1. Why oxygen is import
Most animals satisfy their energy requirement by oxidation of food, in the processes forming carbon dioxide and water
Oxygen is most abundant element in the earth’s crust (49.2%)
In atmosphere Per liter water (150C, 1 atm)
O % ml
CO % ml
N % ml
Argon %
Total 100%

2. Vacuum
760 mm
Pressure exerted by
atmospheric air above
Earth’s surface
Pressure at
sea level
Mercury (Hg)

3. Oxygen and carbon dioxide in physical environment
Oxygen is added to atmosphere:
Photosynthesis (dominant)
Photodissociation of water vapor
Oxygen is removed from atmosphere:
Living organism respiration
Oxidizing of organic matter, rocks, gases and fossil fuels

4. "Global warming" is a real phenomenon: Earth's temperature is increasing.
True
False

7. Fig. 11-2, p.464

9. Oxygen and carbon dioxide in physical environment
Solubility of oxygen decreases with increasing water temperature and salinity
Temperature Fresh water Sea water
ml O2/L water ml O2/L water
Normoxic water: 100% saturated with oxygen
Hypoxic water contains less oxygen than normoxic water
Anoxic water contains no dissolved oxygen

12. Transport O2 and CO2 in living systems
Diffusion is common mechanism for transport both O2 and CO2 across the body surface
To maximize the rate of gas transfer
Large respiratory surface area
Small diffusion distance

14. The lungs contain many branching airways which collectively are known as the bronchial tree

15. • The trachea and all the bronchi have supporting cartilage which keeps the airways open.
• Bronchioles lack cartilage and contain more smooth muscle in their walls than the bronchi, for airflow regulation
• The airways from the nasal cavity through the terminal bronchioles are called the conducting zone.
The air is moistened, warmed, and filtered as it flows through these passageways.

17. The pulmonary arteries carry blood which is low in oxygen from the heart to the lungs.
• These blood vessels branch repeatedly, eventually forming dense networks of capillaries that completely surround each alveolus.
• oxygen and carbon dioxide are exchanged between the air in the alveoli and the blood in the pulmonary capillaries.
• Blood leaves the capillaries via the pulmonary veins, which transports the oxygenated blood out of the lungs and back to the heart.

18. Alveoli ~ 300 million air sacs. Large surface area (60 – 80 m2).
Each alveolus is 1 cell layer thick.
Total air barrier is 2 cells across (0.5 mm).
3 types of cells:
Alveolar type I:
Structural cells.
Alveolar type II:
Secrete surfactant.

19. Ventilation Mechanical process to move air in and out of the lungs.
O2 of air is higher in the lungs than in the blood, O2 diffuses from air to the blood.
C02 moves from the blood to the air by diffusing down its concentration gradient.
Gas exchange occurs entirely by diffusion.
Diffusion is rapid because of the large surface area and the small diffusion distance.

20. 1. simple epithelium cells 2. alveolar macrophages
Three types of cells:
1. simple epithelium cells
2. alveolar macrophages
3. surfactant-secreting cells
• The wall of an alveolus is primarily composed of simple epithelium, or Type I cells. Gas exchange occurs easily across this very thin epithelium.
• The alveolar macrophages, or dust cells, creep along the inner surface of the alveoli, removing debris and microbes.
• The alveolus also contains scattered surfactant-secreting, or Type II, cells.

21. • Water in the fluid creates a surface tension.
Surface tension is due to the strong attraction between water molecules at the surface of a liquid, which draws the water molecules closer together.
• Surfactant, which is a mixture of phospholipids and lipoproteins, lowers the surface tension of the fluid by interfering with the attraction between the water molecules, preventing alveolar collapse.
• Without surfactant, alveoli would have to be completely reinflated between breaths, which would take an enormous amount of energy.

22. • The wall of an alveolus and the wall of a capillary form the respiratory membrane, where gas exchange occurs.

24. Summary
• The lungs contain the bronchial tree, the branching airways from the primary bronchi through the terminal bronchioles.
• The respiratory zone of the lungs is the region containing alveoli, tiny thin-walled sacs where gas exchange occurs.
• Oxygen and carbon dioxide diffuse between the alveoli and the pulmonary capillaries across the very thin respiratory membrane.

25. Three main factors:
1.The surface area and structure of the respiratory membrane.
2. Partial pressure gradients
3. Matching alveolar airflow to pulmonary capillary blood flow

26. Atmosphere
760 mm Hg
Atmospheric pressure (the pressure
exerted by the weight of the gas in the
atmosphere on objects on the Earth’s
surface—760 mm Hg at sea level)
Airways (represents all airways collectively)
Thoracic wall
(represents entire thoracic cage)
Intra-alveolar pressure (the pressure within
the alveoli—760 mm Hg when equilibrated
with atmospheric pressure)
760 mm Hg
Pleural sac
(space represents pleural cavity)
756 mm Hg
Lungs (represents all alveoli collectively)
Intrapleural pressure (the pressure within
the pleural sac—the pressure exerted
outside the lungs within the thoracic
cavity, usually less than atmospheric
pressure at 756 mm Hg)
Fig , p.480

27. (greatly exaggerated) Lung wall
760
Airways
Pleural cavity
(greatly exaggerated)
Lung wall
Lungs (alveoli)
Thoracic wall
756
756
760
760
760
756
Transmural pressure gradient
across lung wall =
intra-alveolar pressure minus
intrapleural pressure
Transmural pressure gradient
across thoracic wall =
atmospheric pressure minus
intrapleural pressure
Numbers are mm Hg pressure.
Fig , p.481

29. Accessory muscles of inspiration (contract only during forceful
Internal
intercostal
muscles
Sternocleidomastoid
Scalenus
Sternum
Ribs
Muscles
of active
expiration
(contract only
during active
expiration)
External
intercostal
muscles
Diaphragm
Major
muscles of
inspiration
(contract every
inspiration;
relaxation
causes passive
expiration)
Abdominal
muscles
Fig , p.482

30. External
intercostal
muscles
(relaxed)
Elevated
rib cage
Elevation of ribs causes sternum
to move upward and outward, which
increases front-to-back dimension
of thoracic cavity
Contraction
of external
intercostal
muscles
Sternum
Contraction of
diaphragm
Diaphragm
(relaxed)
Before inspiration
Inspiration
Lowering of diaphragm on
contraction increases vertical
dimension of thoracic cavity
Contraction of external intercostal
muscles causes elevation of ribs,
which increases side-to-side
dimension of thoracic cavity
(a)
Fig a, p.483

31. Contraction of internal intercostal muscles
flattens ribs and sternum, further reducing
side-to-side and front-to-back dimensions
of thoracic cavity
Relaxation
of external
intercostal
muscles
Contraction
of internal
intercostal
muscles
Relaxation of
diaphragm
Contraction of
abdominal
muscles
Position of
relaxed
abdominal
muscles
Passive expiration
Active expiration
Return of diaphragm, ribs, and sternum
to resting position on relaxation of
inspiratory muscles restores thoracic
cavity to preinspiratory size
Contraction of abdominal muscles
causes diaphragm to be pushed
upward, further reducing vertical
dimension of thoracic cavity
(b)
(c)
Fig bc, p.483

33. H2O molecules
An alveolus
Fig , p.486

34. Fig , p.489

35. Fig , p.490

40. Factors affecting the exchange of oxygen and carbon dioxide during internal respiration:
1.The available surface area
2. Partial pressure gradients.
3. The rate of blood flow in a specific tissue.

41. • These gases are carried in several different forms:
Oxygen and Carbon Dioxide Transportation
• The blood transports oxygen and carbon dioxide between the lungs and other tissues throughout the body.
• These gases are carried in several different forms:
1. dissolved in the plasma
2. chemically combined with hemoglobin
3. converted into a different molecule

43. Hemoglobin and 02 Transport
280 million hemoglobin/ RBC.
Each hemoglobin has 4 polypeptide chains and 4 hemes.
Each heme has 1 atom iron that can combine with 1 molecule O2
Each hemoglobin can combine with 4 molecule O2
Combine reversibly with O2 depend on PO2

44. Hemoglobin's affinity for oxygen increases as its saturation increases
the affinity of hemoglobin for oxygen decreases as its saturation decreases

45. Hemoglobin Oxyhemoglobin: Deoxyhemoglobin:
Normal heme contains iron in the reduced form. Reduced form of iron can share electrons and bond with oxygen.
Deoxyhemoglobin:
When oxyhemoglobin dissociates to release oxygen, the heme iron is still in the reduced form.

46. Hemoglobin Hemoglobin production controlled by erythropoietin.
Production stimulated by P02 delivery to kidneys.
Loading/unloading depends:
P02 of environment.
Affinity between hemoglobin and 02.

47. Oxyhemoglobin Dissociation Curve
Oxygen dissociation curve describes the relation between percent of saturation and the partial pressure of oxygen (S-shape, sigmoid)
At high PO2, a large amount of O2 is bound
At low PO2, only small amount of O2 is bound

48. Hemoglobin saturation is determined by the partial pressure of oxygen
S-shaped curve

51. Oxyhemoglobin Dissociation Curve
Loading and unloading of 02.
Steep portion of the curve, small changes in P02 produce large differences in % saturation (unload more 02).
Decreased pH, increased temp., and increased 2,3 DPG, increase CO2 affinity of Hb for 02 decreases.
Shift to the right greater unloading.
Bohr effect

53. Muscle Myoglobin
Slow-twitch skeletal fibers and cardiac muscle cells are rich in myoglobin.
Has a higher affinity for 02 than hemoglobin.
Acts as a “go-between” in the transfer of 02 from blood to the mitochondria within muscle cells.
May also have an 02 storage function in cardiac muscles.

54. Human fetal hemoglobin contains g chains, which has a high O2 affinity than adult b hemoglobin
In humans, the oxygen affinity of blood decrease for about 3 months after the birth

57. This reaction is catalyzed by the enzyme carbonic anhydrase.

58. C02 Transport C02 transported in the blood: HC03- (70%).
Dissolved C02 (7%).
Carbaminohemoglobin (23%).
HCO3- is high in plasma than in erythrocytes
CO2 enters and leaves the blood as molecular CO2 rather than HCO3-

59. Chloride Shift at Systemic Capillaries
H20 + C H2C H+ + HC03-
At the tissues, C02 diffuses into the RBC, reaction shifts to the right.
Increased [HC03-] in RBC, HC03- diffuses into the plasma with assistance of band III protein.
RBC becomes more +.
Cl- diffuses in (Cl- shift).
HbC02 formed, give off 02.

60. At Pulmonary Capillaries
H20 + C H2C H+ + HC03-
At the alveoli, C02 diffuses into the alveoli, reaction shifts to the left.
Decreased [HC03-] in RBC, HC03- diffuses into the RBC.
RBC becomes more -.
Cl- diffuses out (Cl- shift).
Hb02 formed, give off HbC02.

63. Summary
• O2 is transported in two ways:
• dissolved in plasma, and
• bound to hemoglobin as oxyhemoglobin
• The O2 saturation of hemoglobin is affected by:
• PO2, pH , temperature, PCO2, and DPG
CO2 is transported in three ways:
• dissolved in plasma, bound to hemoglobin as carbaminohemoglobin, and converted to bicarbonate ions
Oxygen loading facilitates carbon dioxide unloading from hemoglobin. This is known as the Haldane effect.
• When the pH decreases, carbon dioxide loading facilitates oxygen unloading. The interaction between hemoglobin's affinity for oxygen and its affinity for hydrogen ions is called the Bohr effect.

64. Pons Pons Pneumotaxic center respiratory centers Apneustic center
Pre-Bötzinger
complex
Respiratory
control
centers in
brain stem
Dorsal respiratory
group
Medullary
respiratory
center
Medulla
Ventral respiratory
group
Fig , p.513

65. + + Input from other areas–– some excitatory, some inhibitory
Inspiratory neurons
in DRG
(rhythmically firing)
Medulla +
Spinal cord
Phrenic nerve +
Diaphragm
Not shown are intercostal nerves to external intercostal muscles.
Fig , p.513

66. Sensory Sensory nerve fiber nerve fiber Carotid sinus Carotid bodies
Carotid artery
Aortic bodies
Aortic arch
Heart
Fig , p.514

67. _ + + Arterial PO2 < 60 mm Hg No effect on Peripheral
Emergency
life-saving
mechanism + No
effect on
Peripheral
chemoreceptors
Medullary
respiratory
center
Central +
Ventilation
Arterial PO2
Fig , p.515

68. Fig , p.516