1 structure and function of the pulmonary system chapter 32
TRANSCRIPT
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Structures of the Pulmonary System Airways Blood vessels Chest wall Lungs
Lobes Segments Lobules
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Structures of the Pulmonary System Conducting airways
Upper airways Nasopharynx Oropharynx
Larynx Connects upper and lower airways
Lower airways Trachea Bronchi Terminal bronchioles
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Structures of the Pulmonary System Gas-exchange airways
Respiratory bronchioles Alveolar ducts Alveoli
Epithelial cells Type I alveolar cells
Alveolar structure Type II alveolar cells
Surfactant production
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Pulmonary and Bronchial Circulation Pulmonary circulation has a lower pressure
than the systemic circulation One third of pulmonary vessels are filled with
blood at any given time Pulmonary artery divides and enters the lung
at the hilus Each bronchus and bronchiole has an
accompanying artery or arteriole
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Pulmonary and Bronchial Circulation Alveolocapillary membrane
Formed by the shared alveolar and capillary walls Thin membrane of alveolar epithelium, the
alveolar basement membrane, interstitial space, the capillary basement membrane, and the capillary endothelium
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Chest Wall and Pleura Chest wall
Skin, ribs, and intercostal muscles Thoracic cavity
Pleura Serous membrane Parietal and visceral layers Pleural space (cavity) Pleural fluid
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Function of the Pulmonary System Ventilation
Mechanical movement of gas or air into and out of the lungs
Minute volume Ventilatory rate multiplied by the volume of air per
breath
Alveolar ventilation
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Ventilation Neurochemical control
Respiratory center Dorsal respiratory group Ventral respiratory group Pneumotaxic center Apneustic center
Peripheral chemoreceptors
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Ventilation Neurochemical control
Lung receptors Irritant receptors Stretch receptors J-receptors
Chemoreceptors Central chemoreceptors Peripheral chemoreceptors
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Mechanics of Breathing Major and accessory muscles
Major muscles of inspiration Diaphragm External intercostals
Accessory muscles of inspiration Sternocleidomastoid and scalene muscles
Accessory muscles of expiration Abdominal and internal intercostal muscles
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Mechanics of Breathing Alveolar surface tension
Function of surfactant Elastic properties of the lung and chest wall
Elastic recoil Compliance
Airway resistance Work of breathing
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Measurement of Gas Pressure Barometric pressure
Partial pressure Partial pressure of water vapor
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Gas Transport Four steps
Ventilation of the lungs Diffusion of oxygen from the alveoli into the
capillary blood Perfusion of systemic capillaries with oxygenated
blood Diffusion of oxygen from systemic capillaries
into the cells Diffusion of CO2 occurs in reverse order
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Gas Transport Distribution of ventilation and perfusion
Gravity and alveolar pressure Ventilation-perfusion ratio
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Gas Transport Oxygen transport
Diffusion across the alveolocapillary membrane Determinants of arterial oxygenation Oxyhemoglobin association and dissociation
Oxyhemoglobin dissociation curve
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Gas Transport Carbon dioxide transport
Dissolved in plasma Bicarbonate Carbamino compounds
Haldane effect
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Control of Pulmonary Circulation Hypoxic vasoconstriction
Caused by low alveolar pO2
Blood is shunted to other, well-ventilated portions of the lungs Provides better ventilation and perfusion matching If hypoxia affects all segments of the lungs, the
vasoconstriction can result in pulmonary hypertension
Acidemia also causes pulmonary artery constriction
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Tests of Pulmonary Function Spirometry Diffusion capacity Residual volume Functional reserve capacity (FRC) Total lung capacity Arterial blood gas analysis Chest radiographs
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Aging and the Pulmonary System Loss of elastic recoil Stiffening of the chest wall Alterations in gas exchange Increases in flow resistance