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NSG 530 Module 5: Respiratory System
Jun 25, 2024
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Respiratory System Lecture Notes
Main Functions of the Lungs
Gas exchange
: Bringing in oxygen and expelling carbon dioxide.
Inhalation
: Diaphragm contracts downward and chest muscles expand chest cavity, sucking in air.
Exhalation
: Diaphragm and chest muscles relax, expelling air.
Pathway of Air
Nasal Cavity
Air enters through nostrils.
Lined with mucus-producing cells (contain lysozymes) to trap dust, pollen, and bacteria.
Nose hairs trap particles forming boogers.
Paranasal Sinuses
Air-filled spaces (frontal, ethmoid, sphenoid, maxillary sinuses).
Warm and moisten air, amplify voice.
Pharynx (Throat)
Nasopharynx connects nasal cavity.
Oropharynx connects oral cavity.
Laryngopharynx connects to larynx.
Soft palate and uvula prevent food from entering nasopharynx.
Larynx (Voice Box)
Epiglottis seals airway during swallowing.
Triggers cough reflex if foreign particles enter.
Trachea (Windpipe)
Splits into two mainstem bronchi.
Right lung has 3 lobes; left lung has 2 lobes.
Right mainstem bronchus more vertical and wider.
Bronchi and Bronchioles
Trachea supported by cartilage rings.
Smooth muscle innervated by autonomic nervous system.
Sympathetic nerves: Dilate airways via beta-2 adrenergic receptors.
Parasympathetic nerves: Constrict airways via muscarinic receptors.
Lined with ciliated columnar cells and goblet cells (mucus).
Mucociliary escalator moves mucus and particles up to pharynx.
Conducting bronchioles lead to respiratory bronchioles.
Terminal bronchioles mark end of conducting bronchioles.
Alveoli and Gas Exchange
Alveoli
(around 500 million)
Tiny outpouchings in respiratory bronchioles.
Transition into alveolar ducts.
Lined by pneumocytes (thin epithelial cells).
Type I Pneumocytes
: Main structural cells.
Type II Pneumocytes
: Secrete surfactant, can transform into Type I.
Blood-Gas Barrier
Alveolar wall, basement membrane, and capillary wall facilitate gas exchange.
Carbon dioxide diffuses from blood to alveoli to be exhaled.
Oxygen diffuses from alveoli to blood to be distributed throughout the body.
Alveolar Macrophages
Capture particles, ride mucociliary escalator to pharynx.
Summary
Respiratory system
: Facilitates gas exchange.
Pathway: Nostril -> Nasal cavity -> Pharynx -> Larynx -> Trachea -> Bronchi -> Conducting bronchioles -> Respiratory bronchioles -> Alveoli -> Capillary.
Oxygen inhaled, carbon dioxide exhaled.
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