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Physiology - Pulmonary > Regulation of Ventilation > Flashcards

Regulation of Ventilation Flashcards

1
Q

What does Dr. Rosen say is the most important regulator?

A

The Bicarb Buffer

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2
Q

Equation for equilibrium constant?

A

K = [(H3O)(A-)]/[(HA)(H2O)

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3
Q

Equation for dissociation constant?

A

K = [(H+)(A-)]/(HA)

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4
Q

Henderson-Hasselbach equation?

A

pH = pK + log [(A-)/(HA)]

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5
Q

The ability of buffers to minimize fluctuations in pH depnds primarily on….

A

pK of the buffer relative to pH of body fluids

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6
Q

When (A-)=(HA), pH=

A

pK

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7
Q

When pH=pK, buffering capacity is…

A

maximal

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8
Q

Most commonly utilized physiological buffer?

A

HCO3

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9
Q

log 1 =

A

0

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10
Q

Is Hb a big deal in buffering?

A

Yes. RBC proteins have approx. 60% buffering

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11
Q

If pK = 6.1 and pH = 7.4, then why is the bicarbonate system so great anyway?

A

The ratio of HCO3/CO2 is kept fairly constant by breathing. Everything goes to shit if you quit breathing.

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12
Q

On an acid added vs. pH chart, where is pK?

A

The middle

Review on Pg. 9-3

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13
Q

What happens to ventilation/Bicarb system in COPD

A

Elasticity of the lung is lost. Incomplete exhalation.

Retained CO2 -> Lowered pH -> Respiratory Acidosis

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14
Q

What happens to ventilation/Bicarb system in hyperventilation?

A

CO2 is blown off -> pH Increases –> Respiratory Alkalosis

Risk of Stopped breathing/Seizure

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15
Q

What is the primary factor in respiratory control?

A

CO2. When it is decreased, respirations slow and could even stop.

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16
Q

Nervous signals of the voluntary respiratory control system?

A

Cerebral Cortex –Corticospinal Tracts–> Respiratory Motoneurons

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17
Q

Functions of the voluntary control system of ventilation?

A

Speech, Voluntary Breath Holding, Fear, Pain

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18
Q

What do the neurons of the pons and medulla do in the autonomic control system of ventilation?

A

Generate rhythmic, patterned excitatory output to muscle groups of inspiratory or expiratory muscles.

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19
Q

Where are lower motor neuron cell bodies of the autonomic control system located?

A

Phrenic Motor Nucleus (C3-5)

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20
Q

Transection below the medulla will…

A

stop breathing completely.

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21
Q

Transection above the medulla will…

A

not affect breathing greatly

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22
Q

What is a Central Pattern Generator?

A

A group of neurons capable of rhythmic patterned output in the absence of outside influence or sensory feedback.

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23
Q

Role of the dorsal respiratory group in breathing?

A

Primary stimulus for inspiration.

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24
Q

Where does the dorsal respiratory group receive input from? (4)

A

Central and Peripheral Chemoreceptors
Pulmonary Stretch Receptors
Somatic Pain Receptors
Mechanoreceptors

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25
Q

Phrenic nerve activity during inspiration?

A

Activity increases in rate and number of units discharging (recruitment)

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26
Q

What does the increase in phrenic activity cause?

A

Recruitment of more muscle fibers.

More motor units = Bigger Tidal Volume

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27
Q

What terminated inspiration?

A

Natural CPG rhythm modulated by sensory feedback.

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28
Q

Is expiration or inspiration primarily passive?

A

expiration

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29
Q

Role of Ventral Respiratory Group in respiration?

A

Contains inspiratory (mostly accessory muscles) and expiratory neurons.

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30
Q

Transection at inferior pons causes…

Why?

A

Sustained gasping breathing.

Unregulated output of apneuistic center.

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31
Q

Who normally regulates the apneuistic center?

A

Pneumotaxic Center in superior pons.

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32
Q

Cutting at the inferior pons will cause…

A

Prolonged Inspiration

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33
Q

What is the Hering-Breuer Reflex?

A

Vagal feedback from stretch receptors of the lungs inhibit inspiration

34
Q

BIG PICTURE -
In breathing, medulla is there for …
pons/vagus are there for…

A

Sustaining Patterned Breathing

Fine Tuning/Feedback

35
Q

Where are the carotid bodies located? Aortic Bodies?

A

The bifurcation of the common carotids.

Near the aortic Arch.

36
Q

What are type I cells of the islands called?

A

Glomus

37
Q

Afferents from the carotid body go to the ______ via the _____.

A

Medulla. Glossopharyngeal.

38
Q

Afferents from the aortic bodies go to the _______ via the ______

A

Medulla. Vagus.

39
Q

Conduction speed of fibers returning to the medulla from the CB?

A

7-12 m/sec

40
Q

Per gram, what is the most vascular structure in the body?

A

Carotid Body

41
Q

Carotid/Aortic bodies increase their discharge when…

A

pH drops

42
Q

Effect of Carotid/Aortic body stimulation?

A

Increased Rate and Tidal Volume (and thus overall ventilation).

43
Q

Carotid bodies account for __% of the ventilatory drive. Losing them causes a ____% loss in response to CO2

A

20

30

44
Q

What goes with a loss of carotid bodies?

A

Compensatory ventilatory response to hypoxia

45
Q

Influence of which is more important – Carotid or Aortic Bodies?

A

Carotid

46
Q

Hypercapnea =

A

Elevated CO2 in the Blood

47
Q

Maximum receptor activity is at ______

A

Low Po2 values

48
Q

For Carotid Body, High pH will cause…

Low pH will cause…

A

Less Firing

More Firing

49
Q

Where are central chemoreceptors located?

A

Ventral Medulla

Near CN VI-X+XII

50
Q

What do central chemoreceptors sense changes in? (medium)

A

CSF

51
Q

Why is CO2 in this region comparable to the blood?

A

Close proximity to choroid lexus

High Blood Flow

52
Q

How does H+ get into the CSF?

A

CO2 crosses BBB
Hydrated to H2CO3
Dissociates to HCO3 and H+

53
Q

What happens with acidosis of the CSF?

A

Increased Tidal Volume

54
Q

Why does the CO2 matter to central receptors

A

As an intermediate to make H+

CO2 has very little effect without pH change

55
Q

Central receptors respond ____ to H+ and _______ to CO2

A

Directly

Indirectly

56
Q

How does adaption occur?

A

Compensatory transport of HCO3- across BBB via Cl- anion exchanger

57
Q

Example of a patient in which adaption would occur

A

A patient with obstructive lung disease would return to normal breathing despite high CO2

58
Q

What is the primary driver of ventilation for post-adaption patients?

A

PO2

59
Q

Respiratory Acid-Base control interacts at times with _______

A

Metabolic acid-base conditions

60
Q

Metabolic Acidosis is….

It will cause….

A

Accumulation of ketone acids in diabetes

Respiratory Stimulation -> Hyperventilation -> Increase in Blood pH

61
Q

Metabolic alkalosos cause…

It will cause….

A

Lots o vomiting

Depressed ventilation -> Inc. in CO2 -> Drop in Blood pH

62
Q

When metabolism increases, pCO2….

So What

A

Rises

Causes inc. ventilation

63
Q

Alveolar PCO2 and ventilation have a nearly _______ relationship.

A

Linear

64
Q

What causes a change in the linear relationship of alveolar PCO2 and ventilation?

A

When PCO2 of inspired air comes near alveolar, CO2 elimination becomes difficult

65
Q

Inhaled CO2 above 7% can lead to…

A

Spike in PCO2
CNS Depression
CO2 narcosis + Coma

66
Q

Relationship of PO2 and ventilation rate?

A

PO2 must drop significantly before ventilation is affected.

67
Q

How low must PO2 drop before significant change is noted?

A

60 mm Hg

68
Q

What happens in carbon monoxide poisoning?

A

CO binds Hb –> Carboxyhemoglobin

Binding of CO to one of the 4 causes retained O2 at other sites and no release.

69
Q

What happens to the Ox dissociation curve in CO poisoning?

A

To the Left

70
Q

Name three nonchemical influences on ventilation.

A

Proprioceptors and Stretch Receptors
Irritant Receptors
Other Pulmonary Receptors

71
Q

Where are proprioceptor/stretch receptors located?

Stim ventilation in response to…

A 
Muscles/Tendons/Joints
Physical Disturbance (Slap/Tickle) and possibly in anticipation of exercise
72
Q

What stimulates irritant receptors

A

Chemical Irritants
Mechanical Irritants
Histamine and Bradykinin

73
Q

Effect of irritant receptors on trachea/bronchi? Receptors of the lungs?

A

Receptors of trachea and bronchi – coughing

Receptors of lungs – Rapid shallow breathing and bronchoconstriction.

74
Q

Stretch receptors in the smooth muscle of the airways….

A

Excites sensory neurons of the vagus –> Inhibiting Resp.

75
Q

When does the Hering-Breuer reflex turn on in adults?

A

Tidal Volumes Above 1 Liter

Very Strenuous Exercise

76
Q

Deflation receptors stimulate….

A

rapid, shallow breathing.

77
Q

Deflation receptors may contribute to ventilatory response to…

A

Pulmonary Congestion or Edema

78
Q

What is the Reticular Activating System?

A

A diffuse group of neurons in the midbrain/medulla that contributes to many autonomic functions.

79
Q

Two now familiar components of the Reticular Activating System?

A

DRG and VRG

80
Q

Off switch neurons are ________ for most of inspiration, but over time….

A

Inhibited.

inhibition decreases until respiration can be terminated.

81
Q

Symptom Rosen loved using to describe ALKALOSIS

Secondary symptom he also seemed to like

A

Tingling around the fingers/mouth

Dry Mouth

82
Q

What happens in a tonic seizure?

A

Extremities go stiff

Physiology - Pulmonary (5 decks)

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