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EXCI 357 Pulmonary Physiology > 7. Regulation of Respiration > Flashcards

7. Regulation of Respiration Flashcards

1
Q

What is the Rate of alveolar ventilation (VA) adjusted to meet?

A

Rate of alveolar ventilation (VA) is adjusted almost exactly to demands of the body such that PO2 and PCO2 in arterial blood are hardly ever altered.

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2
Q

What are the Elements involved in the regulation of respiration?

A
  1. Basic control of respiration
  2. Chemical control of respiration ( Direct effect on the resp. system)
  3. Peripheral chemoreceptor control of respiration
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3
Q

a. What induces the basic rhythm of respiration?

b. What promotes Expiration?

A

a. Neurons emits repetitive bursts of inspiratory neuronal action potentials
Induces rhythmical inspiratory discharges

b. Inhibition of this excitatory signal promotes expiration

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4
Q

True or false. the Central controller of rythm control of respiration is located mainly in the ventral respiratory group of neurons?

A

False. Mainly in dorsal respiratory group of neurons

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5
Q

True or false. The nervous signal transmitted to inspiratory muscles is done so instantaneously.

A

False. Begins weakly (with low frequency of impulses) - >impulse frequency increases gradually in a ramp manner for 2 seconds, which results in gradual expansion of lungs and chest -> excitation then suddenly ceases for next 3 seconds, so that elastic recoil of lung occurs for expiration

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6
Q

What is the advantage of ramp signaling?

A

It allows a steady increase in volume of lungs during inspiration

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7
Q

What are the two ways to control inspiratory ramp?

A
  1. Control of rate of increase of ramp signal (slope of ramp)
  2. Control of limiting point at which ramp signal suddenly ceases Delays ramp signal
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8
Q

Would Increasing or decreasing the ramp slope promote faster filling of air (VT) into lungs

A

Increasing

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9
Q

True or false VT is proportional the slope of Ramp (signaling)

A

True. Increases in slope increase VT

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10
Q

How would an early ramp signal cessation affect breathing freuency, breathing duration, VT and RV?

A

Decrease duration of breath (thereby decreasing VT?), which would cause a compensatory increase in breathing frequency

No change in RV

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11
Q

The respritory center is composed of several groups of neurons located ______ in the ________ and _____ of brain stem

A

bilaterally
medulla oblongata
pons

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12
Q

The respiratory center is divided in how many collections of neurons?What are they called?

A
  1. Dorsal respiratory group
    Pneumotaxic center
    Ventral respiratory group
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13
Q

a .Which collection of neurons Causes expiration* &

b. inspiration. Where are they located?

A

a .Ventral respiratory group

b .Located in ventrolateral part of medulla

  • forced expiration
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14
Q

What does Pneumotaxic center control and where is it located?

A

Controls breathing pattern

Located in superior portion of pons

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15
Q

What does the Dorsal respiratory group control and where is it located?

A

Mainly causes inspiration

Located in dorsal portion of medulla

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16
Q

The vagal and glossopharngeal nerves transmit sensory signals into respiratory center from which sensory receptors?

A

Peripheral chemoreceptors

Baroreceptors

Various lung receptors

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17
Q

Which neuronal center’s main function is to limit inspiration?

A

Pneumotaxic Center

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18
Q

Which center controls peak “switch-off “* point of inspiratory ramp signal

A

Pneumotaxic Center.
Thereby controls duration of filling phase in lung cycle
-> controls air volume inspired into lungs (VT)

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19
Q

True or false. Strong pneumotaxic signal shortens duration of inspiration

A

True.

This results in small filling of air in lungs

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20
Q

True or false. Weak pneumotaxic signal results in prolonged duration of filling phase

A

True.

21
Q

What would cause excess air inspired

A

Weak pneumotaxic signal resulting in aprolonged duration of filling phase

22
Q

What would cause excess air inspired

A

Weak pneumotaxic signal resulting in a prolonged duration of filling phase

23
Q

This group of neurons:
- Remains totally inactive during normal quiet respiration

  • Does not seem involved in basic rhythmical breathing
A

Ventral Group

24
Q

True or false. When respiratory drive for -> VE becomes greater than normal, respiratory signals from the dorsal respiratory group spill over into the ventral respiratory group -> ventral group then contributes extra respiratory drive

A

True.
Can contribute to both inspiration and expiration, but are especially important in providing powerful expiratory signals when high VE is needed

25
Q

Under some conditions, this center sends signals to dorsal respiratory group to prevent or delay “switch-off” of inspiratory ramp signal causing….

A

Apneustic Center

Causing prolonged inspiration to fill the air fully into lungs and very short expiratory gasps

26
Q

What is the The Hering-Breuer Inflation Reflex

A

prevention of over inflation

27
Q

How is the The Hering-Breuer Inflation Reflex initiated and carried though?

A

Afferent sensory signals from stretch receptors feed back to dorsal respiratory group through vagus nerve -> “switch off” inspiratory ramp signal -> inspiration ceases

28
Q

If VT exceeds ___ Hering-Breuer reflex is activated

A

1.5L

29
Q

Ultimate goal of chemical control of respiration?

A

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

30
Q

True or false. In general Excess CO2 or H+ in blood mainly act directly on respiratory center itself

A

True

31
Q

Does O2 have a direct or indirect effect on on respiratory center of brain in controlling respiration?

A

Indirect.
Acts almost entirely on peripheral chemoreceptors located in carotid and aortic bodies –> these in turn transmit nervous signals to respiratory center for control of respiration

32
Q

Which ions can directly stimulate a neuronal area called chemosensitive area.

b where is this area located?

c. Stimulation of this area causes excitation of …. ? Resulting in?

A

CO2 and H

b. located beneath ventral surface of medulla

c other portions of respiratory center.
- Resulting in increased rate and depth of breathing

33
Q

True or false. CO2 has a greater effect on H+ on the Chemosensitive areas in the brain?

A

False. H+ does, however changes in blood H+ has little effect compared changes in blood CO2 b/c H+ has a very difficult time crossing the brain.

34
Q

Does CO2 have a direct effect on the chomesensitive areas?

A

Indirect

35
Q

How does CO2 stimulate the chomesensitive areas

A

When blood CO@ levels increases , PCO2 in interstitial fluid of medulla and cerebrospinal fluid increases.
Binds to H2O and forms carbonic acid
Splits into H+ and bicarbonate ion
–> The H+ ions then stimulate the chemosenstive areas

36
Q

Anything past an increase of ____mmHg of PCO2 has tremendous effect on VA.

A

40mmHg

37
Q

Caratid chemoreceptors pass through which series of nerves to signal the Dorsal Resp. center
- What does it detect?

A

Herrings -> glossopharngeal

  • Changes in PO2
  • > Well placed to minimize fr of adjusments
38
Q

Aortic chemoreceptors pass through which series of nerves to signal the Dorsal Resp. center
- What does it detect?

A

Just vagus

  • Changes in PO2
  • > Well placed to minimize fr of adjusments
39
Q

True or false.Chemotaxic receptors are located where the blood saturation of said chemical would normally be the lowest. Why is this so?

A

False. Chemotaxic receptors are located where the blood saturation of said chemical would normally be the highest.

-> In order to avoid constant adjustments

40
Q

As PaO2 decreases there’s an ______ response in caratid chemotaxic receptors

A

Increases.

-> due their being located in an area of normally highly saturated in O2

41
Q

Give the CB impulse for the following PaO2’s

  • 95 mmHg
  • 50 mmHg
  • 300 mmHg
A

Normal PaO2 = 95 mmHg : CB imp ~ 160-175
.
- 50 mmHg ( LOW)
- CB impulses ~ 400 (massive impulse)

  • 300 mmHg ( High)
    -> CB impulses ~ 75
    ( Lower than normal impulse)
42
Q

True or false Increase of CO2 and H+ also excites chemoreceptors and causes indirect effect on respiratory center?

A

True.

43
Q

True or false. The indirect effect of CO2 and H+ through chemoreceptors has the following characteristics comparing to their direct effect
- It is much less powerful (7 times less) than their direct effect on the respiratory center in the brain.

  • It is much faster (5 times) than their direct effect
A

True.

44
Q

The following PaO2s would effect VA how?

  1. 100 and above
  2. Bellow 100
  3. 60
  4. 20
A
  1. close to no affect
  2. Slightly increasing
  3. 2 times normal VA
  4. 6 times normal VA
45
Q

Which factors would cause an increase in VA?

A
  1. Increased CO2 or PCO2
  2. Decreased O2 or PO2
  3. Decreased pH or increased blood H+ concentration
46
Q

A 20-fold increase in CO2 output and O2 uptake is can be seen in?

A

Strenuous exercise

47
Q

During strenuous exercise , ventilation rate (both VE and VA) increases almost exactly in step with increased _______ while Arterial PO2, PCO2 and pH usually ___________

A

O2 consumption

remain almost exactly normal

48
Q

What causes the increased ventilation during the onset of exercise and beyond the first few seconds of exercise?

A

At the onset of exercise, increase ventilation likely results from neurogenic signals transmitted directly to respiratory center.

Beyond the first few seconds of exercise, chemical factors contribute to the elevation and maintenance of VA

EXCI 357 Pulmonary Physiology (7 decks)

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