P PP P P
PP
Exam
I
Chapters 23: Respiratory System
(Figures 23.1 - 23.7)
1) External nares
O.S.U.
2) Nasal cavity (PCCE)
2
3
• moisten/warms air
Exam
II
4
• filters air
1
Reminder:
Exam I → Tomorrow
Today:
A. Respiratory system anatomy
B. Mechanisms of breathing
C. Gas Exchange
3)
4)
5)
6)
7)
8)
Uvula
Nasopharynx (PCCE)
Oral Cavity (StSE)
Oropharynx (StSE)
Laryngopharynx (StSE)
Larynx (HC)
6
5
• resonance chamber
7
8
9
12
12
10
11
13
14
• provide open airway
Mariners
Twins
2
5
Chapters 23: Respiratory System
• channel air/food (epiglottis)
• voice production (vocal cords)
Chapters 23: Respiratory System
(Figures 23.1 - 23.7)
9) Trachea (PCCE) with rings (HC)
10) Right lung (3 lobes)
11) Left lung (2 lobes)
1
12) Primary Bronchi (right & left) (PCCE)
13) Secondary bronchi (PCCE)
14) Tertiary bronchi (PCCE)
15) Diaphragm
10
O.S.U.
2
3
4
6
5
7
8
9
12
12
11
13
14
15
Chapters 23: Respiratory System
Functional Anatomy:
The Bronchial Tree:
Order of bronchi / bronchiole
low
high
Cartilage:
rings
plates / gone
Epithelium:
columnar
cilia
Smooth muscle increases
cuboidal
no cilia
15
Functional Anatomy:
The Bronchial Tree:
The trachea bifurcates (divides in two) to form:
• Primary (1º) bronchi
• Secondary (2º) bronchi
• Tertiary (3º) bronchi
Ø Bifurcation continues up to 23 orders
Naming of pathways:
• > 1 mm diameter = bronchi
• < 1 mm diameter = bronchioles
• < 0.5 mm diameter = terminal bronchioles
Chapters 23: Respiratory System
O.S.U.
16
17
18
19
2
3
4
1
6
5
7
8
9
12
12
10
11
13
14
15
Chapters 23: Respiratory System
Functional Anatomy:
16) Wall of thoracic cavity
17) Parietal pleura
18) Pleural cavity (pleural fluid)
19) Visceral pleura
Chapters 23: Respiratory System
Conducting Zone
O.S.U.
16
17
18
19
2
3
16
4
17
18
1
6
5
19
7
8
9
12
23
12
10
11
20
24
22
21
13
26
14
25
27
Respiratory Zone
15
Chapters 23: Respiratory System
Functional Anatomy:
20) Terminal bronchiole (SCE)
21) Respiratory bronchiole (SCE)
22) Air sac (SSE)
23) Alveolus (SSE)
23
20
• Alveolar pores
• Alveolar macrophages
24
22
21
24) Pulmonary capillary
25) Pulmonary venule (high O2)
26) Pulmonary arteriole (low O2)
26
25
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Functional Anatomy:
23
20
24
23
20
24
22
21
22
21
26
25
26
25
27
Diffusion is the force that drives gas exchange in the lungs:
O2 and CO2 move from [high] to [low]
Chapters 23: Respiratory System
Respiratory System:
A. Functional Anatomy
B. Mechanisms of Breathing
C. Gas Exchange
D. Gas Transport
E. Control of Respiration
Supplies the body
with oxygen and
disposes of carbon
dioxide
27) Red blood cell
28) Capillary endothelium
29) Fused basement membranes
• Capillary & alveolus
30) Epithelium of alveolus
28
29
30
Chapters 23: Respiratory System
Mechanisms of Breathing:
Pressure relationships in the thoracic cavity:
• Respiratory pressures relative to atmospheric pressure
• Atmospheric pressure = ~760 mm Hg
• Consider Patmospheric = 0 mm Hg
1) Intrapulmonary Pressure (w/in the alveoli):
• Static conditions = 0 mm Hg
• Inhalation (inspiration) = Pip slightly negative
• Exhalation (expiration) = Pip slightly positive
2) Intrapleural pressure (w/in pleural cavity):
• Always relatively negative (~ -4 mm Hg)
• Prevents lungs from collapsing
Chapters 23: Respiratory System
Mechanisms of Breathing:
Chapters 23: Respiratory System
intrapleural pressure
(Pip = -4 mm Hg)
chest wall
Mechanisms of Breathing:
Why is the intrapleural pressure negative?
Interaction of opposing forces
lung surface
intrapulmonary
pressure
(Pin = 0 mm Hg)
pleural cavity
Forces acting to collapse lung:
1) Elasticity of lungs
2) Alveolar surface tension
Force resisting lung collapse:
1) Rigid chest wall
Surface tension of serous fluids
keep lungs “stuck” to chest wall
Forces equilibrate at Pip = -4 mm Hg
atmospheric pressure = Pout = 0 mm Hg
Respiratory Pressures in Static Conditions
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Pulmonary Ventilation: Inspiration & expiration
• A mechanical process
• Dependant on volume changes in thoracic cavity
Pneumothroax:
“sucking chest wound”
Boyle’s Law
P1V1 = P2V2
Puncture of the chest wall
resulting in the inability to
generate negative pressure
and expand the lungs.
Example:
P = pressure of gas (mm Hg)
V = volume of gas (mm3)
P1 = initial pressure, V1 = initial volume
P2 = resulting pressure, V2 = resulting volume
4 mm Hg (2 mm3) = P2 (4 mm3)
P2 = 2 mm Hg
CHANGING THE VOLUME RESULTS IN
INVERSE CHANGE OF PRESSURE!
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Inspiration: Muscular expansion of thoracic cavity
Inspiration: Muscular expansion of thoracic cavity
1) Contraction of diaphragm
• Lengthens thorax (pushes liver down)
0 mm Hg
0 mm Hg
-4 mm Hg
-? mm Hg
0 mm Hg
? mm Hg
Diaphragm
Diaphragm
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Inspiration: Muscular expansion of thoracic cavity
Inspiration: Muscular expansion of thoracic cavity
1) Contraction of diaphragm
• Lengthens thorax (pushes liver down)
1) Contraction of diaphragm
• Lengthens thorax (pushes liver down)
0 mm Hg
0 mm Hg
-? mm Hg
2) Contraction of external intercostal
muscles
-8 mm Hg
2) Contraction of external intercostal
muscles
• Expands thorax
• Expands thorax
Results in:
0 mm Hg
?
• Reduced intrapleural pressure
Diaphragm
0
? mm Hg
Diaphragm
Chapters 23: Respiratory System
Inspiration:
Mechanisms of Breathing:
Inspiration: Muscular expansion of thoracic cavity
1) Contraction of diaphragm
• Lengthens thorax (pushes liver down)
0 mm Hg
-8 mm Hg
2) Contraction of external intercostal
muscles
• Expands thorax
Results in:
• Reduced intrapleural pressure
0 mm
-1
mmHg
Hg
• Reduced intrapulmonary pressure
• Air enters lung
Diaphragm
(Figure 23.13)
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Expiration: Retraction of thoracic cavity
Expiration: Retraction of thoracic cavity
1) Passive Expiration
• Diaphragm relaxes
0 mm Hg
0 mm Hg
-8 mm Hg
-1 mm Hg
Diaphragm
-? mm Hg
?
0 mm Hg
Diaphragm
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Expiration: Retraction of thoracic cavity
1) Passive Expiration
• Diaphragm relaxes
• External intercostals relax
Expiration: Retraction of thoracic cavity
0 mm Hg
-? mm Hg
1) Passive Expiration
• Diaphragm relaxes
• External intercostals relax
• Lungs rebound (elasticity of lungs)
0 mm Hg
?
Diaphragm
Diaphragm
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Expiration: Retraction of thoracic cavity
Results in increased pressure
in thoracic cavity and air exits
Expiration: Retraction of thoracic cavity
0 mm Hg
-4 mm Hg
1) Passive Expiration
• Diaphragm relaxes
• External intercostals relax
• Lungs rebound (elasticity of lungs)
1
0 mm Hg
2) Active (“Forced”) Expiration
• Abdominal muscles contract
Diaphragm
Chapters 23: Respiratory System
Expiration:
Expiration: Retraction of thoracic cavity
2) Active Expiration
• Abdominal muscles contract
• Forces air out of lungs
0 mm Hg
-4 mm Hg
0 mm Hg
1 mm Hg
Diaphragm
Mechanisms of Breathing:
1) Passive Expiration
• Diaphragm relaxes
• External intercostals relax
• Lungs rebound (elasticity of lungs)
-? mm Hg
0 mm Hg
?
Mechanisms of Breathing:
1) Passive Expiration
• Diaphragm relaxes
• External intercostals relax
• Lungs rebound (elasticity of lungs)
0 mm Hg
0 mm Hg
-4 mm Hg
0 mm Hg
> 1 mm Hg
Diaphragm
(Figure 23.13)
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Physical Factors Influencing Pulmonary Ventilation:
Physical Factors Influencing Pulmonary Ventilation:
1) Airway resistance
• Flow of air = change in pressure / resistance (F = ∆P / R)
• R = 1 / radius4
Ø Asthma - allergic response to irritants
3) Lung Compliance
• constriction of bronchioles = ↓ radius = ↑ resistance
2) Surface tension in alveoli
• Moist alveolar surfaces attract to one another (H2O polarity)
• Collapses alveoli
• Alveolar cells (type II) secrete surfactant (e.g. detergents)
Ø IRDS = Infant respiratory distress syndrome
• “Stretchiness” of lung (↑ compliance = easier to expand lung)
• Determined by:
a) Elasticity of lung
b) Surface tension
• Compliance diminished by factors which:
1) Reduce resilience of lung
2) Block smaller passages
3) Reduce surfactant production
4) Decrease flexibility of thoracic cage
Ø Emphysema: Lungs lose elasticity (too compliant)
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Respiratory Volumes:
Respiratory Capacities:
1) Tidal Volume (normal breathing)
1) Inspiratory Capacity
3) Expiratory Reserve Volume
• Forced expiration
Volume (ml)
• Forced inspiration
• Total amount of inspired air after
tidal expiration
500 ml
4) Residual Volume
2100 - 3200 ml
Volume (ml)
2100 - 3200 ml
2) Inspiratory Reserve Volume
500 ml
1000 - 1200 ml
1000 - 1200 ml
1200 ml
1200 ml
• Keeps alveoli open
• Prevents lung collapse
Spirometric reading
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Respiratory Capacities:
Respiratory Capacities:
1) Inspiratory Capacity
1) Inspiratory Capacity
• Total amount of inspired air after
tidal expiration
• Amount of air in lungs following
tidal expiration
Volume (ml)
2) Functional Residual Capacity
2100 - 3200 ml
• Total amount of inspired air after
tidal expiration
2) Functional Residual Capacity
500 ml
1000 - 1200 ml
• Amount of air in lungs following
tidal expiration
3) Vital Capacity
2100 - 3200 ml
Volume (ml)
Mechanisms of Breathing:
500 ml
1000 - 1200 ml
• Total amount of exchangeable air
1200 ml
1200 ml
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Mechanisms of Breathing:
Mechanisms of Breathing:
Respiratory Capacities:
Nonrespiratory Air Movements:
1) Inspiratory Capacity
• Total amount of inspired air after
tidal expiration
• Amount of air in lungs following
tidal expiration
Volume (ml)
2) Functional Residual Capacity
2100 - 3200 ml
500 ml
1000 - 1200 ml
3) Vital Capacity
• Total amount of exchangeable air
4) Total Lung Capacity
1200 ml
• Sum of all lung volumes
1) Cough
• Remove foreign substances / mucus (lower respiratory)
2) Sneeze
• Clear upper respiratory tract (nasal cavity)
3) Crying/Laughing
• Emotionally induced mechanism
4) Hiccup
• Irritation of diaphragm / phrenic nerve
5) Yawn
• Ventilates all alveoli (why?)
Chapters 23: Respiratory System
Respiratory System:
Chapters 23: Respiratory System
Gas Exchange:
Physical Properties of Gases:
A. Functional Anatomy
B. Mechanisms of Breathing
1) Dalton’s Law of Partial Pressures:
• The total pressure of a gas is equal to the sum of the
pressures of its constituents
C. Gas Exchange
D. Gas Transport
E. Control of Respiration
0.04%
Carbon
Dioxide
PAtmosphere = 760 mm Hg
20.94%
Oxygen
PO2 = 0.21 x 760 mm Hg = 159 mm Hg
Supplies the body
with oxygen and
disposes of carbon
dioxide
PN2 = 0.79 x 760 mm Hg = 601 mm Hg
79%
Nitrogen
PCO2 = 0.0004 x 760 mm Hg = 0.30 mm Hg
% Composition of Air
Chapters 23: Respiratory System
Gas Exchange:
Physical Properties of Gases:
0.21 mm Hg
Carbon
Dioxide
Chapters 23: Respiratory System
Gas Exchange:
Physical Properties of Gases:
159 mm Hg
Oxygen
Partial Pressure
of Dry Room Air
601 mm Hg
Nitrogen
2) Henry’s Law:
• Gases in a mixture dissolve in a liquid in proportion to their
partial pressures
• Gases diffuse down pressure gradients
Additional factors affecting gas/liquid interchange:
• Solubility of gas in water
• Carbon Dioxide >> Oxygen >> Nitrogen
Ø “The Bends” (pg 872)
• Temperature
• Solubility inversely related to temperature
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Gas Exchange:
Why is alveolar gas high in CO2 and water vapor?
Lung air modified by gas exchange:
1) O2 into blood; CO2 out of blood
2) Humidification of air (conducting pathways)
3) Mixture of fresh and residual air / breath
0.04%
Carbon
Dioxide
20.94%
Oxygen
H2O = 6.2%
Gas Exchange:
External / Internal Respiration:
1) External Respiration (O2 / CO2 exchange between blood and lungs)
• Pulmonary gas exchange driven by gas partial pressures
• PO2 in alveoli = ~100 mmHg
Net movement into blood
• PO2 in blood = ~40 mmHg
• PCO2 in alveoli = ~40 mmHg
Net movement into alveoli
• PCO2 in blood = ~45 mmHg
O2 = 13%
N2 = 74.5%
79%
Nitrogen
CO2 = 6%
% Composition of Air
% Composition of Lung Air
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Gas Exchange:
External / Internal Respiration:
1) External Respiration (O2 / CO2 exchange between blood and lungs)
• Pulmonary gas exchange driven by gas partial pressures
• PO2 in alveoli = ~100 mmHg
Net movement into blood
• PO2 in blood = ~40 mmHg
• PCO2 in alveoli = ~40 mmHg
Net movement into alveoli
• PCO2 in blood = ~45 mmHg
Gas Exchange:
Ventilation-perfusion Coupling:
• Mechanism for matching flow of blood with volume of gas
in alveoli (Autoregulatory homeostasis)
1) Ventilation = amount of gas reaching alveoli
2) Perfusion = blood flow in pulmonary capillaries
Bronchioles
Alveoli
• Thin, extensive exchange area maximizes exchange rates
• Thickness < 1.0 µm; exchange area ~ 50-70 m2
• Ventilation-perfusion Coupling
Pulmonary venules
Pulmonary arterioles
Pulmonary
capillaries
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Gas Exchange:
Ventilation-perfusion Coupling:
Gas Exchange:
Ventilation-perfusion Coupling:
When PO2 is low and PCO2 is high in alveoli:
When PO2 is low and PCO2 is high in alveoli:
1) Bronchioles dilate (↑ ventilation)
Bronchioles
Bronchioles
Alveoli
↓ PO2
↑ PCO2
Pulmonary venules
Pulmonary arterioles
Pulmonary
capillaries
Alveoli
↓ PO2
↑ PCO2
Pulmonary venules
Pulmonary arterioles
Pulmonary
capillaries
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Gas Exchange:
Ventilation-perfusion Coupling:
Gas Exchange:
Ventilation-perfusion Coupling:
When PO2 is low and PCO2 is high in alveoli:
When PO2 is high and PCO2 is low in alveoli:
1) Bronchioles dilate (↑ ventilation)
2) Pulmonary arterioles constrict (↓ blood flow)
Bronchioles
Bronchioles
Alveoli
↓ PO2
↑ PCO2
Alveoli
↑ PO2
↓ PCO2
Pulmonary venules
Pulmonary arterioles
Pulmonary venules
Pulmonary arterioles
Pulmonary
capillaries
Pulmonary
capillaries
Chapters 23: Respiratory System
Chapters 23: Respiratory System
Gas Exchange:
Ventilation-perfusion Coupling:
Gas Exchange:
Ventilation-perfusion Coupling:
When PO2 is high and PCO2 is low in alveoli:
When PO2 is high and PCO2 is low in alveoli:
1) Bronchioles constrict (↓ ventilation)
1) Bronchioles constrict (↓ ventilation)
2) Pulmonary arterioles dilate (↑ blood flow)
Bronchioles
Bronchioles
Alveoli
↑ PO2
↓ PCO2
Alveoli
↑ PO2
↓ PCO2
Pulmonary venules
Pulmonary arterioles
Pulmonary venules
Pulmonary arterioles
Pulmonary
capillaries
Pulmonary
capillaries
Chapters 23: Respiratory System
Gas Exchange:
External / Internal Respiration:
Gas movements
in body:
2) Internal Respiration (O2 / CO2 exchange between blood and tissues)
• Driven by gas partial pressures
• PO2 in blood = ~104 mmHg
• PO2 in tissue = ~40 mmHg
Net movement into tissue
• PCO2 in blood = ~40 mmHg
• PCO2 in tissue = ~45 mmHg
Net movement into blood
(Figure 23.17)