6. with oxygen and
disposes of carbon
dioxide
Fig. 23-12, p. 831
Systemic & Pulmonary Circulation
Fig. 20.1, Seeley, 7th ed.
Respiration Includes:
Pulmonary ventilation
Pumping air in/out of lungs
External respiration
Gas exchange at blood-gas barrier in lung
Transport of respiratory gases by blood
Internal respiration
Gas exchange at tissues
Respiratory anatomy is also involved in speech production &
smell
Thibodeau, 6th ed., fig. 24-1
Overall Anatomy: Location & Position of Lungs & Bronchial
tree
Fig. 23.10, Thibodeau, 6th ed.
Fig. 22.1, Saladin, 4th ed.
7. 5
Pleurae and Pleural Fluid
Visceral & parietal layers
Pleural cavity & fluid
Functions
Lubrication for reduction of friction
Compartmentalization
Creates pressure gradient
Fig 1.10, Marieb, 6th, ed
Fig. A.8, Saladin, 3rd ed.
Functional Anatomy
2 Zones:
Conducting Zone - cleanse, humidify & warm incoming air
Respiratory Zone - gas exchange
Figure 23–1, 814
8. Fig. 23-2, p. 816
Fig. 22.8, Saladin, 4th ed.
Respiratory Epithelium
Pseudostratified ciliated columnar epithelium (PCCE)
8
Nasal Cavity & Nose
Airway provider
Warms & moistens incoming air (PCCE)
Filter/clean (PCCE)
Superior concha & meatus
External Nares (nostril)
Middle concha & meatus
Inferior concha & meatus
Internal Nares
Uvula
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
9. Figure 23–3, 818
Superior concha & meatus
Middle concha & meatus
Inferior concha & meatus
Nasal Cavity & Nose
Resonating chamber for speech
Olfaction
External Nares (nostril)
Superior concha & meatus
Middle concha & meatus
Inferior concha & meatus
Internal Nares
Uvula
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
Figure 14–19, 481
Nasopharynx
Air passage only
10. Closed off by uvula
PCCE
Pharyngeal tonsil (adenoids)
Auditory tubes
Pharyngeal tonsil
Nasopharynx
Auditory tube
Uvula
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
Fig. 22.3, Saladin, 4th ed.
Figure 17-20, 573
Oropharynx
Food & air
Stratified squamous epithelium (StSE)
Lingual & palatine tonsils
Oropharynx
Lingual tonsil
Palatine tonsil
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
Fig. 22.3, Saladin, 4th ed.
11. Figure 4–3b, 112
Laryngopharynx & Oral Cavity
Food & air
StSE
Laryngopharynx
Oral Cavity
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
Fig. 22.3, Saladin, 4th ed.
Larynx – Voice Box
Air passage only
PCCE
Functions
Provide open airway
Air passage only
Voice
Glottis
Superior opening
Epiglottis
Flap of tissue that guards glottis – directs food & drink to
esophagus
Epiglottis
12. Glottis
Vocal cord
Trachea
Esophagus
Fig. 22.3, Marieb, 6th ed. (reversed), similar to 23.3, 818
Details of Laryngeal Anatomy
Fig. 23-4, p. 820
Action of Vocal Cords
Fig. 23.4, Seeley, 7th ed
Trachea, Primary Bronchi & Lungs
Trachea
Hyaline cartilage rings
PCCE
Primary Bronchi
L & R
PCCE
Lungs
Left – 2 lobes
Right – 3 lobes
Fig. 22.7, Marieb, 6th ed.
13. Cross-section through trachea
Fig. 22.7, Saladin, 4th ed.
Esophagus
The Bronchial Tree
Trachea bifurcates (divides in 2) to form:
Primary bronchi
Secondary bronchi
Tertiary bronchi
Naming of pathways
> 1 mm diameter = bronchi
< 1 mm diameter = bronchioles
< 0.5 mm diameter = terminal bronchioles
Fig. 22.7, Marieb, 6th ed.
Fig. 23.6, Seeley, 7th ed
Structural Changes in Bronchial Tree
Support – cartilaginous rings become plates, and then are absent
Epithelium – PCCE becomes simple columnar epithelium then
simple cuboidal epithelium with fewer cilia & no mucous cells
at bronchioles
Smooth Muscle increases - controls bronchioles
14. Trachea
Bronchioles
Cartilage
Mucous
Smooth muscle
20
Respiratory zone begins w/ respiratory bronchioles
**Alveoli are the site of gas exchange!!!
Fig. 22.9, Marieb, 6th ed.
Bronchodilation
Sympathetic
Bronchoconstriction
Parasympathetic
Allergic rxns
Asthma
Fig. 23-9, p. 825
Bronchi & lobules of lung
Fig. 23-9b, part 2, p. 825
15. Fig. 23-9, p. 825
Bronchi & lobules of lung
23
Fig. 23-9b, part 3, p. 825
Fig. 23-9, p. 825
Bronchi & lobules of lung
24
Alveoli Facts
Made mostly of Type I cells – Simple squamous epithelium
w/thin basal lamina
No cilia
Little muscle
0.2 – 0.5 mm in diameter
Huge surface area!
5% of cells are Septal cells -Type II
Round/cuboidal cells that secrete surfactant
Reduces surface tension
16. Contain macrophages
Have connecting pores
Alveolus (singular) – Alveoli (plural)
Fig. 22.9, Marieb, 6th ed.
Septal cell
Alveolar Blood Supply
Fig. 22.11 & 22.12, Saladin, 4th ed.
SEM of casts of alveoli & associated pulmonary capillaries
Fig. 22.9, Marieb, 6th ed.
Respiratory Membrane
Fig. 23-11, p. 825
Respiratory Membrane
Respiratory Membrane
Gases flow from high partial pressure to low partial pressure
Fig. 22.11, Saladin, 4th ed.
Fig. 23-12, p. 831
17. Fig 23.14, 892
Rest
Inhalation
Exhalation
Increased thoracic volume = lower pressure
Decreased thoracic volume = higher pressure
Respiratory Mechanics
How do we generate negative and positive pressures during
pulmonary ventilation?
23_14
Muscles of Respiration
Normal quiet respiration most involves diaphragm
Fig. 23-16, p. 836
Respiratory Muscles
31
Effect of rib & sternum movement on thoracic volume
Fig. 23.11, Seeley, 6th ed.; see fig 23-16 on p 836
Silverthorn, 4th ed., fig. 14-31
Saladin, 4th ed., fig. 22.16
18. 32
Muscles of Inspiration/ Expiration
Resting Expiration
Forced Expiration
Resting Inspiration
Forced Inspiration
Saladin, 4th ed., fig. 22.13
Shier, 11th ed., fig. 19.24 & 25
Respiratory Mechanics
Pulmonary Ventilation:
Inspiration – bring air into lung
Expiration – push air out of lung
Air moves from High pressure to Low pressure
Air movements into and out of lung driven by PRESSURE
GRADIENTS relative to the ATMOSPHERE
Thibodeau, 6th ed., fig. 24-3
34
How do we generate negative and positive pressures during
pulmonary ventilation?
Dependent on volume changes in the thoracic cavity
19. P = 1
V
Boyle’s Law
P1V1 = P2V2
P = pressure of gas (mm Hg)
V = volume of gas (mm3)
P1 = initial pressure, V1 = initial volume
P2 = resulting pressure, V2 = resulting volume
Fig. 23-13, p. 831
Pressure & volume are
inversely proportional
35
Lung spaces and pressures (at static conditions)
Marieb, 6th Fig. 22.12, see Fig. 23-15, left, p. 834
36
Pressure relationships in thoracic cavity
During static conditions, air pressure in alveoli = air pressure in
20. atmosphere
Atmosphere pressure = 760 mm Hg
Patm is assigned the value of 0 mm Hg
Alveolar ( or intrapulmonary, intrapulmonic) pressure = PPUL
(or PL)= 760 mmHg (at static conditions)
During inhalation, the PPUL becomes slightly -
During exhalation, the PPUL becomes slightly +
Air pressure in pleural cavity (intrapleural space = Pip) is
ALWAYS negative
Pip Always ~ 4 mm Hg less than PL
Keeps lungs from collapsing
Atmospheric Pressure 760 mm Hg (0 mm Hg)
37
chest wall
lung surface
pleural cavity
intrapleural pressure
(Pip = -4 mm Hg)
intrapulmonary pressure
21. (PL = 0 mm Hg)
atmospheric pressure = Pout = 0 mm Hg
Respiratory Pressures in Static Conditions
38
Why is the intrapleural pressure negative?
Interaction of opposing forces
Forces acting to collapse lung:
(1) Elasticity of lungs
(2) Alveolar surface tension
Breathing Mechanics
http://physproject-
2011.wikispaces.com/I.RESPIRATORY+PHYSIOLOGY
39
22. Why is the intrapleural pressure negative?
Interaction of opposing forces
Forces acting to collapse lung:
(1) Elasticity of lungs
(2) Alveolar surface tension
Force resisting lung collapse:
Forces equilibrate at Pip = -4 mm Hg
Surface tension of serous fluids keep lungs “stuck” to chest wall
(1) Rigid chest wall
Breathing Mechanics
40
Pneumothorax:
“sucking chest wound”
Breathing Mechanics
Silverthorn, 4th ed., fig. 14-31
http://scienceray.com/biology/human-biology/anatomy-of-
23. lungs-how-the-lungs-work/
41
Inspiration (quiet breathing):
Diaphragm
0 mm Hg
0 mm Hg
-4 mm Hg
Muscular expansion of the thoracic cavity
Breathing Mechanics
42
Inspiration (quiet breathing):
Muscular expansion of the thoracic cavity
(1) Contraction of diaphragm
Pushes liver down
Diaphragm
24. ? mm Hg
0 mm Hg
-? mm Hg
Breathing Mechanics
43
Inspiration (quiet breathing):
0 mm Hg
Muscular expansion of the thoracic cavity
(1) Contraction of diaphragm
Pushes liver down
(2) Contraction of ext. intercostal muscles
Expands thorax
Diaphragm
? mm Hg
0 mm Hg
-? mm Hg
Breathing Mechanics
44
25. Inspiration (quiet breathing):
0 mm Hg
Muscular expansion of the thoracic cavity
(1) Contraction of diaphragm
Pushes liver down
(2) Contraction of ext. intercostal muscles
Expands thorax
Results in:
Reduced intrapleural pressure
0 mm Hg
Diaphragm
? mm Hg
0 mm Hg
-8 mm Hg
Breathing Mechanics
45
Inspiration (quiet breathing):
0 mm Hg
Muscular expansion of the thoracic cavity
(1) Contraction of diaphragm
Pushes liver down
(2) Contraction of ext. intercostal muscles
Expands thorax
Results in:
26. Reduced intrapleural pressure
Reduced intrapulmonary pressure
0 mm Hg
Diaphragm
-1 mm Hg
0 mm Hg
-8 mm Hg
Breathing Mechanics
46
Inspiration:
0 mm Hg
Muscular expansion of the thoracic cavity
(1) Contraction of diaphragm
Pushes liver down
(2) Contraction of ext. intercostal muscles
Expands thorax
Results in:
Reduced intrapleural pressure
Reduced intrapulmonary pressure
Air enters lungs
0 mm Hg
27. Diaphragm
-1 mm Hg
0 mm Hg
-8 mm Hg
Breathing Mechanics
47
Expiration:
Retraction of the thoracic cavity
0 mm Hg
0 mm Hg
-1 mm Hg
0 mm Hg
-8 mm Hg
Diaphragm
Breathing Mechanics
Thibodeau, 6th ed., fig. 24-4
28. 48
Expiration:
Retraction of the thoracic cavity
(1) Passive Expiration (quiet)
Diaphragm relaxes
0 mm Hg
0 mm Hg
Diaphragm
? mm Hg
0 mm Hg
-? mm Hg
Breathing Mechanics
49
Expiration:
Retraction of the thoracic cavity
(1) Passive Expiration (quiet)
Diaphragm relaxes
Ext. intercostals relax
0 mm Hg
0 mm Hg
29. Diaphragm
? mm Hg
0 mm Hg
-? mm Hg
Breathing Mechanics
50
Expiration:
Retraction of the thoracic cavity
(1) Passive Expiration (quiet)
Diaphragm relaxes
Ext. intercostals relax
Elastic rebound
0 mm Hg
0 mm Hg
Diaphragm
? mm Hg
0 mm Hg
-? mm Hg
30. Breathing Mechanics
51
Expiration:
Retraction of the thoracic cavity
0 mm Hg
0 mm Hg
Diaphragm
1 mm Hg
0 mm Hg
-4 mm Hg
(1) Passive Expiration (quiet)
Diaphragm relaxes
Ext. intercostals relax
Elastic rebound
Results in increased pressure
in thoracic cavity and air exits
Breathing Mechanics
52
31. Expiration:
Retraction of the thoracic cavity
(1) Passive Expiration (quiet)
Diaphragm relaxes
Ext. intercostals relax
Elastic rebound
Active Expiration (forced)
0 mm Hg
0 mm Hg
Diaphragm
1 mm Hg
0 mm Hg
-4 mm Hg
Breathing Mechanics
53
Expiration:
Retraction of the thoracic cavity
0 mm Hg
0 mm Hg
32. Diaphragm
1 mm Hg
0 mm Hg
-4 mm Hg
(1) Passive Expiration (quiet)
Diaphragm relaxes
Ext. intercostals relax
Elastic rebound
(2) Active Expiration (forced)
Contraction of abdominal muscles
Breathing Mechanics
54
Expiration:
Retraction of the thoracic cavity
0 mm Hg
0 mm Hg
Diaphragm
> 1 mm Hg
0 mm Hg
-4 mm Hg
(1) Passive Expiration (quiet)
33. Diaphragm relaxes
Ext. intercostals relax
Elastic rebound
(2) Active Expiration (forced)
Contraction of abdominal muscles
Forces air out of lungs
Breathing Mechanics
55
Fig. 23-15, p. 834
Lung Pressures during a breath
56
Resistance to Airflow
Physical Factors Influencing Pulmonary Ventilation:
Airway resistance
Flow of air = change in pressure / resistance
Remember: R = 1 / radius4
Asthma - allergic response to irritants
34. 57
Resistance to Airflow continued…
Physical Factors Influencing Pulmonary Ventilation:
Surface tension in alveoli
Moist alveolar surfaces are attracted to one another (H2O
polarity)
Tends to collapse alveoli
Alveolar cells (type II) secrete surfactant detergent-like,
neutralizes tendency of alveoli to collapse
IRDS = Infant respiratory distress syndrome (premature birth)
58
Resistance to Airflow continued…
Physical Factors Influencing Pulmonary Ventilation:
3. Lung Compliance
“Stretchiness” of the lung (e.g. distensibility)
Compliance diminished by factors which:
Reduce resilience of lung
Block smaller passages
Reduce surfactant production
Decrease flexibility of thoracic cage
35. 59
Fig. 23-9a, p. 825
Anatomical dead space
alveolar ventilation
Silverthorn, 4th ed., fig. 14-31
60
500 ml
Respiratory Volumes
Tidal Volume (normal breathing): ~500 ml @ rest
Inspiratory Reserve Volume
Forced inspiration
Expiratory Reserve Volume
Forced expiration
Residual Volume
Keeps alveoli open
Prevents lung collapse
Can exchange up to ~4800 ml, as needed
Volume (ml)
2100 - 3200 ml
1000 - 1200 ml
36. 1200 ml
The following slides are modified from Fig 23-17
61
Respiratory Rates & Capacities
Fig. 23-17, p. 838
Respiratory rate (f) - # breaths/minute
Respiratory minute volume (VE) = total amount (ml) of air that
flows in/out resp. tract/minute:
VE = f x VT
= VT
62
Respiratory Capacities
Inspiratory Capacity
Total amount of inspired air after tidal expiration
Functional Residual Capacity
Amount of air in lungs following tidal expiration
Vital Capacity (~4800 ml)
Total amount of exchangeable air
Total Lung Capacity (~6000 ml)
Sum of all lung volumes
37. 500 ml
Volume (ml)
2100 - 3200 ml
1000 - 1200 ml
1200 ml
IC
FRC
VC
TLC
63
Cough - Dislodge/propel foreign substances/mucus (lower
respiratory)
Sneeze
Clears upper respiratory tract (nasal cavity)
Crying/Laughing
Emotionally induced mechanism
Hiccup
Irritation of diaphragm/phrenic nerve
Yawn
Ventilates all alveoli
Nonrespiratory Air Movements
38. 64
Marieb 6th Fig 22.13
Pulmonary Ventilation Summary
65
Respiration Includes:
Pulmonary ventilation
Pumping air in/out of lungs
External respiration
Gas exchange at blood-gas barrier in lung
Transport of respiratory gases by blood
Internal respiration
Gas exchange at tissues
Thibodeau, 6th ed., fig. 24-1
66
Respiratory Gases:
Why do we need O2 & Where does CO2 come from?
Oxygen (O2) is used to make ATP
Carbon dioxide (CO2) is waste product of aerobic metabolism
Produced in tissues
Expelled in lungs
Glucose
40. Carbon
Dioxide
Water Vapor 4.6%
Partial pressure is the pressure that an individual gas of a
mixture contributes to the overall mixture’s pressure
(part/whole)
Fig. 24.14, Thibodeau, 6th ed.
Marieb, 6th ed.
68
How can we express percentage as partial pressure?
Dalton’s Law of Partial Pressures:
PAtmosphere = 760 mm Hg
PO2 = 0.21 x 760 mm Hg = 159 mm Hg
PN2 = 0.79 x 760 mm Hg = 597 mm Hg
PCO2 = 0.0004 x 760 mm Hg = 0.30 mm Hg
% Composition of Air
20.94%
Oxygen
79%
Nitrogen
0.04%
Carbon
Dioxide
Water Vapor 4.6%
41. The total pressure of a gas is equal to the sum of the pressures
of its constituents
69
Composition of Air
159 mmHg
Oxygen
597 mmHg
Nitrogen
0.3 mmHg
Carbon
Dioxide
Water Vapor 3.7 mmHg
N2 = 569 mmHg
H2O = 47 mmHg
O2 = 104 mmHg
CO2 = 40 mmHg
Composition of Lung Air
Marieb, 6th ed.
42. 70
How do O2 & CO2 move between the alveolar air and the blood
stream ?
Henry’s Law:
Gases diffuse down their pressure gradient
Gases in a mixture dissolve into a liquid in proportion to their
partial pressures until equilibrium
Fig 23.18, 840
Fig. 23-13, p. 831
71
How do Oxygen & Carbon Dioxide move between the alveolar
air and the blood stream?
Other factors affecting gas/liquid interchange:
Solubility of gas in a given medium
For water,
Carbon Dioxide >> Oxygen >> Nitrogen
Temperature
Solubility inversely related to temperature
72
Solubility of Oxygen & Carbon Dioxide in blood
Oxygen solubility in blood is increased from 1.5% to 20% by
43. hemoglobin
Arterial blood has PO2 = ~100 mmHg
Venous blood has PO2 = ~40 mmHg
Solubility of carbon Dioxide results in:
Venous blood has PCO2 = ~45 mmHg
Arterial blood has PCO2 = ~40 mmHg
O2
CO2
Fig. 22.18, Saladin, 4th ed.
73
Partial Pressures of gases in lungs, tissues & bloodPO2
(mmHg)PCO2 (mmHg)Air in1600.3Alveoli
10440Tissues4045Air out12027
Tissue PO2 & PCO2 =
Venous blood PO2 & PCO2
Alveoli PO2 & PCO2 =
Arterial blood PO2 & PCO2
Fig. 22.19, Saladin, 4th ed.
74
Factors controlling Alveolar Gas Exchange:
44. External Respiration (O2/CO2 exchange between blood and
lungs)
Pulmonary gas exchange driven by gas partial pressures
PO2 in alveoli = ~100 mmHg
PO2 in blood = ~40 mmHg
Net movement into blood
PCO2 in alveoli = ~40 mmHg
PCO2 in blood = ~45 mmHg
Net movement into alveoli
Thin, extensive exchange area maximizes transport rates
across blood/gas barrier
Ventilation-perfusion coupling
Time blood in contact with alveoli does not affect gas exchange
Marieb, 6th ed. Fig. 22.19
Equilibrium Achieved
75
Factors controlling Alveolar Gas Exchange: Ventilation-
perfusion coupling
Marieb, 6th ed. Fig. 22.19
Mechanism for matching the flow of blood with the volume of
gas that reaches the alveoli (Autoregulatory homeostasis)
Ventilation = amount of gas reaching alveoli
2) Perfusion = blood flow in pulmonary capillaries
76
Factors controlling Tissue Gas Exchange:
45. Internal Respiration (O2/CO2 exchange between
blood and tissue)
Systemic gas exchange also driven by gas partial pressures
PO2 in arterial blood = ~100 mmHg
PO2 in tissue = ~40 mmHg
Net movement into tissue
PCO2 in arterial blood = ~40 mmHg
PCO2 in tissue = ~45 mmHg
Net movement into blood
Thin exchange area maximizes transport rates across
blood/tissue barrier
Tissue levels of CO2, temperature & pH
77
Gas Transport – O2 Transport
Most O2 in blood bound to hemoglobin (Hb)
O2 solubility low in plasma (~ 1.5%)
> 98.5% of O2 bound to hemoglobin
Hb can bind up to 4 O2 molecules (saturated)
Fig 19.3, 646
Silverthorn, 4th ed., fig. 18.7
78
Gas Transport – O2 Transport
HHb = deoxyhemoglobin (reduced)
Hb after O2 released
46. HbO2 = oxyhemoglobin (oxidized)
Hb carrying O2
HHb + O2 HbO2 + H+
lungs
tissues
(HHb = Hb bound to H+)
Shier, 11th ed., fig. 19.35
79
Gas Transport – O2 Transport
O2 association/dissociation w/Hb depends on # of O2 molecules
present
Cooperative binding (lungs)
As each Hb subunit binds 1 O2, the affinity of Hb for binding
O2 ↑
Reversible binding (tissues)
Bond between Hb & molecular O2 very loose
Offloading of 1 molecule enhances offloading of another
For each molecule of O2 bound, Hb is said to be 25% saturated
If 3 molecules of O2 bound, Hb is 75% saturated
Fig 19.3, 646
47. 80
Gas Transport – O2 Transport in Lungs
% of O2 saturation depends on body environment PO2
Oxygen-Hb Dissociation Curve
Sigmoid Curve
(Cooperative binding)
PO2 ~ 100 mm Hg
(alveolar PO2)
Hb 98% saturated w/O2
20 ml O2/100 ml blood
(Oxygen content=20 vol %)
Body Environment PO2
% O2 saturation of hemoglobin
0
20
40
60
80
100
20
40
60
80
100
20
15
10
5
48. ml O2 / 100 ml blood
Lungs
HHb + O2 HbO2 + H+
81
Gas Transport – O2 Transport in Tissues
% of O2 saturation depends on body environment PO2
Oxygen-Hb Dissociation Curve
Sigmoid Curve
(reversible binding)
PO2 ~ 40 mm Hg
(Tissue PO2)
Hb 75% saturated w/O2
15 ml O2/100 ml blood
(Oxygen content = 15 vol %)
Body Environ. PO2
% O2 saturation of hemoglobin
0
20
40
60
80
49. 100
20
40
60
80
100
20
15
10
5
ml O2 / 100 ml blood
Tissues (Rest)
HHb + O2 HbO2 + H+
82
Gas Transport – O2 Transport
% of O2 saturation depends on body environment PO2
Oxygen-Hb Dissociation Curve
Only 25% O2 unloaded
during systemic circuit
Venous reserve
Hb saturated at 70 mm Hg
50. Adapted for varying PO2
% O2 saturation of hemoglobin
0
20
40
60
80
100
20
40
60
80
100
20
15
10
5
ml O2 / 100 ml blood
Volume of O2
unloaded to tissues
Tissues (Rest)
Body Environ. PO2
51. 83
Gas Transport – O2 Transport
Enhanced oxygen offloading during exercise:
Body environment PO2 in exercising tissue drops 20-25 mm Hg
Body Environment PO2
% O2 saturation of hemoglobin
0
20
40
60
80
100
20
40
60
80
100
20
15
10
5
ml O2 / 100 ml blood
Volume of O2
unloaded to rest tissues
52. Exercise Tissues
Volume of O2
unloaded to rest tissues
Only 25% O2 unloaded in systemic circuit at rest
About 70% O2 unloaded in systemic circuit during
exercise w/small shift in tissue PO2
Resting Tissues
84
Gas Transport – O2 Transport
Factors acting on Oxygen Transport:
Multiple factors influence O2 affinity of Hb (modify structure)
Temperature
↑ Temperature =
↓ O2 affinity =
Shift curve right
PO2 (mm Hg)
Marieb, 6th ed. Fig 22.21
85
53. Gas Transport – O2 Transport
Factors acting on Oxygen Transport: Multiple factors influence
O2 affinity of Hb (modify structure)
pH (Bohr effect)
↓ pH (more acidic) = ↓ O2 affinity = Shift curve right
PCO2
↑ PCO2 = ↓ O2 affinity = Shift curve right
Fig 23.19, Seeley, 6th ed.
86
Gas Transport – O2 Transport
Factors acting on Oxygen Transport: Multiple factors influence
O2 affinity of Hb (modify structure)
Temperature
↑ Temperature =↓ O2 affinity
pH (Bohr effect)
↓ pH (more acidic) =↓ O2 affinity
PCO2
↑ PCO2 =↓ O2 affinity
BPG (2, 3-bisphosphoglycerate)
Intermediate of anaerobic metabolism (produced by RBC’s)
↑ BPG =↓ O2 affinity
Fig 40.10, Guyton, 11th ed.
McKinley, Figure 23.29
54. 87
Gas Transport–O2 Transport
“Adaptive Complex” - During extreme physical activity:
Temperature ↑
pH ↓
PCO2 ↑
BPG ↑
All facilitate unloading
of O2 at tissues...
Thibodeau, 6th ed., fig. 24.28
88
How does gas transfer occur in lungs & tissues?
McKinley, Figure 23.27
89
O2 Exchange: Lung to Blood
Red Blood Cell
56. HHb + O2
HbO2 + H+
98.5%
1.5%
90
O2 Exchange: Blood to Tissue
Red Blood Cell
Tissue
57. PO2
40 mm Hg
Blood
PO2
100 mm Hg
O2
O2
O2
O2
O2
O2
HHb + O2
HbO2 + H+
1.5%
98.5%
91
Overview of CO2 Transport
CO2 carried in blood 3 ways:
1. Dissolved directly in plasma: 7-10%
2. Bound to amino acids of Hb (NOT bound to heme like O2):
20-30%
=Carbaminohemoglobin (HbCO2)
CO2 +
3.Converted to bicarbonate ion (HCO3-): 60-70%
Fig. 23.24, 846
58. 92
Gas Transport – CO2 Transport
CO2 Transport as bicarbonate:
CO2
+
H2O
H2CO3
(1) Carbon dioxide (CO2) combines with water (H2O) to
form carbonic acid (H2CO3) in RBCs
Reaction catalyzed by carbonic anhydrase (CA)
CA
FAST
93
Gas Transport – CO2 Transport
CO2 Transport as bicarbonate:
CO2
+
H2O
H2CO3
(1) CO2 combines with H2O to form H2CO3 in RBCs
59. H+
+
HCO3-
(2) H2CO3 dissociates into hydrogen ion (H+) and
bicarbonate ion (HCO3-)
HCO3- released into plasma (balanced by Cl- shift)
Plasma
H+ binds to Hb (Bohr effect - lowers O2 affinity)
Remember: HHb + O2 HbO2 + H+
Hb
CA
FAST
94
CO2 Exchange: Tissue to Blood
Red Blood Cell
62. CO2 Exchange: Blood to lung
Red Blood Cell
Alveoli
PCO2
40 mm Hg
Blood
PCO2
45 mm Hg
Cl-
Cl-
HCO3-
CO2 + H2O
H2CO3
H+ + HCO3-
Slow
CO2
CO2
CO2
CO2 + H2O
64. O2 / CO2 Exchange Interactions
Tissue
PCO2
45 mm Hg
Blood
PCO2
40 mm Hg
PO2
40 mm Hg
PO2
100 mm Hg
Red Blood Cell
CO2 + H2O
H2CO3
H+ + HCO3-
CA
CO2
O2
HHb + O2
HbO2 + H+
Fast
Cl-
Cl-
HCO3-
65. 97
O2 / CO2 Exchange Interactions
Alveoli
PCO2
40 mm Hg
Blood
PCO2
45 mm Hg
PO2
66. 100 mm Hg
PO2
40 mm Hg
Red Blood Cell
CO2 + H2O
H2CO3
H+ + HCO3-
CA
CO2
O2
HHb + O2
HbO2 + H+
Fast
Cl-
Cl-
HCO3-
98
Control of Respiration
Medullary Respiratory Centers (reticular formation)
Ventral Respiratory Group (VRG)
Inspiratory Center (IC)
67. “pacesetter:” 12-15 breaths/min; eupnea
Expiratory center
Mixed innervation (inspiration/ expiration)
Role in forced expiration
Dorsal Respiratory Group (DRG)
Integrates info from peripheral stretch & chemoreceptors
Marieb & Hoehn – Figure 21.23
Phrenic Nerve Controls Diaphragm
99
Control of Respiration
Pontine Respiratory Centers (Pons)
Modulates respiratory rhythm
Fine-tuning
Smooth out transitions
Marieb & Hoehn – Figure 21.23
100
Control of Respiration
Neural & chemical influences on respiratory centers
Signals from the limbic system & hypothalamus
Chemoreceptors
Detect changes in blood PO2, PCO2 & pH (H+)
Central chemoreceptors in brainstem
Peripheral chemoreceptors in arteries
Pulmonary Irritant Reflexes (Protective Reflex)
Inflation Reflex or Hering-Breuer Reflexes
Prevents lung over-inflation
68. Marieb & Hoehn – Figure 21.24
Which chemical stimulant do you think will be the most
important?
101
Control of Respiration: Chemoreceptor reflexes
[PCO2]: Most Powerful Respiratory Stimulant (indirect)
Mediated through central chemoreceptors (mostly)
↑ CO2 = hypercapnia
↓ CO2 = hypocapnia
↑ CO2 = ↑ H+ in CSF = ↑ ventilation rate
Hypercapnia leads to Hyperventilation
Hypocapnea leads to Hypoventilation, apnea
Marieb & Hoehn – Figure 21.24
Remember:
-
Marieb & Hoehn – Figure 21.25
Control of Respiration: Chemoreceptor reflexes
103
69. Martini – Figure 23-27
Control of Respiration: Chemoreceptor reflexes
ventral
ventral
104
[PCO2]: Most Powerful Respiratory Stimulant (indirect)
[PO2]: Minor Respiratory Stimulant
Mediated through peripheral chemoreceptors
Located in aorta & carotid arteries
Stimulated by [PO2] < 60 mm Hg
Hypoxic drive
Marieb & Hoehn – Figure 21.26
Control of Respiration: Chemoreceptor reflexes
105
[PCO2]: Most Powerful Respiratory Stimulant (indirect)
[PO2]: Minor Respiratory Stimulant
Arterial pH
Mediated through peripheral chemoreceptors
↓ pH = ↑ Respiratory Rate
Control of Respiration: Chemoreceptor reflexes
Marieb & Hoehn – Figure 21.24
