Respiratory System
14
The goal of these lectures is to discuss
basic respiratory physiology. This lecture
will discuss gas transport, control, hypoxia
and non-respiratory functions of lungs. The sections for this lecture are:
Transport of gases PO2, PCO2, H+ conc, t°C, DPG, Hb saturation
Bhor, Haldane, respiratory acidosis / alkalosis
Neural control of ventilation
Rhythmical breathing, PO2, PCO2, and H+ conc
Exercise, other ventilatory responses
Life is a series of chemical reactions occurring in
compartmentalized environments.
The main purpose of life is to keep itself alive
Physiology, the study of how life works, is based
on the simultaneous occurrence of the following
Hypoxia and non-respiratory functions of lungs) three concepts:
Hypoxia and acclimatization to high altitude
levels of organization
Non-respiratory functions of the lungs
structure / function relationship
homeostatic regulation
PCO2
PO2
pH
Pa
neural CV center
inputs
cardio +
cardio -
output
vasoconstriction
chemo & baroreceptors
extrinsic
heart
periphery
(local control)
baroreceptor mechanism
(e.g. carotid sinus)
intrinsic
lung
(local control)
where we would like to be at the end
of the cardiovascular and respiratory
sections, by the end of this week
1
Respiratory System
Introduction, last lecture
Transport of O2, CO2 and H ions in blood, this lecture
Structure / function, gas laws, lungs / chest
wall relations, pressures / forces
Lung mechanics, last lecture
Ventilation, inspiration / expiration,
complience / resitance
Lung volume /capacities, alveolar ventilation /
dead space
Partial pressures of gases and their diffusion
in liquids
Alveolar gas pressures and alveolar - blood
exchange
Matching alveolar ventilation and alveolar
blood flow
Gas exchange in tissues
Hemoglobin (Hb), effect of PO2 on Hb saturation
Blood PCO2, H+ conc, t°C, DPG on Hb saturation
Carbamino compounds and carbonic anhydrase
Total blood carbon dioxide and the Haldane effect
Respiratory acidosis and respiratory alkalosis
Control of respiration, this lecture
Neural generation of rhythmical breathing
Control of ventilation by PO2, PCO2, and H+ conc
Control of ventilation during exercise
Other ventilatory responses
Hypoxia and non-respiratory functions of lungs, this lecture
Hypoxia and acclimatization to high altitude
Non-respiratory functions of the lungs
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
2
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Oxygen Content at Systemic
Arterial Blood at Sea Level
Respiratory acidosis and
respiratory alkalosis
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Gas exchange
as function of
capillary length
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
3
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
4
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
(increased affinity)
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Bohr
effect
Carbamino compounds and
carbonic anhydrase
(decreased affinity)
base
pH = pK + log acid
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
pH = pK + log
HCO3
H2CO3
pH = pK + log
HCO3
PCO2
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
In the
lungs
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
base
pH = pK + log acid
pH = pK + log
HCO3
H2CO3
pH = pK + log
HCO3
PCO2
5
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
pH = pK + log
HCO3
H2CO3
pH = pK + log
HCO3
PCO2
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
(increased
affinity)
(decreased
affinity)
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
(increased affinity)
(increased
affinity)
(decreased
affinity)
(decreased
affinity)
Total blood carbon dioxide
and the Haldane effect
base
pH = pK + log acid
Respiratory acidosis and
respiratory alkalosis
pH = pK + log
HCO3
H2CO3
pH = pK + log
HCO3
PCO2
6
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Effects of Various Factors on
Hemoglobin
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
In the
tissue
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
base
pH = pK + log acid
pH = pK + log
HCO3
H2CO3
pH = pK + log
HCO3
PCO2
7
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
H ion
binding
by Hb
Transport of gases
Hemoglobin (Hb), effect of
PO2 on Hb saturation
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
Carbamino compounds and
carbonic anhydrase
mechanism
for B & C
???
Total blood carbon dioxide
and the Haldane effect
Respiratory acidosis and
respiratory alkalosis
8
Transport of gases
1, respiratory acidosis
2, respiratory alkalosis
3, metabolic acidosis
4, metabolic alkalosis
Hemoglobin (Hb), effect of
PO2 on Hb saturation
60
mmHg
PCO2
40
mmHg
Blood PCO2, H+ conc, t°C,
DPG on Hb saturation
20
mmHg
Carbamino compounds and
carbonic anhydrase
Total blood carbon dioxide
and the Haldane effect
HCO3
24
2
3
Respiratory acidosis and
respiratory alkalosis
pH = pK + log
4
1
HCO3
PCO2
7.2
7.4
7.6
pH
Control of respiration
• Neural
generation of
rhythmical
breathing
PONS
stimulatory
pneumotaxic
inhibitory
control of respiration
means control of
amplitude and
frequency
apneustic
• Control of
ventilation by
PO2, PCO2,
and H+ conc
• Control of
ventilation
during
exercise
MEDULLA
Inspiratory
center is
tonically
active
I
other inputs
lung
stretch
receptors
inspiratory
muscles
E
Expiratory
center is active
only when
stimulated
SPINAL CORD
expiratory
muscles
9
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
Control of respiration
• Neural
generation of
rhythmical
breathing
Major Stimuli for the Central and the
Peripheral Chemoreceptors
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
10
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
Control of respiration
• Neural
generation of
rhythmical
breathing
2
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
11
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
stimulate inspiratory center
periphereal mechanoreceptors (skin, joints, etc..)
inhibit inspiratory center
upper respiratory tract (swallowing, diving reflex)
increase baroreceptor activity
decreases inspiration & venous return
decrease baroreceptor activity
increases inspiration & venous return
increase PCO2 --> increases Va
decrease PCO2 --> decrease Va
increase H --> increase Va
decrease H --> decrease Va
increase Po2 --> decrease Va
decrease PO2 --> increase Va
12
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
Control of respiration
• Neural
generation of
rhythmical
breathing
• Control of
ventilation by
PO2, PCO2, and
H+ conc
• Control of
ventilation
during exercise
13
Hypoxia
• Hypoxia and
acclimatization
to high altitude
Causes of a Decreased Arterial PO2
(Hypoxic Hypoxia) in Disease
Hypoxia
• Hypoxia and
acclimatization
to high altitude
Acclimatization to the Hypoxia of
High Altitude
14
Other lung functions
NON-RESPIRATORY FUNCTIONS
OF THE LUNGS
(in addition to gas exchange and
+
regulation of H concentration)
“sieve” for small blood clots
endothelial cells lining lung capillaries
(eg. histamine, ACE, exogenous GnRH & cocaine ??)
Respiratory System
S
E
15
Respiratory System
comparator /
integrator
what it actually is (info from
feedback), is compared with what it
should be (info from set-point) in a …
Homeostasis, or constancy
of the internal environment,
is needed for chemical
reactions underlying life
to occur. It is maintained,
predominantly, through
negative feedback
mechanisms
S
E
effect
error signal
amplification
effectors mechanism
integrators compare what it should be with what it actually is and generate an error signal
Respiratory System
Respiratory / cardiovascular
interaction
PO2
DR=PD x A x DC / D
(DC, CO2 = 20 DC, O2)
ventilatory
pump
chemoreceptors
O2
supply
V=RF x TV
CO=HR x SV
S
E
receptor
control of
amplitud &
frequency
venous
return
CNS
baroreceptors
VA / Q
circulatory
pump
Hemoglobin
O2
content
BP
blood
flow
integrators compare what it should be with what it actually is and generate an error signal
16
Respiratory System
NEURAL
RESPIRATORY
CENTER
AP
inspiratory
expiratory
AP
O2
O2
THORACIC
COMPONENTS
CO2
O2
CO2
PCO2
DISTRIBUTION
CENTER
pH
PO2
CO2
Pa
O2
S
inputs
CO2
METABOLIC
COMPONENTS
(all cells)
blood
related
E
receptor
AP
neurogenics
integrators compare what it should be with what it actually is and generate an error signal
PCO2
PO2
pH
Pa
neural CV center
inputs
cardio +
cardio -
output
vasoconstriction
chemo & baroreceptors
extrinsic
heart
periphery
(local control)
baroreceptor mechanism
(e.g. carotid sinus)
intrinsic
lung
(local control)
where we would like to be at the end
of the cardiovascular and respiratory
sections, by the end of this week
17
Respiratory System
14
The goal of these lectures was to discuss
basic respiratory physiology. This lecture
discussed gas transport, control, hypoxia
and non-respiratory functions of the lungs. The sections for this lecture were:
Transport of gases PO2, PCO2, H+ conc, t°C, DPG, Hb saturation
Bhor, Haldane, respiratory acidosis / alkalosis
Neural control of ventilation
Rhythmical breathing, PO2, PCO2, and H+ conc
Exercise, other ventilatory responses
16 kidney 1 follows
Life is a series of chemical reactions occurring in
compartmentalized environments.
The main purpose of life is to keep itself alive
Physiology, the study of how life works, is based
on the simultaneous occurrence of the following
Hypoxia and non-respiratory functions of lungs) three concepts:
Hypoxia and acclimatization to high altitude
levels of organization
Non-respiratory functions of the lungs
structure / function relationship
homeostatic regulation
AT THE MIDDLE OF THE ROAD
I wonder how
will I look after
the next section
Kidney hat
Resp hat
CV hat
???
metabolism hat
repro hat
GI hat
I’D RATHER BE AT THE BEACH
18