ch 22

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Author:
swasdo
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277003
Filename:
ch 22
Updated:
2014-06-16 22:09:14
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bio242
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respiratory system
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  1. major function of the respiratory system
    • supply body with O2 for cellular respiration; dispose of CO2, a waste product of cellular respiration
    • its four processes involve both respiratory and circulatory systems
    • also functions in olfaction and speech
  2. pulmonary ventilation
    • breathing
    • movement of air into and out of lungs
  3. external respiration
    O2 and CO2 exchange between lungs and blood
  4. transport
    O2 and CO2 in blood
  5. internal respiration
    O2 and CO2 exchange between systemic blood vessels and tissues
  6. what are the major organs of the respiratory system
    • nose, nasal cavity, paranasal sinuses
    • pharynx
    • larynx
    • trachea
    • bronchi and their branches
    • lungs and alveoli
  7. respiratory zone
    • site of gas exchange
    • microscopic structures- respiratory bronchioles, alveolar ducts, and alveoli
  8. conducting zone
    • conduits to gas exchange sites
    • incudes all other respiratory structures; cleanses, warms, and humidifies air
  9. functions of the nose
    • provides an airway for respiration
    • moistens and warms entering air
    • filters and cleans inspired air
    • serves as resonating chamber for speech
    • houses olfactory receptors
  10. nasal cavity respiratory mucosa
    • pseudostratified ciliated columnar epithelium
    • mucous and serous secretions contain lysozyme and defensins
    • cilia move contaminated mucus posteriorly to throat
    • inspired air warmed by plexuses of capillaries and veins
    • sensory nerve endings trigger sneezing
  11. functions of nasal mucosa and conchae
    • filter heat and moisten air during inhalation
    • during exhalation they reclaim heat and moisture
  12. pharynx
    • muscular tube that connects nasal cavity and mouth to larynx and esophagus, composed of skeletal muscle
    • three regions: nasopharynx, oropharynx, laryngopharynx
  13. nasopharynx
    • air passageway posteiror to nasal cavity
    • lining: pseudostratified columnar epithelium
    • soft palate and uvula close nasopharynx during swallowing
  14. laryngopharynx
    • passageway for food and air
    • posterior to upright epiglottis
    • extends to larynx, where continuous with esophagus
    • lined with stratified squamous epithelium
  15. larynx
    • attaches to hyoid bone; opens into laryngopharynx; continous with trachea
    • functions are to provide patent airway, routes air and food into proper channels, voice production
  16. what houses the vocal folds
    larynx
  17. vocal ligaments
    • deep to aryngeal mucosa
    • contain elastic fibers
    • form core of vocal folds.
    • glottis-opening between vocal folds
    • folds vibrate to produce sound as air rushes up from lungs
  18. vestibular folds
    • false vocal cords
    • superior to vocal folds
    • no part in sound production
    • help to close glottis during swallowing
  19. epithelium of larynx
    • suerior portion stratified squamous epithelium
    • inferior to vocal folds- pseudostratified ciliated columnar epithelium
  20. valsalva's maneuver
    • glottis closes to prevent exhalation
    • abdominal muscles contract
    • intra-abdominal pressure rises
    • helps to empty rectum or stabilizes trunk during heavy lifting
  21. trachea
    • windpep from larynx to mediastnum
    • wall composed of three layers: mucosa, submucosa, adventitia
  22. mucosa of the trachea
    ciliated pseudostratified epithelium with goblet cells
  23. submucosa
    connective tissue with seromucous glands
  24. adventitia of trachea
    outermost layer made of connective tissue, encases C shaped rings of hyaline cartilage
  25. trachealis muscle
    • connects posterior parts of cartilage rings
    • contracts during coughing to expel mucus
  26. carina
    • spar of cartilage on last, expanded tracheal cartilage
    • point where trachea branches into two main bronchi
  27. each main bronchus branches into lobar bronchi.. how many on right and how many on left
    three on right, two on left
  28. list in order from big to small: bronchioles, terminal bronchioles, bronchi
    bronchi, bronchioles, terminal bronchioles
  29. respiratory zone
    beings as terminal bronchioles > respiratory bronchioles > alveolar ducts > alveolar sacs
  30. how many alveoli make up most of lung volume
    300 million alveoli
  31. what are alveolar walls made of
    single layer squamous epithelium
  32. alveolar pores
    • connect adjavent aleoli
    • equalize air pressure throughout lung
  33. alveolar macrophages
    • keep alveolar surfaces sterile
    • 2 million dead macrophages/hour carried by cilia > throat > swallowed
  34. lungs
    • occupy all thoracic cavity except mediastinum
    • rott: site of vascular and bronchial attachment to mediastinum
    • costal surface: anterior, lateral, and posterior surfaces
    • composed primarily of alveoli
    • balance-stroma elastic connective tissue > elasticity
  35. apex of the lung
    superior tip; deep to clavicle
  36. base of lung
    inferior surface; rests on diaphragm
  37. hilum
    on mediastinal surface; site for entry/exit of blood vessels, bronchi, lymphatic vessels, and nerves
  38. which lung is smaller
    the left is smaller than the right
  39. bronchopulmonary segments
    • separated by connective tissue septa.
    • if diseased can be individually removed
  40. lobules
    • smallest subdivisions visible to naked eye
    • served by bronchioles and their branches
  41. pulmonary circulation
    • low pressure, high volume
    • pulmonary arteries deliver systemic venous blood to lungs to oxygenation (branch profusely, feed into pulmonary capillary networks)
    • pulmonary veins carry oxygenated blood from respiratory zones to heart
  42. bronchial arteries
    • provide oxygenated blood to lung tissue
    • arise from aorta and enter lungs at hilum
    • part of systemic circulation (high pressure, low volume)
    • supply all lung tissue except alveoli
    • bronchial veins anastomose with pulmonary veins
  43. pleurae
    • thin, double layered seorsa, divids thoracic cavity into two pleral compartments and mediastinum
    • parietal pleura: on thoracic wall, superior face of diaphragm, around heart, between lungs
    • visceral pleura: on external lung surface
    • pleural fluid: fills slitlike pleural cavity. provides lubrication and surface tension and assists with expansion and recoil
  44. inspiration
    gases flow into lungs
  45. expiration
    gases exit lungs
  46. atmospheric pressure
    • pressure exerted by air surround body
    • 760 mm Hg at sea level= 1 atmosphere
  47. negative respiratory pressure means
    less than atmospheric pressure
  48. positive respiratory pressure means
    greater than atmospheric pressure
  49. zero respiratory pressure means
    equals atmospheric pressure
  50. intrapulmonary pressure
    • pressure in alveoli
    • fluctuates with breathing
    • always eventually equalizes with atmospheric pressure
  51. intrapleural pressure
    • pressure in pleural cavity
    • fluctuates with breathing
    • always a negative pressure
    • fluid level must be minimal, pumped out by lymphatics, if acumulates, positive pressure> lung collapses
  52. sequence of events for inspiration
    • 1. inspiratory muscles contract; diaphragm descends, rib cage rises
    • 2. thoracic cavity colume increases
    • 3. lungs are stretched; intrapulmonary volume increases
    • 4. intrapulmonary pressure drops to -1 mm Hg
    • 5. air flows into lungs down its pressure gradient until intrapulmonary pressure is 0
  53. sequence of events for expiration
    • 1. inspiratory muscles relax, diaphragm rises, rib cage descends due to recoild of costal cartilages
    • 2. thoracic cavity volume decreases
    • 3. elastic lungs recoil passively; intrapulmonary volume decreases
    • 4. intrapulmonary pressure rises to +1 mm Hg
    • 5. air flow out of the lungs down its pressure gradient until intrapulmonary pressure is 0
  54. what are the three factors that hinder air passage and pulmonary ventilation and require energy to overcome
    • airway resistance
    • alveolar surface tension
    • lung compliance
  55. what hormone decreases air resistance
    epinephrine
  56. surface tension
    • attracts liquid molecules to one another at gas liquid interface
    • resists any force that tends to increase surface area of liquid
    • water- high surface tension; coats alveolar walls > reduces them to smallest size
  57. surfactant
    • detergent like lipid and protein complex produced by type II alveolar cells
    • reduces surface tension of alveolar fluid and discourages alveolar collapse
    • insufficient quantity in premature infants causes infant respiratory distress syndrome
  58. lung compliance is diminished by
    • nonelastic scar tissue replacing lung tissue
    • reduced production of surfactant
    • decreased flexibility of thoracic cage
  59. homeostatic imbalances that reduce compliance
    • deformiities of thorax
    • ossification of costal cartilage
    • paralysis of intercostal muscles
  60. tidal volume
    amount of air inhaled or exhaled with each breath under resting conditions
  61. inspiratory reserve volume
    amount of air that can be forcefully inhaled after a normal tidal volume inspiration
  62. expiratory reserve volume
    amount of air that can be forcefully exhaled after a normal tidal volume expiration
  63. residual volume
    amount of air remaining in the lungs after a forced expiration
  64. total lung capacity
    maximum amount of air contained in lugns after a maximum inspiratoyr effort
  65. vital capacity
    maximum amount of air that an be expired after a maximum inspiratory effort
  66. inspiratory capacity
    maximum amount of air that can be inspired after a normal tidal volume expiration
  67. functional residual capacity
    volume of air remaining in the lungs after a normal tidal volume expiration
  68. anatomical dead space
    • no contribution to gas exchange
    • air remaining in passageways
  69. alveolar dead space
    nonfunctional alveoli due to collapse or obstruction
  70. total dead space
    sum of anatomical and alveolar dead space
  71. spirometer
    • instrument for measuring respiratory volumes and capacities
    • spirometry can distinguish between obstructive pulmonary disease and restrictive disorders
  72. minute ventilation
    • total amount of gas flow into or out of respiratory tract in one minute
    • norm=6 L/min
  73. external respiration
    diffusion of gases in lungs
  74. internal respiration
    diffusion of gases at body tissues
  75. partial pressure
    • pressure exerted by each gas in mixture
    • directly proportional to its percentage in mixture
  76. composition of alveolar gas
    • alveoli contain more CO2 and water vapor than atmospheric air
    • gas exchanges in lungs
    • humidification of air
    • mixing of alveolar gas with each breath
  77. external respiration
    • exchange of O2 and CO2 across respiratory membrane
    • influenced by thickness, and surface area of respiratory membrane
    • partial pressure gradients and gas solubilities
    • ventilation and perfusion coupling
  78. respiratory membranes
    .5-1 m thick
  79. perfusion
    blood flow reaching alveoli
  80. ventilation
    amount of gas reaching alveoli
  81. most of CO2 is transported as
    bicarbonate ions
  82. neural controls of respiration
    • neurons in reticular formation of medulla and pons
    • clustered neurons in medulla important
    • *ventral and dorsal respiratory group
  83. ventral respiratory group
    • rhythm generating and integrative center
    • sets eupnea (12-15 breaths/min)
    • its inspiratory neurons excite inspiratory muscles via phrenic and intercostal nerves
    • expiratory neurons inhibit inspiratory neurons
  84. dorsal respiratory group
    • near root of carnial nerve IX
    • integreates input from pirpheral stretch and chemoreceptors; sends info
  85. pontine respiratory centers
    • influence and modify activity of VRG
    • smooth out transition between inspiration and expiration and vice versa
    • transmit impulses to VRG > modify and fine tune breathing rhythms during vocalization, sleep, exercise
  86. generation of respiratory rhythm
    • not well understood
    • one hypothesis: pacemaker┬áneurons with intrinsic rhythmicity
    • widely accepted hypothesis: reciprocal inhibition of two sets of interconnected pacemaker neurons in medulla that generate rhythm
  87. hyperventilation
    increased depth and rate of breathing that exceeds body's need to remove CO2
  88. apnea
    breathing cessation from abnormally low Pco2
  89. what is the most powerful respiratory stimulant
    rising CO2 levels
  90. hypothalamic controls
    act through limbic system to modify rate and depth of respiration
  91. cortical controls
    direct signals from cerebral motor cortex that bypass medullary controls
  92. hyperpnea
    increased ventilation in response to metabolic needs
  93. acclimatization
    • respiratory and hematopoietic adjustments to long term move to high altitude
    • chemoreceptors become more responsive to Pco2 when Po2 declines
    • substantial decline in Po2 directly stimulates peripheral chemoreceptors
    • result minute ventilation increases and stabilizes in few days to 2-3 l/min higher than at sea level

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