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EXCI 259: PHYSIOLOGY > lecture 20: regulation of respiration > Flashcards

lecture 20: regulation of respiration Flashcards

1
Q

true or false: 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

A

true

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2
Q

Rate of alveolar ventilation (VA) is adjusted to what

A

almost
exactly to demands of the body such that PO2 and
PCO2 in arterial blood are hardly ever altered

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3
Q

are the PO2 and PCO2 in arterial blood usually alterned

A

no , usually rate of alverolar ventilationn is adjusted to almost exactly demands of the body

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4
Q

what are the 3 elements involved in regulation of respiration

A
  1. Basic control of respiration
  2. Chemical control of respiration
  3. Peripheral chemoreceptor control of respiration
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5
Q

what are the functions of sensors in terms of regulation of respiration snf give examples

A

– Gather information

– Stretch receptors, peripheral chemoreceptors, baroreceptors, etc

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6
Q

WHAT IS THE FFUNCTIONN OF central controllers in terms of regulation of respiration and give examples

A

– Integrate signals

– Respiratory center (dorsal, ventral, pneumotaxic groups)

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7
Q

what is an example of effectots of regulation of resrpiration

A 
respiratory muscles 
(ex: diaphragm, intercostals)
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8
Q

basic Control of basic rhythm of respiration is generated by what

A

– Generated by the respiratory center (central controller)

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9
Q

where is the respiratory center

A

Mainly in dorsal respiratory group of neurons

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10
Q

true or false; Neurons emits repetitive bursts of inspiratory neuronal action
potentials (cause is unknown)

A

true

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11
Q

explain ramp signal

A

begins weakly (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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12
Q

the neurons part of the respirtory center induce whatt types of discharges and whatt does that mean

A

Induces rhythmical inspiratory discharges (diaphragmatic

contraction)

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13
Q

inhibtion of the excitory signal from the respiratory center does what

A

promotes expiratiton

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14
Q

what are the 2 ways to control inspiratory ramp

A

1) Control of rate of increase of ramp signal

2) Control of limiting point at which ramp
signal suddenly ceases

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15
Q

increased ramp slope promotes what

A

faster fillimng of air Vt in lungs

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16
Q

Early ramp signal cessation shortens or increases duration of inspiration

A

shortens

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17
Q

early ramp signal cessation shortens what

A

shortens duration of inspiration as well as duration of expiration (reason is unclear)
=increased rate (frequency) of breathing

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18
Q

The inherent activity of inspiratory neurons with cell
bodies located in the medulla governs the normal
respiratory cycle how

A

by activating the diaphragm and

intercostal muscles to cause the lungs to inflate

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19
Q

why do the inspirtaory neursons cease firing

A

The inspiratory neurons cease firing because of selflimitations
and inhibitory influence of expiratory
neurons also located in the medulla

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20
Q

as expiration proceeds/elongations, what happens to the inspiratory cetner

A

As expiration proceeds, the inspiratory center becomes
progressively less inhibited and once again becomes
active

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21
Q

the neurons of the respiratory centers are located where and form what

A

in the medully oblongata

from the rhymicity center

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22
Q

what does the rhytmicitt center control

A

automatic breathing

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23
Q

what are the 2 types of neurons in the respiratory center

A

Consists of interacting neurons that fire either during inspiration (I neurons) or
expiration (E neurons)

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24
Q

activation of E neurons inhibit or active the I neurons

A

inhibit

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25
Q

what are the 3 major collections of neurons in the respiratory center

A

1) dorsal respiratory group
2) pneumotaxic center
3) ventral respiratory center

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26
Q

the dorsal respiratory group neurons cause what (inspiration or expirmation)

A

innspiration

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27
Q

where is the dorsal respiratory group of neurons located and what is their sensation

A 
Located in dorsal portion of medulla,
with sensory termination of vagal and
glossopharyngeal sensory nerves,
which transmit signals from peripheral
chemoreceptors, baroreceptors, and
lung receptors
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28
Q

where is the pneumotaxic center neuronns location

A

in the sup portion of the pons

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29
Q

what do the neurons of the pnemotaxic center control and how

A

control breathinng pattern by limitinng duration of filling phase

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30
Q

where are the neuronns of the ventral respiratory group lcated

A

in the ventrtolateral part of the medulla

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31
Q

what is the main function of the neurons in the ventral respiratory group

A

Inactive during normal quiet breathing,
but contributes extra respiratory drive
(especially expiration) when needed

invovled in forced expriationn and innspirtationn

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32
Q

chemical control of respirationn is achieved via what two chemicals

A

co2 and h+

33
Q

true or false: Excess CO2 or H+ in blood acts indirectly on respiratory center itself

A

false

Excess CO2 or H+ in blood can act directly on respiratory center itself

34
Q

Excess CO2 or H+ in blood greatly increases or decrases the strength of both inspiratory and expiratory signals to
respiratory muscles

A

increases

35
Q

Co2 and H+ Greatly increases the strength of (both inspiratory and expiratory) or just expiratory signals to respiratory muscles

A

both

36
Q

at rest, what provudes the most imporatant respiratory stimulus

A

At rest, carbon dioxide pressure in arterial plasma provides the most
important respiratory stimulus

ex: small inncreases in Po2 in inspired air trigger large increases in minute ventilation

37
Q

why do Small increases in PCO2 in inspired air trigger large increases in minute
ventilation

A

because there is a very narror range for PCO2

38
Q

does plasma acidity have an affect over minute ventilation?

A

yes
Plasma acidity, which varies with the blood’s carbon dioxide content,
exerts command over minute ventilation

39
Q

a fall in ph signals and reflects what

A

A fall in blood pH signals acidosis and reflects carbon dioxide retention
and carbonic acid formation

40
Q

what happens to inspiratory activtiy as arterial pH declines and hydrogen ions accumulate

A

As arterial pH declines and hydrogen ions accumulate, inspiratory activity
increases to eliminate carbon dioxide and reduce arterial levels of carbonic
acid

41
Q

which out of these 3 have a direct effect on respiratory center (o2, co2 or h+)

A

co2 and h+

42
Q

which out of these 3 do not have significant direct effect on respiratory center (co2, o2 or H+)

A

o2

43
Q

trtue or false and explain: 02 has a direct effect on respiratory center

A

false: INDIRECT

• Rather acts almost entirely on peripheral chemoreceptors
located in carotid and aortic bodies à these in turn transmit
nervous signals to respiratory center for control of respiration

44
Q

explain how o2 has an indirect effect on the thee respiratory centr

A

• Rather acts almost entirely on peripheral chemoreceptors
located in carotid and aortic bodies à these in turn transmit
nervous signals to respiratory center for control of respiration

45
Q

co2 and H+ directly stimulate what neuronal area

A

chemosensoitive ara located beneath ventral surface of medualla

46
Q

what area is highly sensorite to changes in blood co2 and h+

A

neuronal area called chemosensitive area

47
Q

what does stimulation of the chemosensitve area (area sensitive to co2 and h+) cause and result in

A

Stimulation of this area causes excitation of other portions of respiratory center

• Results in increased rate and depth of breathing

48
Q

sensory neurons in the chemosensotive neuronal area are mosttly stimulated by what

A

h+ ions (versus co2)

49
Q

true or false; H+ ions have difficulty
permeating blood-brain barrier (BBB) and
blood-cerebrospinal fluid (CSF) barrier

A

true

50
Q

explain the reason that altho the chemoreceptive area is more sensotive to H+ ions, blood pco2 actually has a bigger effect

A

becais eH+ ions have difficulty
permeating blood-brain barrier (BBB) and
blood-cerebrospinal fluid (CSF) barrier

51
Q

which has a larger effect in stimulated chemosensotive area: change in blood H+ or change in blood PCo2 and why

A

blood pco2 becuase H+ has a hard time going thru BBB

52
Q

CO2 has less direct effect in stimulating chemosensitive

area or more direct effect than H+ ions

A

less

53
Q

CO2 has less direct effect in stimulating chemosensitive

area than H+ ions , so why does it have a larger effectt in stimulated the chemosensotive area

A

because but easily crosses blood-brain barrier

and blood-cerebrospinal fluid barrier

54
Q

explain the effect of carbon dioxide on chemosensotive area

A

When blood PCO2 increases, PCO2 in interstitial fluid of
medulla and cerebrospinal fluid increases.

CO2 molecules in these fluids bind with H2O to form carbonic acid (H2CO3)

H2CO3 dissociates into H+ and bicarbonate ion (HCO3-)

H+ ions (those dissociating from H2CO3, not the freely
circulating H+ ions outside the BBB) stimulate the sensory
neurons in chemosensitive area.

55
Q

what happens when the lungs become overinflated

A

When lungs become over-inflated, sensory stretch
receptors located in bronchi and bronchioles are activated

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

=hering-breur inflation reflex

56
Q

the hering breur inflation reflex is activated when and what does that prtect you from

A

Hering-Breuer reflex is activated when inflation or tidal

volume (VT) exceeds 1.5 L, i.e. protects lungs from overinflation

57
Q

what are 2 locations of peripheral chemorecpros

A

1) carotid bodies

2) aortic bodies

58
Q

where are the carotid bpdoes located

A

Located bilaterally at

bifurcation of carotid arteries

59
Q

explain the passageway of afferent nerves in the carotid bodies

A

Afferent nerve fibers pass
through Hering’s nerves

=to glossopharyngeal nerve

=to dorsal respiratory center.

60
Q

where are aortic bodies located

A

located along the arch of aorta

61
Q

where do the nerves pass in the aortic boddies

A

Afferent nerve fibers pass
through vagus nerve

= to dorsal respiratory center.

62
Q

true or false: changes in
PCO2 have a tremendous
effect on alveolar ventilation

A

true

63
Q

increases in blood PCO2 within the normal range (35-75) cause what incrase inn alveolar ventilation

A

1 to 8 fold increase

64
Q

does changes in PCO2 or changes in blood pH s there a larger effect on alveolar ventilation

A

PCO@

65
Q

sensitive to reduced oxygen pressures resides where

A

in peripheral chemorecptors

66
Q

The carotid bodies monitors the state of arterial blood where/when

A

just

before it perfuses the brain

67
Q

Decreased arterial PO2 increases

alveolar ventilation through what

A

aortic

and carotid chemoreceptor stimulation

68
Q

decreased arterial PO2 through aortic amnd carotid chemorecptors causes what

A

increase in alveolar ventilation

69
Q

what protects us from reduced oxygen pressure in inspired air

A

the carotid bodies n

70
Q

Peripheral chemoreceptors also stimulate ventilation in

exercise because of what

A

increases in temperature, acidity, and

carbon dioxide and potassium concentrations

71
Q

ADD SLIDES 21 AND 22

A

….

72
Q

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

A

true

73
Q

The indirect effect of CO2 and H+ through chemoreceptors has

the 2 following characteristics compared to their direct effect:

A

1) It is much less powerful (7 times less) than their direct effect on
the respiratory center in the brain. Therefore, their indirect effect is
often neglected.

2) It is much faster (5 times) than the direct effect, so it might play an
important role in increasing the response time to CO2 at the onset
of exercise

74
Q

alveolar ventilation can increase collectively by what 3 factors

A 
– Increased CO2 or PCO2
– Decreased O2 or PO2
– Decreased pH or
increased blood H+
concentration
75
Q

add slide 25/26

A

.

76
Q

after holding your breath for how long does the urge for inspiration come

A

40 s

77
Q

where does the stimulus to breath com from after holding breath

A

The stimulus to breathe comes primarily from increased arterial
PCO2 and H+ concentration

– The breakpoint for breath holding = 50 mm Hg PCO2

78
Q

what does hyperventilating before breath holding do tto PCO2

A

Hyperventilating before breath holding causes alveolar

PCO2 to decrease to 15 mm Hg

79
Q

explain why Hyperventilating before breath holding causes alveolar
PCO2 to decrease to 15 mm Hg

A

– A larger-than-normal quantity of carbon dioxide leaves the blood
and arterial PCO2 decreases

– Extends breath-holding duration until arterial PCO2 and/or H+
concentration cause the urge to breathe

EXCI 259: PHYSIOLOGY (21 decks)

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