

50
Q

what is a danger for patients with chronic respiratory problems

A

the kidney and buffer mechanisms compensate for the elevated PaCO2 and H+ so that they no longer stimulate the medullary respiratory centers
- then the peripheral chemoreceptors become critical for respiratory control

51
Q

where are peripheral chemoreceptors located

A

in the aortic bodies and carotid bodies

52
Q

what nerves are located in each body where the peripheral chemoreceptors are located

A
  • glossopharyngeal from the carotid bodies
  • vagus from the aortic bodies
53
Q

what are peripheral chemoreceptors sensitive to in arterial blood

A
  • low PaO2, high PaCO2 and low pH
54
Q

what happens to alveolar ventilation at PaO2 less than 60 mmHG

A

LARGE increase in alveolar ventilation

55
Q

wwhy do PaO2 levels have to fall below 60 mmHg to have an effect on respiratory function

A

very sharp drop in Hb saturation so decreased ability to transport O2 to the tissues

56
Q

what do increases in PaCO2 do to aortic and carotid bodies

A

increase the rateof firing of both of them

57
Q

which response is more powerful to changes in PaCO2: peripheral chemoreceptor or central

A

central

58
Q

which response is faster to changes in PaCO2 and by how much: peripheral chemoreceptor or central

A

-peripheral chemoreceptor by 5 times

59
Q

what does decreased arterial pH affect the rate of

A

increase the rate of carotid bodies

60
Q

how does hypoxia affect the response to PaCO2

A

it enhances it

61
Q

after what pressure does PaCO2 stimulate an increase in alveolar respiration

A

after 35mmHg

62
Q

which affects alveolar ventilation more easily: pH or CO2

A

CO2

63
Q

what does metabolic acidosis do to PaCO2 response

A

enhance it

64
Q

what decreases response to PaCO2

A

sleep, opiods, narcotics, chronic obstruction, and deep anesthesia

65
Q

what do most inhaled anesthetics cause and how

A

respiratory depression by inhibiting the DRG and abolish the response to hypoxemia and hypercarbia (increased CO2)

66
Q

what is the effect of NO on respiratory rate

A

increases respiratory rate and decreases tidal volume so there is minimal change in minute ventilation and PaCO2 levels

67
Q

what does NO do to hypoxic drive

A

decreases it

68
Q

what does NO do to PVR

A

increases it and decreases perfusion

69
Q

what does NO do to the NS

A

mild activator of SNS

70
Q

breathing is _____ controlled during sleep

A

less rigorously

71
Q

what percentage of men and women have obstructive sleep apnea

A

4% and 2% women

72
Q

what percentage of people with obstructive sleep apnea are undiagnosed

A

85%

73
Q

what happens during obstructive sleep apnea

A

-when asleep the tone of the throat and tonuge muscles that maintain the opening of the ororpharynx decreases

Physiology (41 decks)

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