1. Mechanics of Breathing

2. Introduction Pulmonary ventilation:
Moving air into and out of the lungs
Breathing
Inspiration = moving air into the lungs
Expiration = moving air out of lungs

4. Pressure Relationships
Intrapulmonary pressure
Pressure within the alveoli (lungs)
Changes with phases of breathing
Always equalizes itself with atmospheric pressure
Intrapleural pressure
Pressure within intrapleural space
Always 4mmHg less than intrapulmonary pressure

5. Atalectasis
Any conditions that causes intrapulmonary pressure to equal intrapleural pressure will cause the lungs to collapse
This means they lose the ability to move air since there is NO more pressure difference
pneumothorax – air in the intrapleural space due to trauma

6. Atelectasis

7. Pulmonary ventilation
Question: Why does breathing happen?
ONLY acceptable answer: Volume changes lead to pressure changes which lead to the flow of gases to equalize the pressure

8. Inspiration Main inspiratory muscles
Diaphragm & external intercostals
Thoracic dimensions change to increase volume of thoracic cavity by 0.5 liters
Intrapulmonary pressure drops 1-3 mmHg and air rushes info normal quiet inspiration
A deep forced inspiration requires activation of accessory muscles

9. Expiration A passive process dependent on natural lung elasticity
The lungs recoil, volume decreases, alveoli compress, intrapulmonary pressure rises, gas outflows to equalize the pressure with atmospheric pressure
Forced expiration requires contraction of muscles of the abdominal wall

11. Physical factors influencing
Pulmonary ventilation can be influenced by 4 physical factors
Respiratory passage resistance
Lung compliance
Lung elasticity
Alveolar surface tension forces

12. Respiratory passage resistance
Friction as air moves through passages
Smooth muscle bronchoconstriction and,
Local accumulations of mucus, infectious material, and tumors will cause the air flow to be reduced
Disorders such as asthma

13. Lung compliance The ease with which lungs can readily expand
Affected by the elasticity of the lungs and the thoracic cage
Diminished by 3 main factors:
Fibrosis of the lung tissue
Ossification and/or muscle paralysis impairs flexibility of the thoracic cage
Blockage of the passageways

14. Lung fibrosis

15. Lung Elasticity Essential for normal expiration
Emphysema: tissue becomes less elastic and more fibrous
Read ALL the imbalances and info about emphysema within your handout

17. Page 415 in text

18. Alveolar Surface Tension Forces
Surface tension – molecules of liquid hold together with hydrogen bonds
Surfactant – substance which interferes with cohesion of water molecules so less energy is needed to expand the lungs
IRDS – Infant Respiratory Distress Syndrome – read imbalance

19. Type II Cells

20. End of Quiz #3 Material

21. Gas Exchanges in the Body

22. Gas Exchanges Occur: Between the blood and the alveoli AND
Between the blood and the tissue cells
Takes place by simple diffusion
Depends on partial pressures of oxygen & carbon dioxide
That exist on opposite sides of the exchange membrane
Diagrams on page of text

23. Dalton’s Law
Total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas
(Ptotal = P1 + P2 + P3 + …)
The partial pressure of each gas is directly proportional to its % in the mixture
N2: 78.08%, O2: 20.95%, CO2: 0.04%

25. Henry’s law
Each gas will dissolve in a liquid in proportion to its partial pressure and solubility coefficient of the liquid
CO2 = .57
O2 = .024
N2 = .012
Solubility increases with increasing partial pressure
Solubility decreases with increasing temperature

27. Hyperbaric Conditions
Hyperbaric oxygen chambers – designed to force greater amounts of oxygen into patient’s blood

29. Life Applications Write down in detail the things we discuss!!!!
Oxygen toxicity
Nitrogen narcosis
Decompression sickness
High altitude sickness

30. Now what would happen if you breathed 100 percent oxygen?
Exposed to 100 percent oxygen at normal air pressure for 48 hours
A highly reactive form of the oxygen molecule, called a free radical destroys proteins and membranes in the epithelial cells.

31. In humans breathing 100 percent oxygen at normal pressure, here's what happens:
Fluid accumulates in the lungs.
Gas exchange in the alveoli slows down so person has to breathe more to get enough oxygen.
Volume of exchangeable air decreases by 17 percent.

32. SCUBA
In contrast, when 100 percent oxygen is breathed under high pressure (more than four times that of atmospheric pressure), acute oxygen poisoning can occur with these symptoms:
Nausea
Dizziness
Muscle twitches
Blurred vision
Seizures/convulsions
Such high oxygen pressures can be experienced by military SCUBA divers using rebreathing devices, divers being treated for the bends in hyperbaric chambers or patients being treated for acute carbon monoxide poisoning. These patients must be carefully monitored during treatment.

33. Nitrogen Narcosis
As the total gas pressure increases with increasing dive depth,
the partial pressure of nitrogen increases
more nitrogen becomes dissolved in the blood.
This high nitrogen concentration impairs the conduction of nerve impulses and mimics the effects of alcohol or narcotics.

34. Symptoms of nitrogen narcosis include:
Wooziness
Giddiness
Euphoria
Disorientation
loss of balance
loss of manual dexterity
slowing of reaction time
fixation of ideas
impairment of complex reasoning.
These effects are exacerbated by cold, stress, and a rapid rate of compression.

35. Decompression Sickness (the bends)
As pressure increases, solubility of gases increase
Larger quantities of Nitrogen are forced into the body fluid/blood but not used by the body
Ascending rapidly causes nitrogen gas to become less soluble and “bubble” out of the blood too fast to be exhaled

36. Decompression sickness
Gas collected in joint spaces and can also cause air embolisms which can lead to heart attack & stroke
Treatment:
Hyperbaric chamber
Take back down to depth & bring up slowly

37. Internal & External Respiration

38. Factors influencing internal & external respiration
Partial pressure gradients and gas solubilities cont’
Oxygen = has low solubility but steep partial pressure gradient (104 mmHg in alveoli – 40 mmHg in blood = 64 mmHg pressure gradient)
Carbon dioxide = has solubility ~20x greater than oxygen but partial pressure gradient is only 5 mmHg

39. Factors influencing internal & external respiration
Partial pressure gradients and gas solubilities
Due to the ratios of solubility coefficients and pressure gradients:
~Equal amounts of gases are exchanged
pH is not affected
H2O + CO2 = H2CO3 (carbonic acid)

40. Factors influencing internal & external respiration
Thickness of respiratory membranes
0.5 to 1.0 micrometers
Hypoxia = oxygen deprivation
Thickness – edematous (swollen) tissue can be caused by congestion and pneumonia
Emphysema – infections can thicken membranes

41. Factors influencing internal & external respiration
Surface Area
70-80 square meters for gas exchange
Emphysema
Walls of alveoli break down
Less surface area to volume ratio

42. Transport of respiratory gases

43. Oxygen Transport
Most oxygen is bound to hemoglobin for transport (blood is cherry red)
Vocabulary to understand
Loading = binding oxygen to hemoglobin for transport
Unloading = releasing oxygen from hemoglobin to go into tissue cells

47. Factors affecting hemoglobin transport
Affects unloading rate
20-25% of oxygen unloaded to tissues in one systemic circuit
Leaves a venous reserve of 75%
This is why brain death will begin to occur 3-4 minutes after your heart stops
CPR must begin ASAP!!

48. Factors affecting hemoglobin transport
As the temperature increases – oxygen unloading increases
Hard working tissues = high metabolism rate = heat produced = more oxygen unloaded
Hard working tissues need more oxygen to produce more ATP = the heat is one way the tissues signal the body to bring more oxygen
Cold tissues = low metabolism = less oxygen unloaded
Nose & Cheeks are red when cold because the body is trying to bring them a little more heat = no additional oxygen is unloaded in this case

49. Factors affecting hemoglobin transport
Active tissues = made lots of ATP so lots of carbon dioxide and hydrogen ions have been produced as a waste product = acidosis = increased oxygen unloading
CO2 + H2O = H2CO3 (carbonic acid)
Know the types of hypoxia and the symptoms & treatment of CO (fix this in notes) poisoning – see handout
Also read the bracketed info on page 743 of handout

50. Carbon Monoxide poisoning

51. Carbon dioxide transport
7% dissolved in plasma
~20% bound to hemoglobin – aka. Carbaminohemoglobin
70% is in the form of the bicarbonate ion (HCO3-)
Carbonic acid and bicarbonate ion work together as a buffer system to resists changes in pH

52. Hypoventilation Respiratory acidosis results
Slow & shallow respiration
Not adequate expiration so
CO2 is not vented out of the body
Production of excess acid
H2O + CO2 = H2CO3 (carbonic acid)
Respiratory acidosis results

53. Hyperventilation Respiratory alkalosis results
Deep & rapid respiration
Too much CO2 is vented out of the body
Not enough acid production
H2O + CO2 = H2CO3 (carbonic acid)
Respiratory alkalosis results
Treatment: trap the CO2 and rebreathe it till breathing returns to normal

54. Imbalances
Pages of handout

55. Chronic Bronchitis
Symptoms: inflammation of mucosa – chronic mucus production
Impairs ventilation and gas exchange
Reduction of airway diameter
“blue bloater” – hypoxia leads to cyanosis – CO2 retention leads to hyperinflation of chest wall
Causative factors: cigarette smoking

56. Normal
Bronchitis

57. Obstructive Emphysema
“pink puffer”
Gas exchange adequate until end stage so stay oxygenated and pink
Breathing is very labored due to lack of alveolar recoil
Barrel chest from hyperinflation of lungs
Alveolar walls collapse = loss of surface area
Causative factor: cigarette smoking

58. 4 features in common Both emphysema and chronic bronchitis have:
Smoking history
Dyspnea = air hunger due to disfunctional breathing
Apnea = no breathing
Eupnea = normal breathing
Coughing & pulmonary infections
Will develop respiratory failure, hypoxia, acidosis

59. Lung Cancer
Basic Info
1/3 of all cancer deaths are due to lung cancers
90% have a smoking history
Metastasizes very rapidly due to vascularity of lungs

60. 3 types
Know the descriptions of these 3 types of lung cancers from your handout
Squamous cell carcinoma
Adenocarcinoma
Oat cell (small cell) carcinoma

61. Squamous cell carcinoma

62. Adenocarcinoma

63. Oat cell carcinoma

64. Treatments Resection of diseased portion of lung Radiation therapy
Chemotherapy

65. Lung Resection

66. Developmental Aspects

67. READ your handout
Read through the Developmental Aspects section of your notes and your handout
Know the related clinical terms on the back page of your handout

68. STUDY