Alveolar Membrane Gradients
Air Blood
Oxygen
Carbon
Dioxide
Clustered Alveoli
1
2
Airway 3
Generations 4
5
6
17
Respiratory
Bronchioles
18
The
19
Primary Alveolar
20 Ducts
Lobule
21
23
22
Alveolar Sac
Airway Cross-sectional Area
variation with distance from mouth
trachea
alveolar
mouth
membrane
at RV (min lung volume)
at TLC (max lung volume)
Contrasting Emboli Effects
embolus
embolus
Pulmonary capillaries: Systemic capillaries:
others cover for blocked serve a particular area
one emboli filtered safely so area killed
Face View of 1/6th of Alveolar Septum
The
Alveolar
60 um
Wall
Red cell Transverse Capillary endothelium
Basement membrane
Section Alveolar epithelium
10
um Enlargement Alveolar
fluid
lining
1 um
Lung Volumes
6.0
Litres VC
IRV
IC
3.5
VT TLC
3.0
ERV
FRC
1.5
0
RV
Volumes and Flows
VT = 500 ml/breath Ventilation = 7.5 L/min
VD = 150 ml/breath = VT X f (breaths/min)
the dead space volume
Alveolar Ventilation
= 5.25 L/min
FRC = 3000 ml
Cardiac output
Gas exchange volume = 5 L/min
Capillary volume = 70 ml
The
Diaphragm
Muscle
The
SPINE
Intercostal
Muscles
Lung Inflation
PB =0 PB =0
P= 0
P
P
The
Intrapleural
Space
Intrapleural
Space
Pneumothorax
PB =0 PB =0
P=0
P=0
P=-5 P=0
NORMAL PNEUMOTHORAX
Lung
Intrapleural
Lung Pressure Compliance
Volume
elastic limit Lung
Volume
Slope = CL
negative Intrapleural Pressure positive
Surface
Tension
P
Types of Flow
Laminar Turbulent Intermediate
Pressure Gradient Types of Flow
Laminar Flow Turbulent Flow
- R constant - R varies with flow
-silent - noisy
-viscosity dependent - density dependent
Airway Flow
Ventilation-Perfusion Matching
. . .
V=0 V=1 V=1
Obstruction
. . .
Q=1 Q=1 Q=0 Embolus
Venous Normal Wasted
Admixture Ventilation
Pco2 mmHg Po2 mmHg
100
40
50
40
60
80
mixed venous blood
46
37
pulmonary artery
PAco2 = 39
alveolar gas
PAo2 = 106
alveolar gas
pulmonary capillary blood
arterialized blood in
pulmonary capillary
Pulmonary Gas Transfer
venous admixture in
pulmonary veins
arterial blood
39
97
Pao2
Paco2
Oxygen Dissociation Curve
100 20
arterial
Oxygen Concentration ml/100ml
Oxygen Saturation %
70 14
venous
Pco2 40
Pco2 46
30 40 venous arterial 100
Oxygen Partial Pressure mmHg
Carbon Dioxide Dissociation Curve
Carbamino CO2 at Po2 40 (venous blood)
60 at Po2 100 (arterial blood)
Concentration ml/100ml
52 venous
46 arterial
Carbon Dioxide
40
CO2 as
20 Bicarbonate
0 Dissolved
0 20 40 46 60 80 CO2
arterial venous
Carbon Dioxide Partial Pressure mmHg
Carbonic Acid Formation
-
CO2 H2O H2CO3 H+ HCO3
H.Hb
-
Cl
Carbonic Hemoglobin Bicarbonate leaves the red
anhydrase buffers hydrogen cell and chloride enters in
enzyme catalyzes ions (in red cell) exchange “chloride shift”
(in red cell)
Linear Henderson-Hasselbach
Normally:
24 Pco2
[H+] = [H+] = 40 nmol/L
[HCO3]
Pco2 = 40 mmHg
[HCO3] = 24 mmol/L
Regulation of Breathing
Pulmonary Metabolic Carbon
Ventilation Dioxide Production
Carbon Dioxide Pco2
stores
Po2
Oxygen
stores
Metabolic Pulmonary Ventilation
Oxygen
Consumption
Respiratory Negative Feedback Regulator
Gas Exchange
Ventilation Other Po2 Pco2
Chemo- Acid-Base
[H+]
reflexes
[PO4-] SID
[Alb]
The Metabolic Hyperbola
30
25
Ventilation L/min
20
15
10
5
0
0 10 20 30 40 50 60 70 80
Arterial Pco2 mmHg
The Central Chemoreflex
50
40
Ventilation L/min
30
20
10
0
35 40 45 50 55
Arterial Pco2 mmHg
The Peripheral Chemoreflex
50
40
Ventilation L/min
30 Arterial Po2
40
mmHg
20
60
10
100
0
35 40 45 50 55
Arterial Pco2 mmHg
The Chemoreflex Control of Breathing
50
normal resting 40 60 100 >150
40
Ventilation L/min
equilibrium point Arterial Po2
mmHg
30
wakefulness
drive
20
10
resting metabolic hyperbola
0
35 40 45 50 55
Arterial Pco2 mmHg
Neural Factors
Voluntary Control Emotions
(motor cortex) (forebrain)
Posture
(cerebellum)
Cough Limbic
Sneeze etc. Rhythm System
(medulla) Generator
(medulla)
Reticular
Formation
Respiratory Motoneurons Sensory
(spinal cord) Stimuli
(pain, startle)
Neuron Firing Patterns
I
INC
E
INC
I
DEC
E
DEC
I
CON
inspiration expiration inspiration expiration
Medullary Respiratory Groups
DRG
VRG
Cross-sectional view at
obex obex
anatomical
landmark
Dorsal view
Feedback Hierarchy
EFFERENT AFFERENT
Medullary Central
Respiratory Chemoreceptors
Neurons (medulla)
X
Spinal IX Peripheral
Respiratory X Chemoreceptors
Upper (carotid bodies)
Motoneurons
Airway Muscle
Muscles Receptors
Respiratory
Muscles
Airway and
Airway Po2 and [H+]
Lung Receptors
Smooth
Muscle Pulmonary
Ventilation
The Time Course of Changes During
Moderate Exercise
Changes (e.g. Ventilation)
0 5 time (min.)
rest exercise rest
Changes with increasing Work Rate
Aerobic Anaerobic
Respiratory Variables
Pco2
Po2 , [H+] & lactate
Exercise Work Rate
Astrand Fitness Test Assumption 2
Heart Rate
Work Rate or Oxygen Cost
Astrand Fitness Test Assumption 3
max
Heart Rate
max
Work Rate or Oxygen Cost
Astrand Fitness Test Assumption 4
max
Heart Rate
max
Work Rate or Oxygen Cost
The Fitness Message
max
Heart Rate
A’s max B’s max C’s max
Work Rate or Oxygen Cost
Lance Armstrong
7-time Winner of the Tour de
France
Resting Heart Rate
32 beats per minute