respiratory system physiology

    Cards (91)

    • Major Respiratory Organs
      • Nasal cavity
      • Oral cavity
      • Epiglottis
      • Glottis
      • Trachea
      • Right lung
      • Primary bronchi
      • Secondary bronchi
      • Tertiary bronchi
      • Bronchioles
      • Terminal bronchioles
      • Diaphragm
      • Left lung
      • Esophagus
      • Larynx
      • Pharynx
    • Conducting Zone
      • Air passageway: 150 mL in volume (dead space)
      • Increases air temperature to body temperature
      • Humidifies air
      • Epithelium has goblet cells that secrete mucus
      • Epithelium has ciliated cells that move particles toward mouth
    • Respiratory Zone
      • Respiratory bronchioles
      • Alveolar ducts
      • Alveolar sacs
      • Alveoli
    • Alveoli
      • Site of gas exchange
      • 300 million alveoli in the lungs (size of tennis court)
      • Rich blood supply: capillaries form sheet over alveoli
      • Alveolar pores
      • Type I alveolar cells make up wall of alveoli
      • Type II alveolar cells secrete surfactant
      • Alveolar macrophages
    • Respiratory Membrane
      • Epithelial cell layer of alveoli (type I)
      • Endothelial cell layer of capillaries
      • 0.2 μm thick
    • Structures of the Thoracic Cavity
      • Chest wall: rib cage, sternum, thoracic vertebrae, connective tissue, intercostal muscles
      • Diaphragm
      • Pleural sac around each lung
      • Intrapleural space filled with intrapleural fluid (Volume = 15 mL)
    • Chest Wall
      • Airtight, protects lungs
    • Pleural Sac
      Membrane lining of lungs and chest wall
    • Intrapleural Space

      Filled with intrapleural fluid
    • Air Movement
      • Air moves in and out of lungs by bulk flow
      • Pressure gradient drives flow
      • Air moves from high to low pressure
    • Inspiration
      Pressure in lungs less than atmospheric pressure
    • Expiration
      Pressure in lungs greater than atmospheric pressure
    • Atmospheric Pressure
      • 760 mm Hg at sea level
      • Decreases as altitude increases
      • Increases under water
    • Intra-alveolar Pressure (Palv)
      • Pressure of air in alveoli
      • Given relative to atmospheric pressure
      • Varies with phase of respiration
      • During inspiration = negative (less than atmospheric)
      • During expiration = positive (more than atmospheric)
    • Intrapleural Pressure (Pip)
      • Pressure inside pleural sac
      • Always negative under normal conditions
      • Always less than Palv
      • Varies with phase of respiration
      • At rest, –4 mm Hg
      • Negative due to elasticity in lungs and chest wall
      • Pneumothorax occurs when air enters the pleural space, causing the lung to collapse
    • Transpulmonary Pressure
      • Transpulmonary pressure = Palv – Pip
      • Distending pressure across the lung wall
      • Increase in transpulmonary pressure increases distending pressure across lungs and causes lungs (alveoli) to expand, increasing volume
    • Boyle's Law
      • Pressure is inversely related to volume
      • If amount of gas is the same and container size is reduced, pressure will increase
      • P1V1 = P2V2
    • Determinants of Intra-alveolar Pressure
      • Quantity of air in alveoli
      • Volume of alveoli
      • Lungs expand—alveolar volume increases, Palv decreases, pressure gradient drives air into lungs
      • Lungs recoil—alveolar volume decreases, Palv increases, pressure gradient drives air out of lungs
    • Respiratory Muscles
      • Inspiratory muscles: diaphragm, external intercostals
      • Expiratory muscles: internal intercostals, abdominal muscles
    • Inspiration
      1. External intercostals contract
      2. Diaphragm contracts
      3. Chest wall and lungs expand
    • Expiration
      1. External intercostals relax
      2. Diaphragm relaxes
      3. Chest cavity and lungs contract
      4. Internal intercostals and abdominals contract for active expiration only
    • Pulmonary pressures
      Pressures related to the lungs and breathing
    • Atmospheric pressure is 760 mm Hg at sea level, decreases as altitude increases, increases under water
    • Mechanics of breathing
      Mechanisms for creating pressure gradients that drive air movement in and out of the lungs
    • Inspiratory muscles
      • Diaphragm, external intercostals - increase volume of thoracic cavity
    • Expiratory muscles
      • Internal intercostals, abdominal muscles - decrease volume of thoracic cavity
    • Inspiration
      1. Neural stimulation of inspiratory muscles
      2. Diaphragm contraction, chest wall expansion
      3. Intrapleural pressure decreases, transpulmonary pressure increases
      4. Alveoli expand, Palv decreases, air flows in
    • Expiration
      1. Normally passive, inspiratory muscles stop contracting
      2. Lungs and chest wall recoil, volume decreases
      3. Active expiration uses expiratory muscles for faster volume decrease
    • Lung compliance
      Ease with which lungs can be stretched, larger compliance means easier inspiration
    • Factors affecting lung compliance
      • Elasticity (ability to resist stretch)
      • Surface tension of lungs (surfactant decreases tension and increases compliance)
    • Airway resistance
      Pressure gradient needed for air flow, normally low at ~1 mm Hg, increase makes breathing harder
    • Factors affecting airway resistance
      • Contractile activity of smooth muscle (bronchoconstriction increases, bronchodilation decreases resistance)
      • Mucus secretion
    • Extrinsic control of bronchiole radius
      • Autonomic nervous system (sympathetic relaxation, parasympathetic contraction of smooth muscle)
      • Hormonal control (epinephrine relaxation)
    • Intrinsic control of bronchiole radius
      • Histamine (bronchoconstriction, increased mucus)
      • CO2 (bronchodilation)
    • Respiratory volumes
      Measurements of the amount of air in the lungs at different stages of the breathing cycle
    • Respiratory capacities
      Sums of two or more respiratory volumes
    • Total lung volume is divided into a series of volumes (4) and capacities (4) useful in diagnosing problems
    • Tidal volume (VT)

      Amount of air taken in during inhalation (~500 mL), with ~350 mL entering the alveoli and ~150 mL remaining in the conducting passageways (anatomic dead space)
    • Respiratory rate (f)
      12-20 breaths per minute
    • Inspiratory reserve volume (IRV)
      Maximum air inspired at the end of a normal inspiration (~3000 mL)
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