Microsoft PowerPoint - 05-Respiration-3-yu-for international students.ppt [兼容模式].pdf

Respiratory regulation

1. Regulationofrespiration Regulationofrespiration Regulation

of

respiration Regulation

of

respiration
„„
Breathing is controlled by the central Breathing is controlled by the central neuronal network to meet the metabolic neuronal network to meet the metabolic ddfthbd ddfthbd d
eman
d
s o
f

th
e
b
o
d
y
d
eman
d
s o
f

th
e
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o
d
y
Neuralregulation Neuralregulation
– –
Neural

regulation

Neural

regulation

– –
Chemicalregulation Chemicalregulation Chemical

regulation Chemical

regulation

2. Respiratorycenter Respiratorycenter Respiratory

center Respiratory

center
„„
Definition: Definition:
– –A collection of functionally similar neurons A collection of functionally similar neurons
that help to regulate the respiratory movement that help to regulate the respiratory movement

3. Respiratorycenter Respiratorycenter Respiratory

center Respiratory

center
„„
Medulla Medulla P P
Basic respiratory center: produce
and control the respiratory
„„
P
ons
P
ons
„ „
Higherrespiratorycenter: Higherrespiratorycenter:
cerebralcortex cerebralcortex
rhythm
„ „
Higher

respiratory

center: Higher

respiratory

center:
cerebral

cortex
,
cerebral

cortex
,
h
ypot
h
a
la
m
us

&
lim
b
ic

syste
m h
ypot
h
a
la
m
us

&
lim
b
ic

syste
m
ypot aa us& bcsyste ypot aa us& bcsyste
„ „
S
p
inal cord: motor neurons S
p
inal cord: motor neurons
p p

4. Neuralregulationofrespiration Neuralregulationofrespiration Neural

regulation

of

respiration Neural

regulation

of

respiration
„„
Voluntary breathing center Voluntary breathing center
– –Cerebral cortex Cerebral cortex
„ „
Automatic (involuntary) breathing center Automatic (involuntary) breathing center
– –Medulla Medulla – –PonsPons

6. Neural generation of rhythmical Neural generation of rhythmical
breathing breathing
The discharge of
medullary inspiratory
neuronsprovides rhythmic
input to the motor neurons
innervating the inspiratory
muscles. Then the action
ttil th
po
t
en
ti
a
l cease,
th
e
inspiratory muscles relax,
andexpirationoccursas and

expiration

occurs

as

the elastic lungs recoil.

7. „„
Inspiratory Inspiratory neurons neurons neurons neurons
„ „
Ex
p
irator
y
Ex
p
irator
y

py py
neurons neurons

8. Respiratorycenter Respiratorycenter Respiratory

center Respiratory

center
„„
Dorsal respiratory group Dorsal respiratory group(medulla) (medulla)
– –
mainly mainly
causes ins
p
iration causes ins
p
iration
p p
„ „
Ventral respiratory group Ventral respiratory group(medulla) (medulla) ––causes causes
ith iti i iti ith iti i iti
e
ith
er exp
ira
ti
on or
insp
ira
ti
on e
ith
er exp
ira
ti
on or
insp
ira
ti
on
„ „
Pneumotaxic cente
r
Pneumotaxic cente
r
(
u
pp
er
p
ons
)

(
u
pp
er
p
ons
)

– –
inhibits inhibits
(pp p ) (pp p )
apneustic center & inhibits inspiration,helps apneustic center & inhibits inspiration,helps controltherateandpatternofbreathing controltherateandpatternofbreathing control

the

rate

and

pattern

of

breathing control

the

rate

and

pattern

of

breathing
„ „
Apneustic center Apneustic center(lower pons) (lower pons) ––to promote to promote inspiration inspiration

10. Hering-Breuer inflation reflex
(Pulmonary stretch reflex)
„
The reflex is originated in the lungs and
di t db th fib fth
me
di
a
t
e
d

b
y
th
e
fib
ers o
f

th
e vagus nerve:
–
Pulmonary
inflation
reflex
:
Pulmonary

inflation

reflex
:
ƒinflation of the lungs, eliciting expiration.
–Pulmonary inflation reflex:
ƒ
deflation stimulatinginspiration
ƒ
deflation
,
stimulating

inspiration
.

11. Pulmonary
inflation
reflex
Pulmonary

inflation

reflex
„
Inflation of the lungs →+pulmonary stretch receptor→+vagus nerve→- medually inspiratory neurons→ +
elicitinge piration
+
eliciting

e
x
piration

13. Chemicalcontrolofrespiration Chemicalcontrolofrespiration Chemical

control

of

respiration Chemical

control

of

respiration
„„
Chemoreceptors Chemoreceptors
– –Central chemoreceptors: Central chemoreceptors:medulla medulla
ƒ ƒ
Stimulated by [H Stimulated by [H
+ +
] ]
↑ ↑
in the CSF in the CSF
ƒ ƒ
Stimulated

by

[H Stimulated

by

[H
] ]
↑ ↑
in

the

CSF in

the

CSF
– –Peripheral chemoreceptors Peripheral chemoreceptors
ƒ ƒCarotid body Carotid body
↓ ↓
↑ ↑
– –
Stimulated by arterial Stimulated by arterial
PO PO
2 2
↓ ↓
or or
[H [H
+ +
] ]
↑ ↑
ƒ ƒAortic body Aortic body

14. Centralchemoreceptors Central

chemoreceptors

15. Peripheralchemoreceptors Peripheralchemoreceptors Peripheral

chemoreceptors Peripheral

chemoreceptors
Chemosensory neurons thatrespondtochanges that

respond

to

changes
in blood pH and gas
content are located in
the aorta and in the carotid sinuses; these sensory afferent neurons alter CNS
lti f
regu
la
ti
on o
f

the rate of ventilation.

18. Effect of carbon dioxide on Effect of carbon dioxide on
lili lili
pu
lmonary vent
il
at
ion pu
lmonary vent
il
at
ion
Smallchangesinthe Small

changes

in

the
carbon dioxide content ofthebloodquickly of

the

blood

quickly

trigger changes in
ventilationrate ventilation

rate
.
CO
2
↑
→↑respiratory activity

19. Central and peripheral chemosensoryneurons chemosensory

neurons

that respond to increased
carbon dioxide levels in
the blood are also stimulated by the acidity fromcarbonicacid so from

carbonic

acid
,
so

they “inform” the
ventilation control center
in the medulla to increase the rate of ventilation.
COCO
+H+H
OO
→
HH
COCO
→
HH
++
+HCO +HCO
33
--
CO CO
2 2
+H +H
2 2
O O
→
H H
2 2
CO CO
3 3
→
H H
+ +
+HCO +HCO
3 3

20. Effect of hydrogen ion on Effect of hydrogen ion on
lili lili
pu
lmonary vent
il
at
ion pu
lmonary vent
il
at
ion
[H
+
] ↑→↑respiratory activity
Regardless of the source, of

the

source,
increases in
the acidity of
th bl d th
e
bl
oo
d
cause
hyperventilation.

21. Regardless of the source,
increases in the acidit
y
of
y
the blood cause hyperventilation, even if carbon dioxide levels are driven to abnormally low llleve
ls.

22. Effect of low arterial PO Effect of low arterial PO
2 2
on on
lili lili
pu
lmonary vent
il
at
ion pu
lmonary vent
il
at
ion
PO
2
↓→↑respiratory activity
Aseverereductioninthearterialconcentrationof A

severe

reduction

in

the

arterial

concentration

of

oxygen in the blood can stimulate hyperventilation.

23. Chemosensoryneurons Chemosensory

neurons
that respond to decreased
oxygen levels in the blood
“inform” the ventilation control center in the
dllti th t
me
d
u
ll
a
t
o
increase
th
e ra
t
e
of ventilation.

24. In summary: In

summary:
The levels of oxygen carbon oxygen
,
carbon
dioxide, and hydrogenions hydrogen

ions
in blood and CSF
provide information
that alters the rate of ventilation.

25. Regulationofrespiration Regulationofrespiration Regulation

of

respiration Regulation

of

respiration