Human and Animal Physiology; Respiration
Lecture 2
May, 2009
Regulation of Respiration
ƒWhere does the rhythmical activity
originate?
ƒHow is it generated?
ƒHow is the rate and depth of
respiration controlled?
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
1
Human and Animal Physiology; Respiration
Lecture 2
May, 2009
中
脑
NPBM
脑
桥
延
髓
脊
髓
2009/5/8
迷走神经 切断迷走
完整
神经
Copyright:Yingyu Sun-CLOS,BNU
PBKF
?
DRG
VRG
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
2
Human and Animal Physiology; Respiration
Lecture 2
May, 2009
中脑
呼吸调整中枢
脑桥上
脑桥下
（+）
（+）
中枢吸气发生器 （+） 吸气切
断机制
吸气神经元
（－）
延髓
（+）
脊髓
（+）
吸气肌运动神经元
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
吸气
Regulation of Respiration
Sensors
Stretch receptors
Chemoreceptors
Centers
Spinal cord
Medulla
Pons
Cortex
Vagus N.
Phrenic
Ph
i N
N.
Intercostal N.
Effectors
2009/5/8
Respiratory
muscles
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
3
Human and Animal Physiology; Respiration
Lecture 2
May, 2009
Regulation of Respiration
1.Respiratory centers
ƒSpinal cord
ƒMedulla Automatic respiratory rhythm
DRG(dorsal respiratory group), VRG(ventral ~)
ƒPons Pneumotaxic center PBKF (NPBM-KF)
ƒCortex Voluntary control
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
Regulation of Respiration
2.Respiratory reflex
ƒPulmonary stretch reflex(Hering-Breuer reflex)
Inflation reflex:
Deflation reflex:
ƒRegulation by chemical factors
ƒPeripheral chemoreceptors
Carotid bodies
PO2, PCO2, pH
Aortic bodies
ƒCentral chemoreceptors
pH(c.s.f.) PCO2
Ventral surface of the medulla
ƒEffects of CO2 ,O2 on breathing
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
4
Human and Animal Physiology; Respiration
Lecture 2
May, 2009
PO2↓
PCO2↑
[H+] ↑
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
Central
chemoreceptor
DRG
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
5
Human and Animal Physiology; Respiration
Lecture 2
May, 2009
ƒCO2--generated H+ in the brain is normally the primary
regulator of ventilation:
After quiet
breathing
After
hyperventilating
After breathing
into a p
plastic bag
g
CO2 level
Breath-Holding,
Seconds
Normal
80
Low
128
High
28
ƒDecreased arterial PO2 increase ventilation only as an
emergency mechanism.
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
TABLE 1. Influence of Chemical Factors on Respiration
Chemical Factor Effect on the Peripheral
Chemoreceptors
Effect on the Central
Chemoreceptors
PO2 in the
Arterial Blood
Stimulates only when the
arterial PO2has fallen to the
point
i t of
fb
being
i lif
lifethreatening(<60mmHg);
an emergency mechanism
Directly depresses the
central chemoreceptros and
th respiratory
the
s i t
center
t its
itself
lf
when <60mmHg
PCO2 in the
Arterial Blood
( H+ in the
Brain ECF)
Weakly stimulates
Strongly stimulates; is the
dominant control of
ventilation
(Levels >70-80mmHg directly
depress
p
the respiratory
p
y
center and central
chemoreceptors)
H+ in the
Arterial Blood
Stimulates; important in acidbase balance
Does not affect; cannot
penetrate the blood-brain
barrier
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
6
Human and Animal Physiology; Respiration
Lecture 2
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
2009/5/8
Copyright:Yingyu Sun-CLOS,BNU
May, 2009
©2009, Yingyu Sun
7
Human and Animal Physiology; Respiration
Lecture 2
2009/5/8
May, 2009
Copyright:Yingyu Sun-CLOS,BNU
©2009, Yingyu Sun
8