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2013-10-29 03:24:22

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  1. non-respiratory functions of respiratory system
    • water loss and heat elimination
    • enhances lymph flow and venous return
    • helps maintain normal acid-base balance
    • enables speech, singing and other vocalizations
    • defends against foreign matter
    • removes, modifies, activate, or inactivates various materials passing through the pulmonary circulation
    • nose: organ of smell
    • helps expel abdominal contents during urination, defecation, and childbearth
  2. 3 meanings of respiration
    • ventilation of the lungs ( breathing, pulmonary and alveolar)
    • the exchange of gases btwn the air and blood and btween blood and tissue fliud
    • the use of oxygen in cellular metabolism
  3. alveoli
    • incoming airs stops at the alveoli
    • millions of thin-walled, microscopic air sacs
    • exchanges gases with the bloodstream through the aveolar wall, and then flows back out
  4. conducting division
    • passages that serve only for airflow
    • no gas exchange
    • nose, pharynx,  larynx, trachea, and major bronchi
  5. respiratory division
    consists of the alveoli and other gas exchange regions
  6. upper resiratory tract
    • in head and neck
    • nose, pharynx and larynx
  7. lower respiratory tract
    • organs of the thorax
    • trachea, bronchi, and lungs
  8. 3 important pressures in ventilation
    • atomostpheric: barometric 760 mmhG
    • intra-aveolar: intrapulmonary
    • intrapleural: intrathoracic
  9. intra-aveolar
    • intrapulmonary
    •  pressure within the alveoli
    • usually the same as atmospheric pressure
  10. intrapleural
    • intrathoracic
    • pressure within the pleural sac
    • the pressure exerted outside the lungs within the thoracic caivity
    • usually less than atomospheric pressure
  11. changes in the intra-alveolar pressure
    • produce flow of air into and out of lungs
    • if pressure is less than atomospheric pressure air will enter the lungs
    • it pressure is greater than atomospheric pressure air exits the lungs
  12. boyles law
    • at constant temperature
    • pressure of of a given quanity of gas is inversely related to its volume
    • quantity and temperature remains constant
  13. boyles law related to lungs
    • lung volume increases, then their internal pressure or intrapulmonary pressure with fall
    • if the pressure falls below atmostpheric pressure that air will move into the lungs
    • if the lung volum decreases, intrapulmunary pressure rises
    • if pressure rises above atmospheric pressure the air moves out of th lungs
  14. inspiration
    • the 2 pleural layers, their cohesive attractive to eachother and their connections to the lungs and their linging of the rib cage cause inspiration
    • when ribs swing upward and outward, the parietal pleura follows
    • the visceral pleura clings to it by the cohsion of water and it follows the parietal pleura
    • it stretches the aveoli within the lungs
    • the entire lung expands along the thoracic cage
    • as the volume increases, its internal pressure drops and air flows in
  15. intrapleural pressure and inspiration
    • slight vacuum exists btwn 2 pleural layers 
    • about -4 mmHg 
    • drops to -6 mmHg during inspiration as the parietal pleura pulls away
    • some of the pressure change transfer to the interior of the lungs 
    • intrapulmonary pressure drops (in alveoli) allows the air to flow into the lungs (less than atmospheric pressure)
  16. charles law
    the given quantity of gas is directly proportional to is absolue pressure
  17. charles law and inspiration
    • on cold day inspiration will increas temp of air
    • it will warm by the time is reaches the alveoli and the thermal expansion with contribute to the inflation of the lungs
  18. quiet breathing
    dimensions of the thoracic cage increases only a few millimeter in each direction
  19. muscles of respiration in inspiration
    active diaphram and external intercostals
  20. expiration
    relaxed and forced breathing
  21. relaxed breathing
    • passive process achieved mainly by the elastic recoil of the thoracic cage
    • recoil compresses the lungs
    • volume of the thoracic cavitiy decreases
    • raise intrapulmonary pressure about + 3 mmHg
    • air flows down the pressure gradient and out of the lungs
    • elastic properties of the lung
  22. forced breathing
    • accessory muscles rais the intrapulmonary pressure as high as +30 mmHg
    • massive amounts of air moves out of the lungs
  23. active respiration
    • active exhalation abdominal compression
    • active inspiration abdominal relaxation
  24. pneumothorax
    • presence of air in pleural caivity
    • thoracic wall is punctured
    • inspiration sucks air through the wound and into the pleural cavity
    • potentail space becomes an air filled cavity
    • loss of negative intrapleural pressure allows the lungs to recoil and collapse
  25. atelectasis
    • collapse of part or all of the lung
    • can also result from an airway obstruction
  26. cell types in alveoli
    • capillary endothelial cells
    • alveoli epithelial cells (type I and II)
    • fibroblasts (surfactant)
    • macrophages
    • mast cells
  27. controll of brochiolar diameter
    • 1. nervous
    • sympathetic: β2 receptors dilate
    • parasympathetic: Ach constricts
    • 2. Humoral
    • histaminend Ach constrict
    • Adrenergic (β agonists) relax
  28. resistance to airflow
    the greater resistance, the slower the flow
  29. 3 factors that influence airway resistance
    • diameter of the bronchioles
    • pulmonary compliance
    • surface tension of the alveoli and distal bronchioles
  30. bronchodilation
    • increases the diameter of a bronchus or bronchiole
    • decrease resistance
    • epinephrine and sympathetic stimulation stimulates bronchodilation 
    • increase air flow
  31. bronchoconstriction
    • decrease the diameter of a bronchus or bronchiole
    • histamine, parasympathetic nerves, cold air, and chemical irritants stimulate bronchoconstriction
    • suffocation from extreme bronchconstriction is brought about by anaphylactic shock and asthma
    • inscrease resistance and decreases the flow
  32. pulmonary compliance
    • the ease with which the lungs can expand
    • the change in lung volume relative to a given pressure change
    • compliance reduced by degenerative lung diseases in which lungs are stiffened by scar tissue
  33. surface tension of the alveoli and distal bronchioles
    • surfactant: reduces surfaces tensions of water
    • infant respiratory distress syndrome (IRDS) premature babies
  34. elastic recoli
    • lung compliance
    • how readily the lungs rebound after stretch
    • responsible for lungs returning to their preinspiratory volume when inspiratory muscles relax at the end of inspirationo
    • depends on 2 factors: 1. high elastic connective tissue in the lungs 2. alveolar surface tesion
  35. alveolar surface tension
    • thin liquid film lines each alveolus
    • thin film of water is needed for gas exchange
    • reduces tendency of alveoli to recoil
    • helps maintain lung stability 
    • if too much tension will collapse the alveoli
    • prevented by surfactant
  36. pulmonary surfactant
    • produces by the great alveolar cells
    • decreases surface  by disrupting H bonding in water
  37. infant respiratory distress syndrome
    • premature infants that that lack surfactant
    • great difficulty breathing
    • treated with artificial surfacnt until lungs can produce their ow
  38. alveolar ventilation
    only air that enters the alveoli is available for ga exchange
  39. anatomic dead space
    • conducting division of the airway where there is not gas exhange
    • can be alertered somewhat by sympathetic and parasumpathetic stimulation
  40. pulmonary disease
    some aveoli may be unable to exchange gases bc they lack blood flow or their respiratory membrane has been thicked by edema or fibrosis
  41. if a person inhales 500 ml of air
    • 150 stays in anamical dead space
    • 350 mL reaches the aveoli
  42. AVR: alveolar ventilation rate
    • air that ventilates alveoli, respiratory rate
    • relavent to the body's ability to get oxygen to the tissues and dispose of carbon dioxide
  43. lung volumes and capacities
    can be measure by spirometer
  44. spirogram
    graph that records inspiration and expiration
  45. spirometer
    a devicethat recaptures expired breath and records such variables such as rate and depth of breathing, speed of expiration and rate of 02 consumpion
  46. tidal volume
    • volume of air inhaled and exhaled in one cycle of quiet breathing
    • average - 500 mL
  47. inspiratory reserve volume
    • air in excess of tidal volume that can be inhaled with maximum effore
    • IRV
    • average - 3000 mL
  48. expiratory reserve volume
    • air in excess of tidal volume that can be exhaled with max effort
    • ERV
    • average about 1000 mL
  49. residual volume
    • air remaining in the lungs after maximum expiration
    • RV
    • average about 1200 mL
  50. vital capacity
    • total amount of air that can be inhaled and then exhaled with max effort
    • VC = ERV + TV + IRV
    • important measure in pulmonary health
    • average about 4500 mL
  51. inspiratory capacity
    • max amount of air that can be inhaled after a normal tidal expiration
    • IC = TV + IRV
    • about 3500 mL
  52. functional residual capacity
    • amount of air remaining in lungs after normal tidal expiration
    • FRC = R + ERV
    • average about 2200 mL
  53. total lung capacity
    • max amount of air that the lungs can contain
    • TLC = RV + VC
    • average about 5700 mL
  54. forced expiratory volume
    • FEV
    • percentagof vital capacity that can be exhaled in a given time interval
    • healthy adult range: 75-85% in 1 sec
  55. peak flow
    • max speed of expiration
    • blowing into a handheld meter
  56. minute respiratory volume
    • MRV
    • amount of air inhaled per minute
    • TV x respiratory rate
  57. maximum voluntary ventilation
    MVV = MRV during heavy exercise
  58. restrictive disorders
    • reduce pulmonary compliance
    • limit amount that the lungs can be inflated
    • any disease that produces pulmonary fibrosis
    • black-lung, tuberculosis
  59. obstructive distorders
    • disorders that interfere with airflow by narrowing or blocking the airway
    • make it harder to inhale and exhale a given amount of air
    • asthma, chronic bronchitis
  60. emphysema
    combines both elements fo restricive and obstructive disorders
  61. conditions affecting respiratory fucntion
    • diseases affecting diffusion of 02 and co2 across pulmonary membranes
    • reduced ventilation due to mechanical failure
    • inadequate pulmonary blood flow
    • ventilation/ perfusion abnormalities involving a poor matching of air and blood so the efficient gas exchange does not occure
  62. eupnea
    • relaxed quiet breathing 
    • tidal volume of 500 mL and the respiratory rate of 12 - 15 bpm
  63. apnea
    temporary cessation of breathing
  64. dyspnea
    • labored, gasping breathing
    • shortness of breath
  65. hyperpnea
    increased rate and depth of breathing in response to exercise, ain or other conditions
  66. hyperventolation
    increase pulmonary ventilation in excess of metabolic demand
  67. hypoventilation
    reduced pulmonary ventilation
  68. kussmual respiration
    deep, rapid breathing often induced by acidosis
  69. orthopnea
    dyspnea that occure when a person is laying down
  70. respiratory arrest
    permanent cessation of breathing
  71. tachyphnea
    accelerated respiration
  72. systemic gas exchange
    the unloading of 02 and loading of co2 at systemic capillaries
  73. co2 loading
    • co2 diffuses into blood
    • carbonic anhydrace in RBC catalyzed 
    • Co2 + H20 > H2CO3 > HCO 3 - + H+
    • chloride shift: keeps reaction proceeding exhanges HCO3- for Cl- 
    • H+ bings to hemoglobin
  74. O2 unloading
    • H+ bings to HbO2 reduces affinity for 02
    • tends to make hb release o2
    • Hbo2 arrives at systemic capillaries 97% and leaves 75% saturated
    • utilization coefficient: given up 22% of its o2 load
  75. venous reserve
    o2 remaining in the blood after it passes thorugh the capillary beds
  76. Co2 unloading
    • as Hb loads 02 affinity for H= decreases , H+ dissociates from Hb and binds with HCO3+
    • reverse rxn: co2 + h20 < h2CO3 < hco3 - + H+
    • reverse chloride shift: Hco3- diffuses ack into RBC in exchange for Cl-, free co2 generated diffuses into alveolus to be exhaled
  77. carbon monoxide
    • CO 
    • competes for o2 binding sites on Hb molecule
    • colorless, odorless gas in cigarette smoke, engine exhaust fumes from furances and space heaters
  78. carboxyhemoglobin
    • CO bings to ferrous ion of hb
    • bings 210x tightly as o2
    • ties ub hb for a long time
    • non-smokers: less than 1.5% hb occupied by CO
    • smokers: 10%
    • atmospheric concentrations of 0.2% CO is quickly lethal
  79. rate and depth of breathing adjust to main levels of
    • pH : 7.35- 7.45
    • Pco2: 40 mmHg
    • Po2: 95 mmHg
  80. brainstem respiratory centers
    recieve iput form the central and peripheral chemoreceptors that monitor the composition of blood and CSF
  81. most potent stimulus for breathing
    pH, then Co2 then O2
  82. maintain pH in the brain
    • pulmonary ventilation is adjusted
    • central chemoreceptors in the medulla oblongata produce about 75% change in respiration induced by pH shift
    • H+ does not cross BBB easily
    • CO2 does and is CSF reeacts with water and produces carbonic acid, it will dissociate into bicarbonate and hydrogen ions
    • most H+ remains free and greatly stimulates the central chemoreceptors
  83. peripherial chemoreceptors
    • H+ ions potent stimulus
    • will product 25% of the respiratory response to pH change
  84. respiratory acidosis and alkalosis
    pH imbalances resulting from a mismatch between the rate of pulmonary ventilation and the rate of co2 prodcution
  85. hyperventilation is correctic homeostatic
    • in response to acidosis
    • "blowing off" Co2 faster that the body produces
    • it pushes rxn to the ledtreduces H+,
    • reduce acid and raise blood pH towards normal
  86. hypoventilation is a corrective homeostatic
    • respsonse to alkalsis
    • allows co2 to accumlate in body fluids faster that we exhale it
    • shift rxn to the right
    • raisin H+ concentration and lowering pH to normal
  87. ketoacidosis
    • acidosis brought about by rapid fat oxidation releasing acid ketone bodies
    • diabetes mellitus
    • insuces Kussmaul respiration
    • hyperventilation cannot remove ketone bodies 
    • but blowing off co2 can reduce the co2 concentration and can compensate for the ketone bodies to some degress
  88. carbon dioxide indirect effects on respiration
  89. direct effects of CO2 on respiration
    • increase of co2 at begining of exercise directly stimulates peripheral chemoreceptors
    • triggers and increase in ventilation more quickly than central chemoreceptors
  90. effects of O2 on respiraton
    • Po2 usually has little effect on respiration
    • chronic hypoxemia ( po2 < 60 mmHg) can significantly stimulate ventilation
  91. hypoxic drive
    • respiration driven more by low Po2 thatn CO2 or pH
    • emphysema and pnueumonia
    • high elevations after several days
  92. hypoxia
    • a deficiency of 02 in the tissue or the inabilitto use o2
    • consequence of respiratory disease
  93. hypoxemic hypoxia
    • state of low arterial Po2
    • usually due to inadequate pulmonary gas exchange
    • o2 deficiency at high elevations, impaired ventilation
    • drowning, aspiration of a foreign body, respiratory arrest, degenerative lung diseaese
  94. ischemic hypoxia
    • inadequate circulation of blood
    • CHF
  95. anemic hypoxia
    due to anemia resulting from the inability of blood to carry adequat o2
  96. histotoxic hypoxia
    metabolic poisons such as cyanide that prevent the tissues from using o2 delivered to them
  97. cyanosis
    • blueness of the skin
    • sign of hypoxia
  98. oxygen toxicity
    • pure o2 breath at 2.5 atm or greater
    • safe to breath 100% oxygen at 1 atm for a few hours
    • generates free radicals of H2O2
    • destroys enzymes
    • damages nerous tissue
    • leads to seizures, coma, and death
  99. hyperbaric oxygen
    • formly used to treat premature infants
    • causes retinal damage
  100. COPD
    • chronic obstructive pulmonary disease
    • refers to any disorder in which there is a long-term obstruction of airflow and substantial reduction of pulmary ventilation
    • chronic bronchitis
    • emphysema
    • usually associated with smoking
    • other risk factors are air pollution or occupation exposure to airbone irritants
  101. chronic bronchitis
    • COPD
    • inflammation and hyper plasis of bronchial mucosa
    • cilia immobilized and reduced in number
    • goblet cells enlarge and produce excess mucus
    • develop chronic cough to bring up extra mucus with less cilia to move it up
    • sputum formed (mucus and cellular debris): ideal growth media for bateria, incapacitates alveolar macrophages
    • leads to chronic infection and bronchial inflammation
    • symptoms: dyspnea, hypoxia, cynosis, and attack of coughing
  102. emphysema
    • COPD
    • aveolar walls break down
    • lung has larger but fewer alveoli
    • much less respiratory membrane for gas exchange
    • lungs fibrotic and less elastic
    • healthly lungs are like a sponge, emphysema lungs are more like a rigid ballon
    • air passages collapse and obstructs outflow of air and air is trapped in lungs
    • weaken thoracic muscles, spend 3 - 4x times about of energy just to breathe
  103. pulmonary artery
    supply blood capillaries that surround the aveolus
  104. respiratory membrane
    • the barrier btwn the alveolar air and the blood
    • consists of: squamous alveolar cells, endothelial cells of blood capillary, their shared basement membrane
    • important to prevent fluid accumulating in alveoli
    • gases diffuse too slowly through liquid to sufficiently aerate the blood
    • alveoli are kept dry by absorption of excess liquid by the blood capillaries
    • lungs has more extensive lymphatic drainage
    • low capillary bp prevents rupture of the delicate respiratory membrane
  105. composition of air
    • nitrogen: 78.6%
    • oxygen: 20.9%
    • Co2: 0.04% 
    • water vapor: 0-4% depending on temp and humidity
    • minor gases: argon, neon, helium, meathane and ozne
  106. daltons law
    • the total atmospheric pressure is the sum of the contributions of the individl gases
    • at sea level 1 atm = 760 mmHG
  107. composition of inspired air and alveolar air is different bc
    • air humidifies by contact with the mucous membrane: alveolar Ph20 is more than 10x greated than inhaled air
    • freshly inspired air mixes with residual air left from the previous respiratory cycle: oxygen is diluted and enriched with c02
    • alveolar air exhanges o2 and co2 with blood: po2 of alveolar is about 65% that of inspired air and pCO2 is more than 130x higher
  108. alveolar gas exchange
    • the back and forth traffic of o2 and co2 across the respiratory membrane
    • air in the alveolus is in contact with a film of water covering the alveolar epithelium
    • for o2 to get int the blood it must dissolve in water
    • pass through the respiratory membrane seperating the air from the blood stream
    • for co2 to leave the blood it must pass the other way and diffuse out of the water into the alvolar air 
    • gases diffused down their own concentration gradient until the ppof each gas in the air is equal to the pp in water
  109. henrys law
    • at air-water interface, for a given temp, the amout of gas that dissolves in water is determined by its solubility in water and its pp in the air
    • the greater the po2 in alveolar air, the more o2 blood picks up
    • since blood arriving at an alveolus has a high pco2 than air, it releases co2 into the  air
    • at alveolus blood unloads co2 and loads o2 which involces erthrocytes
    • efficiency depends on how long RBC stays in alveolar capillaries 0.25 sec to reach equilidrium, at rest RBC spend.75 sec, strenous exercise .3 secs
    • each gas in a mixture behaves independently
    • one gas DOES NOT influence the diffusion of another
  110. pressure gradient of the gases
    • po2: 104 mmHg in alveolar air and 40 mmhg in blood
    • Pco2: 46 mmHg in blood ariving and 40 mmHg in alvelar air
  111. hyperbaric o2 therapyse
    • treatment with o2 greater than one atm pressure
    • gradient differences are more, more o2 diffuse to blood
    • treats gangrene and co posioning
  112. high altitudes
    • the pp of gases are lower
    • gradient difference is less
    • less o2 diffuses into blood
  113. solubility of gases
    • CO2 is 20x more soluble as 02
    • equal amounts of o2 and co2 are exchanged across the respiratory membrane bc co2 is much more soluble is diffuses more rapidly
    • o2 twice as soluble as n2
  114. membrane thickness
    • 0.5μm thick
    • little obstcale for diffusion
    • pulmonary edeman in the left side of the ventricular failure causes edema and thickening of the respiratory membrane
    • pneumonia causes thickening of respiratory membrane
    • thicker mebrame: farther travel btwn blood and air and cannot equilibrate fast enought to keep up with blood flow
  115. membrane SA
    • 100 mL blood in alveolar capillaries spread thingly over 70 m2
    • emphysema, lung cance, and tb decrease SA for gas exchange
  116. ventilation-perfusin coupling
    • ability to match ventilation and perfusion
    • gas exchange requires both good ventilation of alveolus and good perfusion of the capillaries
    • at rest ratio 0.8: flow of 4.2 L air and 5.5 L of blood per minute
  117. pulmonary edema
    • caused by left heart failure and damage to pulmonary membrane
    • safety factor: negative interstitial pressure, lumphatic pumping,and decreases interstitial osmotic pressure
  118. gas transport
    process of carrying gases from the aveoli to the systemic tissues and vice versa
  119. o2 transport
    • 98.5% bound to hb
    • 1.5% dissolved in plasma
    • arterial blood carries about 20 mL of o2 per deciliter
  120. co2 transport
    • 60% as bicarbonate ion
    • 30% boung to hb
    • 10% dissolved in plasma
  121. oxyhemoglobin
    • hbo2 o2 bound to hemoglobin
    • 100% saturated with 4 o2 molecules
    • 50% saturated with 2 o2 molecules
  122. deoxyhemoglobin
    • HHB 
    • no o2