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PHYL 4504 > Control of Breathing > Flashcards

Control of Breathing Flashcards

1
Q

what are the three elements of respiratory control?

A

Sensors, Central controller, Effectors

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2
Q

WHat do sensors do?

A

gather information and feed it up

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3
Q

What does the central controller in the brian do

A

coordinates informaiton and sends inpulses down

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4
Q

What does the effectors do?

A

affect ventilation (respiratory muscle)

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5
Q

in the medulla: dorsal respiratory group (DRG)

A

nucleus tractus solitarius - recieved afferent input from 9th and 10th cranial nerves

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6
Q

in the medulla - ventral respiratory group (VRG)

A

rostral nucleus retrofacialis, caudal nucleus retroambiguus, nucleus paraambiguus, contains both inspiratory and expiratory neurons

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7
Q

Inspiration begins with _____

A

increased discharge from cells in nucleus tractus solitarius, nucleus retroambiguus and nucleus paraambiguus - leads to contraction of respiratory muscles

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8
Q

at the end of inspiration -

A

decrease in neuronal diring results in relaxation of respiratory muscles = exhalation

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9
Q

Basic rhythm of respiration is set by

A

DRG

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10
Q

DRG mainly causes

A

inspiration

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11
Q

VRG mainly causes

A

expiration

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12
Q

Pneumotaxic area is in the ____ and mainly controls ___ and _____

A

superior pons…. rate and depth of breathing

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13
Q

during normal respiration, nervous signals start ___ and then ____ steadily

A

weakly and increase steadily - ramps up for 2 seconds - inspiration

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14
Q

nervous signal ceases for next 3 seconds, which turns off the excitation to the diaphraghm which permits…

A

elastic recoil of chest wall and lungs = expiration, cycle repeats

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15
Q

a ramp allows what?

A

steady increase in volume of lungs rather than a sudden gasp

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16
Q

inspiratory ramp input can be controlled by

A

increase rapidly so lungs can fill rapidly…

limit point at which ramp suddenly turns off - increases the ventilatory frequency

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17
Q

Pneumotaxic area is located…

A

dorsally in the nucelus parabrachialis of upperpons

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18
Q

pneumotaxic area send inputs to..

A

inspiratory area

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19
Q

pneumotaxic area controls the..

A

switch off point of respiratory ramp, so controlling the duration of the filling phase of the breathing cycle

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20
Q

when pneumotaxic signal is strong…

A

inspiration is short

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21
Q

when signal is weak

A

inspiration last longer, overfilling the lungs

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22
Q

the function of the pneumotaxic area is to

A

limit inspiration and so regulate inspiratory volume

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23
Q

secondary effect on pneumotaxic area is to

A

increase breahting rate - limiting inspiration also shortens expiration, so frequency increases

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24
Q

penumotaxic area may also_ ______ the respiratory rhythm because a normal rhythm can exist in its absence

A

fine tune

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25
Q

What other factors affect respiration

A

cortex, pulmonary mechanoreceptors

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26
Q

the cortex can override the brainstem to a point how does this affect PaCO2

A

hyperventilation decreases PaCO2 resulting in alkalosis - hypoventilation results in changes

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27
Q

pulmonary mechanoreceptors - herring breuer inspiratory inhibitory reflex

A

stimulated by increases in lung volumes, especially those associated with increases in ventilatory rate and tidal volume

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28
Q

herring breuer inspiratory inhibitory reflex

A

stretch reflex mediated by vagal fibres, and results in cessation of inspiration by activation of “off” neurons in medulla. Inactive during quiet breahting - important in newborns

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29
Q

Diving reflex

A

cold water stimulates nasal or facial receptors to stop breathing (apnea) which protects against aspiration of water

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30
Q

Sneeze reflex

A

receptors in nose

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31
Q

aspiration or sniff reflex

A

stimulation of mechanical receptors in nasopharynx and pharynx. strong short duration inspiratory effort that moves material from nasopharynx to pharync, swallowed

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32
Q

hering breuer inflation reflex..

A

inspiratory inhibitory reflex that arises from afferent sretch receptors located in ASM - reflex effect is to slow respiration via increase in expiratory time, becomes activated when tidal volume exceeds 1500mL (vagal nerve),negative feedback mechanism

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33
Q

what are the three sensory receptors in the tracheobronchial tree that respond to stimuli to affect aspects of pulmonary physiology?

A

Irritant receptors, slowly adapting pulmonary stretch receptors, and juxta-alveolar capillary (J) receptors

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34
Q

Irritant receptors

A

rapidly adapting pulmonary stretch receptors: stimulated by inhaled dust, noxious gas and cigarette smoke

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35
Q

where are irritant receptors located?

A

in trachea and large airways - located between epithelial cells lining airways - transmit information via myelinated vagal afferent fibres

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36
Q

Stimulation of irritant receptors results in

A

increase in airway resistance via reflex constriction stimulation, activated musce, reflex apnea and cough

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37
Q

slowly adapting pulmonary stretch receptors respond to

A

mechanical stimulation, activated by lung inflation

38
Q

slowly adapting pulmonary stretch receptors transmit information via

A

myelinated vagal afferent fibres

39
Q

Juxta-alveolar capillary receptors are located

A

in alveolar walls, near capillary bed

40
Q

J receptors are activated by

A

engorgement of pulmonary capilaries with blood and increases in interstitial fluid volume - results in an increased breathing rate

41
Q

J receptors mediate the change in ___

A

breathing pattern, inducing rapid, shallow breathing a sensation of dyspnea

42
Q

Joint and muscle receptors

A

mechanoreceptors in joints and muscles that detect movement of limbs and instruct the inspiratory centre to increase breathing rate - important in the early response to exercise (annticipatory)

43
Q

What is dyspnea?

A

Subjective feeling of shortness of breath

44
Q

Sensors - Chemoreceptors are located where?

A

peripheral - carotid and aortic bodies

45
Q

What to chemoreceptors do?

A

trasmit afferent information to central resp control centre - only chemoreceptor that responds to changes in PO2 - repsonsible for 40% of ventilatory response to CO2 - small and highly vascularized structures

46
Q

Chemoreceptors are made up of what cells?

A

type 1 (glomus) cells - rich in mitochondria and ER and cytoplasmic granules containing NTs DA, ACh, NE and neuropeptides

47
Q

What to type 1 glomus cells sense

A

PO2, PCO2 and pH - respond to arterial levels, not venous

48
Q

What are chemoreceptors stimulated by?

A

decrease PO2, increase H+, increase PCO2

49
Q

There is a _____ response to PO2

A

non-linear

50
Q

Stimulated to increase breathing rate for what 3 things

A

significantly decreased PO2 (hypoxia) - less than 60mmH, decrease arterial pH (metabolic acidosis) - resp compensation- independent of changes in arterial PCO2 and mediated by carotid bodies, increase PCO2 (resp acidosis) - less inportant response, but rapid and useful in matching ventilation to abrubpt changes in PCO2

51
Q

What happens if response to arterial PO2 is not present

A

severe hypoxemia may depress ventilation - ex: bilateral carotid body resection - complete loss of hypoxic ventilatory drive

52
Q

people exposed to chronic hypoxia develop ___

A

carotid body hypertrophy

53
Q

Chemoreceptors - central - on the ventral surface of the medulla respond to

A

directly to changes in the pH of CSF and indirectly to changes in arterial PCO2

54
Q

decrease in pH leads to

A

increased breathing rate

55
Q

what are the most important receptors involved in minute to minute control of ventilation

A

central chemoreceptors

56
Q

central chemoreceptors are surrounded by

A

brain ECF - composition of ECF governed by CDF, local bood flow, and metabolism

57
Q

CSF deperated from blood by

A

Blood brain barrier - impermeable to H+ and HCO3-, but not CO2

58
Q

As blood pH increases, CO2 does what?

A

diffuses into CSF and H+ ions are generated

59
Q

Normal CDF pH =

A

7.32

60
Q

CSF contains less _____ so it has less ____ capacity

A

proteins, buffering

61
Q

What is the most important factor for control of ventilation

A

PCO2 arterial - very sensitive - held within 3mmHg

62
Q

Ventilatory response to PCO2 is reduced by

A

sleep, increasing age, exercise tolerance, barbituates

63
Q

Increased depth and rate of ventilation due to

A

central chemoreceptors and peripheral chemoreceptors

64
Q

PaCO2 greater than 100mmHg is a respiratory ___

A

depressant

65
Q

Ventilation increases rapidly when PCO2 increases, what does lowering PO2 do

A

ventilation is higher and slope is steeper

66
Q

Alveolar PO2 can fall to ___ before increased ventilaiton occurs

A

50mmHg

67
Q

increasing PCO2 ____ ventilation at an PO2

A

increases

68
Q

When PCO2 increases, a PO2 less than 100 mmHg causes

A

some stimulation of ventilation via peripheral chemoreceptors

69
Q

when you increase PCO2 and breath a hypoxic gas mixture, ventilation ____

A

increases more rapidly

70
Q

patients with compensated metabolic acidosis have lower pH and low PCO2 show

A

increased ventilation (reduced PCO2)

71
Q

OSA

A

obstructive sleep apnea

72
Q

apnea results in

A

significant decreases in PO2 and increases in PCO2

73
Q

most common type of sleep apnea

A

OSA

74
Q

when does OSA occur?

A

when the upper airway (hypopharynx) closes during inspiration

75
Q

OSA is similar but more severe than ___

A

snoring

76
Q

Airway is ____ and airflow___

A

totally obstructed, stops

77
Q

X and Y also occur in OSA

A

hypercapnia and hypoxemia

78
Q

Pleural pressure osciallations ____ as CO2 rises

A

increases

79
Q

resistance to airflow is very ____ as a result of the upper airway obstruction

A

high

80
Q

Risk factors for OSA

A

age, male, obesity, increased neck circumference, alcohol and sedative use, weight gain and craniofacial abormalities

81
Q

Symptoms of OSA

A

daytime sleepiness, restless sleep, morning dry mouth and headaches, mod changes, snoring, nocturnal chocking and cardiac arrhythmia, erythorcytemia

82
Q

Treatment for OSA

A

CPAP, dental appliances, surgery

83
Q

Central sleep apnea is characterized by

A

breathing that stops and starts during sleep

84
Q

CSA occurs when

A

CNS drive to the ventilatory muscles transiently stops

85
Q

What is the difference between OSA and CSA

A

lack of resp effort in CSA

86
Q

Causes of CSA

A

damage to central resp areas or abnormalities of the neruomuscular aparatus, high altitude

87
Q

Repeated epidosed of apnea during which patient makes ___

A

no resp effort

88
Q

no attempt to breath demonstrated by ___

A

lack of oscilations in pleural pressure

89
Q

Breathing pattern - when remove sensory input from lungs

A

cycle is lengthened and tidal volume increased so alveolar ventilation is not affected

90
Q

Apneustic breathing

A

input from cerebral cortex and thalamus eliminated with vagal block = loss of resp inhibition activity results in loss of inspiratory drive = prolonged inspiration activity broken after several second by brief expiration (apneusis)

91
Q

Cheynes Stokes breathing

A

abrnormality of ventilatory control, varying tidal volume and centilatory frequency - after apnea, VT and resp frequency increase over several breaths, then decrease until another apnea

92
Q

What changes in blood gas occur in cheynes stokes breathing

A

increase PACO2 decrease PAO2

PHYL 4504 (8 decks)

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