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  • 1. Chapter 23: The Respiratory System Biol 141 A & P
  • 2. The Respiratory System
    • Cells produce energy:
      • for maintenance, growth, defense, and division
      • through mechanisms that use oxygen and produce carbon dioxide
  • 3. Oxygen
    • Is obtained from the air by diffusion across delicate exchange surfaces of lungs
    • Is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs
    3D Movie of Respiratory System PLAY
  • 4. 5 Functions of the Respiratory System
    • Provides extensive gas exchange surface area between air and circulating blood
    • Moves air to and from exchange surfaces of lungs
    • Protects respiratory surfaces from outside environment
    • Produces sounds
    • Participates in olfactory sense
  • 5. Components of the Respiratory System Figure 23–1 3D Peel-Away of Respiratory System PLAY
  • 6. Organization of the Respiratory System
    • The respiratory system is divided into the upper respiratory system , above the larynx, and the lower respiratory system , from the larynx down
  • 7. The Respiratory Tract
    • Consists of a conducting portion :
      • from nasal cavity to terminal bronchioles
    • Consists of a respiratory portion :
      • the respiratory bronchioles and alveoli
      • Alveoli
    • Are air-filled pockets within the lungs
      • where all gas exchange takes place
    The Respiratory Tract PLAY
  • 8. The Respiratory Epithelium Figure 23–2
  • 9. The Respiratory Epithelium
    • For gases to exchange efficiently:
      • alveoli walls must be very thin (< 1 µ m)
      • surface area must be very great (about 35 times the surface area of the body)
  • 10. The Respiratory Mucosa
    • Consists of:
      • an epithelial layer
      • an areolar layer
    • Lines conducting portion of respiratory system
  • 11. The Lamina Propria
    • Underlies areolar tissue
    • In the upper respiratory system, trachea, and bronchi:
      • contains mucous glands that secrete onto epithelial surface
    • In the conducting portion of lower respiratory system:
      • contains smooth muscle cells that encircle lumen of bronchioles
  • 12. Structure of Respiratory Epithelium
    • Changes along respiratory tract
    • Alveolar Epithelium
    • Is a very delicate, simple squamous epithelium
    • Contains scattered and specialized cells
    • Lines exchange surfaces of alveoli
  • 13. How are delicate respiratory exchange surfaces protected from pathogens, debris, and other hazards?
  • 14. The Respiratory Defense System
    • Consists of a series of filtration mechanisms
    • Removes particles and pathogens
    • * Components of the Respiratory Defense System
    • Goblet cells and mucous glands : produce mucus that bathes exposed surfaces
    • Cilia : sweep debris trapped in mucus toward the pharynx ( mucus escalator )
    • Filtration in nasal cavity removes large particles
    • Alveolar macrophages engulf small particles that reach lungs
  • 15. The Upper Respiratory System Figure 23–3
  • 16. The Nose
    • Air enters the respiratory system:
      • through nostrils or external nares
      • into nasal vestibule
    • Nasal hairs :
      • are in nasal vestibule
      • are the first particle filtration system
  • 17. The Nasal Cavity
    • The nasal septum :
      • divides nasal cavity into left and right
    • Mucous secretions from paranasal sinus and tears:
      • clean and moisten the nasal cavity
    • Superior portion of nasal cavity is the olfactory region :
      • provides sense of smell
  • 18. Air Flow
    • From vestibule to internal nares :
      • through superior , middle, and inferior meatuses
      • Meatuses
    • Constricted passageways that produce air turbulence:
      • warm and humidify incoming air
      • trap particles
  • 19. The Palates
    • Hard palate :
      • forms floor of nasal cavity
      • separates nasal and oral cavities
    • Soft palate :
      • extends posterior to hard palate
      • divides superior nasopharynx from lower pharynx
  • 20. Air Flow
    • Nasal cavity opens into nasopharynx through internal nares
    • The Nasal Mucosa
    • Warm and humidify inhaled air for arrival at lower respiratory organs
    • Breathing through mouth bypasses this important step
  • 21. The Pharynx and Divisions
    • A chamber shared by digestive and respiratory systems
    • Extends from internal nares to entrances to larynx and esophagus
    • Nasopharynx
    • Oropharynx
    • Laryngopharynx
  • 22. The Nasopharynx
    • Superior portion of the pharynx
    • Contains pharyngeal tonsils and openings to left and right auditory tubes
    • The Oropharynx
    • Middle portion of the pharynx
    • Communicates with oral cavity
    • The Laryngopharynx
    • Inferior portion of the pharynx
    • Extends from hyoid bone to entrance to larynx and esophagus
  • 23. What is the structure of the larynx and its role in normal breathing and production of sound?
  • 24. Anatomy of the Larynx Figure 23–4
    • Air Flow-
    • From the pharynx enters the larynx :
      • a cartilaginous structure that surrounds the glottis
  • 25. Cartilages of the Larynx
    • 3 large, unpaired cartilages form the larynx :
      • the thyroid cartilage
      • the cricoid cartilage
      • the epiglottis
  • 26. The Thyroid Cartilage
    • Also called the Adam’s apple
    • Is a hyaline cartilage
    • Forms anterior and lateral walls of larynx
    • Ligaments attach to hyoid bone, epiglottis, and laryngeal cartilages
  • 27. The Cricoid Cartilage
    • Is a hyaline cartilage
    • Form posterior portion of larynx
    • Ligaments attach to first tracheal cartilage
    • Articulates with arytenoid cartilages
    • The Epiglottis
    • Composed of elastic cartilage
    • Ligaments attach to thyroid cartilage and hyoid bone
  • 28. Cartilage Functions
    • Thyroid and cricoid cartilages support and protect:
      • the glottis
      • the entrance to trachea
    • During swallowing:
      • the larynx is elevated
      • the epiglottis folds back over glottis
    • Prevents entry of food and liquids into respiratory tract
  • 29. The Glottis Figure 23–5
    • 3 pairs of Small Hyaline Cartilages of the Larynx
    • arytenoid cartilages, corniculate cartilages
      • cuneiform cartilages
  • 30. Cartilage Functions
    • Corniculate and arytenoid cartilages function in:
      • opening and closing of glottis
      • production of sound
  • 31. Ligaments of the Larynx
    • Vestibular ligaments and vocal ligaments :
      • extend between thyroid cartilage and arytenoid cartilages
      • are covered by folds of laryngeal epithelium that project into glottis
      • 1) The Vestibular Ligaments
    • Lie within vestibular folds :
      • which protect delicate vocal folds
  • 32. Sound Production
    • Air passing through glottis:
      • vibrates vocal folds
      • produces sound waves
      • Sound Variation
    • Sound is varied by:
      • tension on vocal folds: slender and short =high pitched, thicker and longer = low pitched
      • voluntary muscles (position arytenoid cartilage relative to thyroid cartilage)
  • 33. Speech
    • Is produced by:
      • phonation :
        • sound production at the larynx
      • articulation :
        • modification of sound by other structures
  • 34. The Laryngeal Musculature
    • The larynx is associated with:
      • muscles of neck and pharynx
      • intrinsic muscles that:
        • control vocal folds
        • open and close glottis
        • Coughing reflex: food or liquids went “down the wrong pipe”
  • 35. Anatomy of the Trachea Figure 23–6 What is the structure of airways outside the lungs?
  • 36. The Trachea
    • Also called the windpipe
    • Extends from the cricoid cartilage into mediastinum
      • where it branches into right and left pulmonary bronchi
      • The Submucosa
      • Beneath mucosa of trachea
    • Contains mucous glands
  • 37. The Tracheal Cartilages
    • 15–20 tracheal cartilages :
      • strengthen and protect airway
      • discontinuous where trachea contacts esophagus
    • Ends of each tracheal cartilage are connected by:
      • an elastic ligament and trachealis muscle
  • 38. The Primary Bronchi
    • Right and left primary bronchi :
      • separated by an internal ridge (the carina )
      • 1) The Right Primary Bronchus
    • Is larger in diameter than the left
    • Descends at a steeper angle
  • 39. Structure of Primary Bronchi
    • Each primary bronchus:
      • travels to a groove ( hilus ) along medial surface of the lung
      • Hilus-
    • Where pulmonary nerves, blood vessels, and lymphatics enter lung
    • Anchored in meshwork of connective tissue
  • 40. The Root of the Lung
    • Complex of connective tissues, nerves, and vessels in hilus:
      • anchored to the mediastinum
  • 41. Gross Anatomy of the Lungs Figure 23–7
    • Left and right lungs :
      • are in left and right pleural cavities
    • The base :
      • inferior portion of each lung rests on superior surface of diaphragm
  • 42. Lobes of the Lungs
    • Lungs have lobes separated by deep fissures
    • 1) The Right Lung- Has 3 lobes:
      • superior, middle, and inferior
      • separated by horizontal and oblique fissures
      • 2) The Left Lung- Has 2 lobes:
      • superior and inferior
      • are separated by an oblique fissure
  • 43. Relationship between Lungs and Heart Figure 23–8
  • 44. Lung Shape
    • Right lung:
      • is wider
      • is displaced upward by liver
    • Left lung:
      • is longer
      • is displaced leftward by the heart forming the cardiac notch
  • 45. The Bronchial Tree
    • Is formed by the primary bronchi and their branches
    • Extrapulmonary Bronchi
    • The left and right bronchi branches outside the lungs
    • Intrapulmonary Bronchi
    • Branches within the lungs
  • 46. Bronchi and Lobules Figure 23–9 A Primary Bronchus Branches to form secondary bronchi (lobar bronchi) 1 secondary bronchus goes to each lobe
  • 47. Secondary Bronchi
    • Branch to form tertiary bronchi , also called the segmental bronchi
    • Each segmental bronchus :
      • supplies air to a single bronchopulmonary segment-
      • The right lung has 10
      • The left lung has 8 or 9
  • 48. Bronchial Structure
    • The walls of primary, secondary, and tertiary bronchi:
      • contain progressively less cartilage and more smooth muscle
      • increasing muscular effects on airway constriction and resistance
  • 49. The Bronchioles Figure 23–10 Bronchitis: Inflammation of bronchial walls: causes constriction and breathing difficulty
  • 50. The Bronchioles
    • Each tertiary bronchus branches into multiple bronchioles
    • Bronchioles branch into terminal bronchioles:
      • 1 tertiary bronchus forms about 6500 terminal bronchioles
  • 51. Bronchiole Structure
    • Bronchioles:
      • have no cartilage
      • are dominated by smooth muscle
      • Autonomic Control
    • Regulates smooth muscle:
      • controls diameter of bronchioles
      • controls airflow and resistance in lungs
  • 52. Bronchodilation
    • Dilation of bronchial airways
    • Caused by sympathetic ANS activation
    • Reduces resistance
    • Bronchoconstriction
    • Constricts bronchi
    • Caused by:
      • parasympathetic ANS activation
      • histamine release (allergic reactions)
  • 53. Asthma
    • Excessive stimulation and bronchoconstriction
    • Stimulation severely restricts airflow
  • 54. Pulmonary Lobules
    • Are the smallest compartments of the lung
    • Are divided by the smallest trabecular partitions ( interlobular septa )
    • Each terminal bronchiole delivers air to a single pulmonary lobule
    • Each pulmonary lobule is supplied by pulmonary arteries and veins
  • 55. Exchange Surfaces
    • Within the lobule:
      • each terminal bronchiole branches to form several respiratory bronchioles , where gas exchange takes place
  • 56. Alveolar Organization Figure 23–11
    • Respiratory bronchioles are connected to alveoli along alveolar ducts
    • Alveolar ducts end at alveolar sacs:
      • common chambers connected to many individual alveoli
  • 57. An Alveolus
    • Has an extensive network of capillaries
    • Is surrounded by elastic fibers
    • Alveolar Epithelium
    • Consists of simple squamous epithelium
    • Consists of thin, delicate Type I cells
    • Patrolled by alveolar macrophages , also called dust cells
    • Contains septal cells ( Type II cells ) that produce Surfactant- an oily secretion which
    • 1) Contains phospholipids and proteins
    • 2) Coats alveolar surfaces and reduces surface tension
  • 58. Respiratory Distress
    • Difficult respiration:
      • due to alveolar collapse
      • caused when septal cells do not produce enough surfactant
  • 59. Respiratory Membrane - The thin membrane of alveoli where gas exchange takes place
    • 3 Parts of the Respiratory Membrane
    • Squamous epithelial lining of alveolus
    • Endothelial cells lining an adjacent capillary
    • Fused basal laminae between alveolar and endothelial cells
    • Diffusion- Across respiratory membrane is very rapid:
      • because distance is small
      • gases (O 2 and CO 2 ) are lipid soluble
  • 60. Inflammation of Lobules
    • Also called pneumonia :
      • causes fluid to leak into alveoli
      • compromises function of respiratory membrane
  • 61. Blood Supply to Respiratory Surfaces
    • Each lobule receives an arteriole and a venule
      • respiratory exchange surfaces receive blood:
        • from arteries of pulmonary circuit
      • a capillary network surrounds each alveolus:
        • as part of the respiratory membrane
      • blood from alveolar capillaries:
        • passes through pulmonary venules and veins
        • returns to left atrium
  • 62. Blood Supply to the Lungs
    • Capillaries supplied by bronchial arteries:
      • provide oxygen and nutrients to tissues of conducting passageways of lung
    • Venous blood bypasses the systemic circuit and flows into pulmonary veins
  • 63. Blood Pressure
    • In pulmonary circuit is low (30 mm Hg)
    • Pulmonary vessels are easily blocked by blood clots, fat, or air bubbles, causing pulmonary embolism
  • 64. Pleural Cavities and Pleural Membranes Figure 23–8
  • 65. Pleural Cavities and Pleural Membranes
    • 2 pleural cavities :
      • are separated by the mediastinum
    • Each pleural cavity:
      • holds a lung
      • is lined with a serous membrane (the pleura )
    • Pleura consist of 2 layers:
      • parietal pleura
      • visceral pleura
    • Pleural fluid :
      • lubricates space between 2 layers
  • 66. Respiration
    • Refers to 2 integrated processes:
      • External respiration- Includes all processes involved in exchanging O 2 and CO 2 with the environment
      • Internal respiration- Also called cellular respiration
    • Involves the uptake of O 2 and production of CO 2 within individual cells
  • 67. 3 Processes of External Respiration
    • Pulmonary ventilation (breathing)
    • Gas diffusion :
      • across membranes and capillaries
    • Transport of O 2 and CO 2 :
      • between alveolar capillaries
      • between capillary beds in other tissues
  • 68. What physical principles govern the movement of air into the lungs?
  • 69. Pulmonary Ventilation
    • Is the physical movement of air in and out of respiratory tract
    • Provides alveolar ventilation
    InterActive Physiology: Respiratory System: Anatomy Review: Respiratory Structures PLAY
  • 70. Gas Pressure and Volume Figure 23–13 Atmospheric Pressure
    • The weight of air:
      • has several important physiological effects
  • 71. Boyle’s Law
    • Defines the relationship between gas pressure and volume:
    • P = 1/V
    • In a contained gas:
      • external pressure forces molecules closer together
      • movement of gas molecules exerts pressure on container
  • 72. Mechanisms of Pulmonary Ventilation Respiration: Pressure Gradients PLAY Figure 23–14
    • Pressure Difference
    • Air flows from area of higher pressure to area of lower pressure
  • 73. A Respiratory Cycle
    • Consists of:
      • an inspiration (inhalation)
      • an expiration (exhalation)
      • Respiration
    • Causes volume changes that create changes in pressure
    • Volume of thoracic cavity changes:
      • with expansion or contraction of diaphragm or rib cage
  • 74. Compliance of the Lung
    • An indicator of expandability
    • Low compliance requires greater force
    • High compliance requires less force
    • Factors That Affect Compliance
    • Connective-tissue structure of the lungs
    • Level of surfactant production
    • Mobility of the thoracic cage
  • 75. Pressure and Volume Changes with Inhalation and Exhalation Figure 23–15
    • Can be measured inside or outside the lungs
    • Normal atmospheric pressure:
      • 1 atm or Patm at sea level: 760 mm Hg
  • 76. Intrapulmonary Pressure
    • Also called intra-alveolar pressure
    • Is relative to P atm
    • In relaxed breathing, the difference between P atm and intrapulmonary pressure is small:
      • about —1 mm Hg on inhalation or +1 mm Hg on expiration
  • 77. Maximum Intrapulmonary Pressure
    • Maximum straining, a dangerous activity, can increase range:
      • from —30 mm Hg to +100 mm Hg
  • 78. Intrapleural Pressure
    • Pressure in space between parietal and visceral pleura
    • Averages —4 mm Hg
    • Maximum of —18 mm Hg
    • Remains below P atm throughout respiratory cycle
  • 79. The Respiratory Pump
    • Cyclical changes in intrapleural pressure operate the respiratory pump:
      • which aids in venous return to heart
      • Tidal Volume
    • Amount of air moved in and out of lungs in a single respiratory cycle
  • 80. Injury to the Chest Wall
    • Pneumothorax:
      • allows air into pleural cavity
    • Atelectasis:
      • also called a collapsed lung
      • result of pneumothorax
  • 81. What are the origins and actions of the respiratory muscles responsible for respiratory movements?
  • 82. The Respiratory Muscles Figure 23–16a, b
    • Most important are:
      • the diaphragm
      • external intracostal muscles of the ribs
      • accessory respiratory muscles :
        • activated when respiration increases significantly
  • 83. The Respiratory Muscles Figure 23–16c, d
  • 84. The Mechanics of Breathing
    • Inhalation:
      • always active
    • Exhalation:
      • active or passive
  • 85. 3 Muscle Groups of Inhalation
    • Diaphragm:
      • contraction draws air into lungs
      • 75% of normal air movement
    • External intracostal muscles:
      • assist inhalation
      • 25% of normal air movement
    • Accessory muscles assist in elevating ribs:
      • sternocleidomastoid
      • serratus anterior
      • pectoralis minor
      • scalene muscles
  • 86. Muscles of Active Exhalation
    • Internal intercostal and transversus thoracis muscles:
      • depress the ribs
    • Abdominal muscles:
      • compress the abdomen
      • force diaphragm upward
  • 87. Modes of Breathing
    • Respiratory movements are classified:
      • by pattern of muscle activity
      • into quiet breathing and forced breathing
  • 88. Quiet Breathing (Eupnea)
    • Involves active inhalation and passive exhalation
    • Diaphragmatic breathing or deep breathing :
      • is dominated by diaphragm
    • Costal breathing or shallow breathing :
      • is dominated by ribcage movements
      • Elastic Rebound
    • When inhalation muscles relax:
      • elastic components of muscles and lungs recoil
      • returning lungs and alveoli to original position
  • 89. Forced Breathing
    • Also called hyperpnea
    • Involves active inhalation and exhalation
    • Assisted by accessory muscles
    • Maximum levels occur in exhaustion
  • 90. Respiratory Rates and Volumes
    • Respiratory system adapts to changing oxygen demands by varying:
      • the number of breaths per minute ( respiratory rate )
      • the volume of air moved per breath ( tidal volume )
  • 91. Respiratory Minute Volume
    • Amount of air moved per minute
    • Is calculated by:
      • respiratory rate  tidal volume
    • Measures pulmonary ventilation
    • Anatomic Dead Space
    • Only a part of respiratory minute volume reaches alveolar exchange surfaces
    • Volume of air remaining in conducting passages is anatomic dead space
  • 92. Alveolar Ventilation
    • Amount of air reaching alveoli each minute
    • Calculated as:
      • tidal volume — anatomic dead space  respiratory rate
    • Alveoli contain less O 2 , more CO 2 than atmospheric air:
      • because air mixes with exhaled air
  • 93. Alveolar Ventilation Rate
    • Determined by respiratory rate and tidal volume:
      • for a given respiratory rate:
        • increasing tidal volume increases alveolar ventilation rate
      • for a given tidal volume:
        • increasing respiratory rate increases alveolar ventilation
  • 94. Respiratory Volumes and Capacities Figure 23–17
  • 95. Lung Volume
    • Total lung volume is divided into a series of volumes and capacities useful in diagnosis
    • Pulmonary Function Tests
    • Measure rates and volumes of air movements
  • 96. 4 Pulmonary Volumes
    • Resting tidal volume:
      • in a normal respiratory cycle
    • Expiratory reserve volume (ERV):
      • after a normal exhalation
    • Residual volume:
      • after maximal exhalation
      • minimal volume (in a collapsed lung)
    • Inspiratory reserve volume (IRV):
      • after a normal inspiration
  • 97. 4 Calculated Respiratory Capacities
    • Inspiratory capacity:
      • tidal volume + inspiratory reserve volume
    • Functional residual capacity (FRC):
      • expiratory reserve volume + residual volume
    • Vital capacity:
      • expiratory reserve volume + tidal volume + inspiratory reserve volume
    • Total lung capacity:
    • vital capacity + residual volume
  • 98. Gas Exchange
    • Occurs between blood and alveolar air
    • Across the respiratory membrane
    • Depends on:
      • partial pressures of the gases
      • diffusion of molecules between gas and liquid
    InterActive Physiology: Respiratory System: Gas Exchange PLAY
  • 99. The Gas Laws
    • Diffusion occurs in response to concentration gradients
    • Rate of diffusion depends on physical principles, or gas laws
      • e.g., Boyle’s law
  • 100. Composition of Air
    • Nitrogen (N 2 ) about 78.6%
    • Oxygen (O 2 ) about 20.9%
    • Water vapor (H 2 O) about 0.5%
    • Carbon dioxide (CO 2 ) about 0.04%
  • 101. Gas Pressure
    • Atmospheric pressure (760 mm Hg):
      • produced by air molecules bumping into each other
    • Each gas contributes to the total pressure:
      • in proportion to its number of molecules ( Dalton’s law )
  • 102. Partial Pressure
    • The pressure contributed by each gas in the atmosphere
    • All partial pressures together add up to 760 mm Hg
  • 103. Henry’s Law Figure 23–18
    • When gas under pressure comes in contact with liquid:
      • gas dissolves in liquid until equilibrium is reached
    • At a given temperature:
      • amount of a gas in solution is proportional to partial pressure of that gas
  • 104. Gas Content & Solubility in body fluids
    • The actual amount of a gas in solution (at given partial pressure and temperature) depends on the solubility of that gas in that particular liquid
    • CO 2 is very soluble
    • O 2 is less soluble
    • N 2 has very low solubility
  • 105. Diffusion and the Respiratory Membrane
    • Direction and rate of diffusion of gases across the respiratory membrane determine different partial pressures and solubilities
  • 106. Efficiency of Gas Exchange
    • Due to:
      • – substantial differences in partial pressure across the respiratory membrane
      • – distances involved in gas exchange are small
      • O 2 and CO 2 are lipid soluble
      • – total surface area is large
      • – blood flow and air flow are coordinated
  • 107. Respiratory Processes and Partial Pressure Figure 23–19 An Overview of Respiratory Processes and Partial Pressures in Respiration PLAY
    • Normal Partial Pressures
    • In pulmonary vein plasma:
      • PCO2 = 40 mm Hg
      • PO2 = 100 mm Hg
      • PN2 = 573 mm Hg
  • 108. O 2 and CO 2
    • Blood arriving in pulmonary arteries has:
      • low P O 2
      • high P CO 2
    • The concentration gradient causes:
      • O 2 to enter blood
      • CO 2 to leave blood
    • Rapid exchange allows blood and alveolar air to reach equilibrium
  • 109. Mixing
    • Oxygenated blood mixes with unoxygenated blood from conducting passageways
    • Lowers the PO 2 of blood entering systemic circuit (about 95 mm Hg)
    Respiration: Gas Mixture in Air PLAY
  • 110. Interstitial Fluid
    • P O 2 40 mm Hg
    • P CO 2 45 mm Hg
    • Concentration gradient in peripheral capillaries is opposite of lungs:
      • CO 2 diffuses into blood
      • O 2 diffuses out of blood
  • 111. How is oxygen picked up, transported, and released in the blood? What is the structure and function of hemoglobin?
  • 112. Gas Pickup and Delivery
    • Blood plasma can’t transport enough O 2 or CO 2 to meet physiological needs
    • Red Blood Cells ( RBCs )
    • Transport O 2 to, and CO 2 from, peripheral tissues
    • Remove O 2 and CO 2 from plasma, allowing gases to diffuse into blood
  • 113. Oxygen Transport
    • O 2 binds to iron ions in hemoglobin (Hb) molecules:
      • in a reversible reaction
    • Each RBC has about 280 million Hb molecules:
      • each binds 4 oxygen molecules -saturated
    • The percentage of heme units in a hemoglobin molecule:
      • that contain bound oxygen
    Respiration: Oxygen and Carbon Dioxide Transport PLAY
  • 114. Oxyhemoglobin Saturation Curve Figure 23–20 (Navigator) Environmental Factors Affecting Hemoglobin PO2 of blood, Blood pH, Temperature Metabolic activity within RBCs
  • 115. Oxyhemoglobin Saturation Curve
    • Is a graph relating the saturation of hemoglobin to partial pressure of oxygen:
      • higher P O 2 results in greater Hb saturation
    • Is a curve rather than a straight line:
      • because Hb changes shape each time a molecule of O 2 is bound
      • each O 2 bound makes next O 2 binding easier
      • allows Hb to bind O 2 when O 2 levels are low
  • 116. Oxygen Reserves
    • O 2 diffuses:
      • from peripheral capillaries (high PO 2 )
      • into interstitial fluid (low PO 2 )
    • Amount of O 2 released depends on interstitial PO 2
    • Up to 3/4 may be reserved by RBCs
    • Carbon Monoxide
    • CO from burning fuels:
      • binds strongly to hemoglobin
      • takes the place of O 2
      • can result in carbon monoxide poisoning
  • 117. pH, Temperature, and Hemoglobin Saturation Figure 23–21
  • 118. The Oxyhemoglobin Saturation Curve
    • Is standardized for normal blood (pH 7.4, 37°C)
    • When pH drops or temperature rises:
      • more oxygen is released
      • curve shift to right
    • When pH rises or temperature drops:
      • less oxygen is released
      • curve shifts to left
  • 119. The Bohr Effect
    • Is the effect of pH on hemoglobin saturation curve
    • Caused by CO 2 :
      • CO 2 diffuses into RBC
      • an enzyme, called carbonic anhydrase, catalyzes reaction with H 2 O
      • produces carbonic acid (H 2 CO 3 )
    • Carbonic acid (H 2 CO 3 ):
      • dissociates into hydrogen ion (H + ) and bicarbonate ion (HCO 3 — )
    • Hydrogen ions diffuse out of RBC, lowering pH
  • 120. 2,3-biphosphoglycerate (BPG)
    • RBCs generate ATP by glycolysis:
      • forming lactic acid and BPG
    • BPG directly affects O 2 binding and release:
      • more BPG, more oxygen released
    • BPG levels rise:
      • when pH increases
      • when stimulated by certain hormones
    • If BPG levels are too low:
      • hemoglobin will not release oxygen
  • 121. Fetal and Adult Hemoglobin Figure 23–22
  • 122. Fetal and Adult Hemoglobin
    • The structure of fetal hemoglobin :
      • differs from that of adult Hb
    • At the same P O 2 :
      • fetal Hb binds more O 2 than adult Hb
      • which allows fetus to take O 2 from maternal blood
  • 123. KEY CONCEPT
    • Hemoglobin in RBCs:
      • carries most blood oxygen
      • releases it in response to low O 2 partial pressure in surrounding plasma
    • If P O 2 increases, hemoglobin binds oxygen
    • If P O 2 decreases, hemoglobin releases oxygen
    • At a given P O 2 :
      • hemoglobin will release additional oxygen
      • if pH decreases or temperature increases
  • 124. How is carbon dioxide transported in the blood? Carbon Dioxide Transport Figure 23–23 (Navigator) Respiration: Carbon Dioxide and Oxygen Exchange PLAY InterActive Physiology: Respiratory System: Gas Transport PLAY
  • 125. Carbon Dioxide (CO 2 )
    • Is generated as a byproduct of aerobic metabolism (cellular respiration)
    • CO 2 in the Blood Stream
    • May be:
      • converted to carbonic acid
      • bound to protein portion of hemoglobin
      • dissolved in plasma
      • Bicarbonate Ions
    • Move into plasma by an exchange mechanism (the chloride shift ) that takes in Cl — ions without using ATP
  • 126. CO 2 in the Blood Stream
    • 70% is transported as carbonic acid (H 2 CO 3 ):
      • which dissociates into H + and bicarbonate (HCO 3 — )
    • 23% is bound to amino groups of globular proteins in Hb molecule:
      • forming carbaminohemoglobin
    • 7% is transported as CO 2 dissolved in plasma
  • 127. KEY CONCEPT
    • CO 2 travels in the bloodstream primarily as bicarbonate ions, which form through dissociation of carbonic acid produced by carbonic anhydrase in RBCs
    • Lesser amounts of CO 2 are bound to Hb or dissolved in plasma
  • 128. Summary: Gas Transport Figure 23–24
  • 129. Control of Respiration
    • Gas diffusion at peripheral and alveolar capillaries maintain balance by:
      • changes in blood flow and oxygen delivery
      • changes in depth and rate of respiration
    InterActive Physiology: Respiratory System: Control of Respiration PLAY
  • 130. Local Regulation of O 2 Transport (1 of 2)
    • O 2 delivery in tissues and pickup at lungs are regulated by:
      • rising P CO 2 levels:
        • relaxes smooth muscle in arterioles and capillaries
        • increases blood flow
      • coordination of lung perfusion and alveolar ventilation:
        • shifting blood flow
      • P CO 2 levels:
        • control bronchoconstriction and bronchodilation
  • 131. Respiratory Centers of the Brain
    • When oxygen demand rises:
      • cardiac output and respiratory rates increase under neural control
    • Have both voluntary and involuntary components
    • Involuntary Centers
    • Regulate respiratory muscles
    • In response to sensory information
  • 132. Voluntary Centers
    • In cerebral cortex affect:
      • respiratory centers of pons and medulla oblongata
      • motor neurons that control respiratory muscles
      • The Respiratory Centers
    • 3 pairs of nuclei in the reticular formation of medulla oblongata and pons
  • 133. Respiratory Rhythmicity Centers of the Medulla Oblongata
    • Set the pace of respiration
    • Can be divided into 2 groups:
      • Dorsal respiratory group (DRG)-
    • Inspiratory center
    • Functions in quiet and forced breathing
    • Inspiratory and expiratory center
    • Functions only in forced breathing
    • Ventral respiratory group (VRG)
  • 134. Quiet Breathing Figure 23–25a
    • Brief activity in the DRG:
      • stimulates inspiratory muscles
    • DRG neurons become inactive:
      • allowing passive exhalation
  • 135. Forced Breathing Figure 23–25b
    • Increased activity in DRG:
      • stimulates VRG
      • which activates accessory inspiratory muscles
    • After inhalation:
      • expiratory center neurons stimulate active exhalation
  • 136. The Apneustic and Pneumotaxic Centers of the Pons
    • Paired nuclei that adjust output of respiratory rhythmicity centers:
      • regulating respiratory rate and depth of respiration
      • An Apneustic Center
    • Provides continuous stimulation to its DRG center
    • Pneumotaxic Centers
    • Inhibit the apneustic centers
    • Promote passive or active exhalation
  • 137. Respiratory Centers and Reflex Controls Figure 23–26
    • Interactions between VRG and DRG:
      • establish basic pace and depth of respiration
    • The pneumotaxic center:
      • modifies the pace
  • 138. SIDS
    • Also known as sudden infant death syndrome
    • Disrupts normal respiratory reflex pattern
    • May result from connection problems between pacemaker complex and respiratory centers
    • Respiratory Reflexes- Changes in patterns of respiration induced by sensory input
  • 139. 5 Sensory Modifiers of Respiratory Center Activities
    • Chemoreceptors are sensitive to:
      • P CO 2 , P O 2 , or pH
      • of blood or cerebrospinal fluid
    • Baroreceptors in aortic or carotic sinuses:
      • sensitive to changes in blood pressure
  • 140. 5 Sensory Modifiers of Respiratory Center Activities
    • Stretch receptors:
      • respond to changes in lung volume
    • Irritating physical or chemical stimuli:
      • in nasal cavity, larynx, or bronchial tree
    • Other sensations including:
      • pain
      • changes in body temperature
      • abnormal visceral sensations
  • 141. Chemoreceptor Reflexes
    • Respiratory centers are strongly influenced by chemoreceptor input from:
      • * cranial nerve IX - The glossopharyngeal nerve:
      • from carotid bodies
      • stimulated by changes in blood pH or P O 2
      • * cranial nerve X -The vagus nerve:
      • from aortic bodies
      • stimulated by changes in blood pH or P O 2
      • * receptors that monitor cerebrospinal fluid-
    • Are on ventrolateral surface of medulla oblongata
    • Respond to P CO 2 and pH of CSF
  • 142. Chemoreceptor Responses to PCO 2 Figure 23–27
  • 143.
    • Hypercapnia - An increase in arterial P CO 2
    • Stimulates chemoreceptors in the medulla oblongata:
      • to restore homeostasis
      • Hypoventilation- A common cause of hypercapnia
    • Abnormally low respiration rate:
      • allows CO 2 build-up in blood
      • Hyperventilation- Excessive ventilation
    • Results in abnormally low P CO 2 ( hypocapnia )
    • Stimulates chemoreceptors to decrease respiratory rate
  • 144. Baroreceptor Reflexes
    • Carotid and aortic baroreceptor stimulation:
      • affects blood pressure and respiratory centers
    • When blood pressure falls:
      • respiration increases
    • When blood pressure increases:
      • respiration decreases
  • 145. Protective Reflexes
    • Triggered by receptors in epithelium of respiratory tract when lungs are exposed to:
      • toxic vapors
      • chemicals irritants
      • mechanical stimulation
    • Cause sneezing, coughing, and laryngeal spasm
  • 146. Apnea
    • A period of suspended respiration
    • Normally followed by explosive exhalation to clear airways:
      • sneezing and coughing
      • Laryngeal Spasm
    • Temporarily closes airway:
      • to prevent foreign substances from entering
  • 147. The Cerebral Cortex and Respiratory Centers
    • Strong emotions:
      • can stimulate respiratory centers in hypothalamus
    • 2. Temporarily closes airway:
      • to prevent foreign substances from entering
    • Anticipation of strenuous exercise:
      • can increase respiratory rate and cardiac output
      • by sympathetic stimulation
  • 148. KEY CONCEPTS
    • A basic pace of respiration is established between respiratory centers in the pons and medulla oblongata, and modified in response to input from:
      • Chemoreceptors, baroreceptors, stretch receptors
    • In general, CO 2 levels, rather than O 2 levels, are primary drivers of respiratory activity
    • Respiratory activity can be interrupted by protective reflexes and adjusted by the conscious control of respiratory muscles
  • 149. Changes in Respiratory System at Birth (1)
    • Before birth:
      • pulmonary vessels are collapsed
      • lungs contain no air
    • During delivery:
      • placental connection is lost
      • blood P O 2 falls
      • P CO 2 rises
    • At birth:
      • newborn overcomes force of surface tension to inflate bronchial tree and alveoli and take first breath
  • 150. Changes in Respiratory System at Birth (2)
    • Large drop in pressure at first breath:
      • pulls blood into pulmonary circulation
      • closing foramen ovale and ductus arteriosus
      • redirecting fetal blood circulation patterns
    • Subsequent breaths:
      • fully inflate alveoli
  • 151. Respiratory Performance and Age Figure 23–28
  • 152. 3 Effects of Aging on the Respiratory System
    • Elastic tissues deteriorate:
      • reducing lung compliance
      • lowering vital capacity
    • Arthritic changes:
      • restrict chest movements
      • limit respiratory minute volume
    • Emphysema:
      • affects individuals over age 50
      • depending on exposure to respiratory irritants ( e.g., cigarette smoke)
  • 153. Integration with Other Systems
    • Maintaining homeostatic O 2 and CO 2 levels in peripheral tissues requires coordination between several systems:
      • particularly the respiratory and cardiovascular systems
  • 154. Coordination of Respiratory and Cardiovascular Systems
    • Improves efficiency of gas exchange:
      • by controlling lung perfusion
    • Increases respiratory drive:
      • through chemoreceptor stimulation
    • Raises cardiac output and blood flow:
      • through baroreceptor stimulation
  • 155. The Respiratory System and Other Systems Figure 23–29
  • 156. SUMMARY (1 of 4)
    • 5 functions of the respiratory system:
      • gas exchange between air and circulating blood
      • moving air to and from exchange surfaces
      • protection of respiratory surfaces
      • sound production
      • facilitating olfaction
    • Structures and functions of the respiratory tract:
      • alveoli
      • respiratory mucosa
      • lamina propria
      • respiratory defense system
  • 157. SUMMARY (2 of 4)
    • Structures and functions of the upper respiratory system:
      • the nose and nasal cavity
      • the pharynx
    • Structures and functions of the larynx:
      • cartilages and ligaments
      • sound production
      • the laryngeal musculature
    • Structures and functions of the trachea and primary bronchi
  • 158. SUMMARY (3 of 4)
    • Structures and functions of the lungs:
      • lobes and surfaces, the bronchi
      • the bronchioles, alveoli and alveolar ducts
      • blood supply to the lungs
      • pleural cavities and membranes
    • Respiratory physiology:
      • external respiration
      • internal respiration
    • Pulmonary ventilation:
      • air movement
      • pressure changes
      • the mechanics of breathing
      • respiratory rates and volumes
  • 159. SUMMARY (4 of 4)
    • Gas exchange:
      • the gas laws
      • diffusion and respiration
    • Gas pickup and delivery:
      • partial pressure
      • oxygen transport (RBCs and hemoglobin)
      • carbon dioxide transport
    • Control of respiration:
      • local regulation (lung perfusion, alveolar ventilation)
      • respiratory centers of the brain
      • respiratory reflexes
      • voluntary control of respiration
    • Changes in the respiratory system at birth
    • Aging and the respiratory system