Respiratory System Applied Anatomy.pdf

THE RESPIRATORY SYSTEM Applied Anatomy Karen Sam, PT, DPT, GCS West Coast University PT 731 Physiology Fall 2023 Respiratory System - 5 Functions 1. Gaseous Exchange - between atmosphere and blood through an extensive surface area 2. Homeostatic regulation of pH - Lungs can alter body pH by sel...

THE RESPIRATORY SYSTEM Applied Anatomy Karen Sam, PT, DPT, GCS West Coast University PT 731 Physiology Fall 2023 Respiratory System - 5 Functions 1. Gaseous Exchange - between atmosphere and blood through an extensive surface area 2. Homeostatic regulation of pH - Lungs can alter body pH by selectively retaining or excreting CO2 3. Protection from inhaled pathogens and irritating substances 4. Vocalization - Air moving across vocal cords for speech, singing, and communication 5. Participate in olfactory sense K Sam Fall 2023 Thoracic Cage • Ribs • True ribs (1- 7) – vertebrosternal ribs • False ribs (8 -12) • Ribs 8 – 10 – vertebrochondral ribs – attached to the rib above by their costal cartilages • Floating ribs 11-12 – vertebral ribs K Sam Fall 2023 https://gr.pinterest.com/pin/449093394077242600/?amp_client_id=CLIE NT_ID(_)&mweb_unauth_id={{default.session}}&simplified=true Thoracic Cage • Sternum • Superior border: Suprasternal notch (or jugular notch) • “Angle of Louis” or Sternal Angle (@ T4 / 5) • level of bifurcation of trachea into right and left main stem bronchi • Marks the upper margin of the heart and the beginning and end of the aortic arch • Sternal body articulates with ribs 3 to 7 http://understandingmaddismedicine.blogspot.com/2012/10/t horacic-cage-intercostal-spaces.html K Sam Fall 2023 Thoracic Movement at Inspiration 1. Elevation of rib cage 2. Pump handle movement of rib and sternum • @ Upper ribs • Increases AP diameter 3. Buckle handle of ribs • @ Lower ribs • Increase transverse diameter K Sam Fall 2023 Muscles of Ventilation o o o Muscles of Inspiration ▪ Diaphragm ▪ External intercostals ▪ Accessory muscles • SCM, scalenes, upper traps, pect major and minor, serratus anterior, rhomboids, subclavius • Thoracic erector spinae, latissimus dorsi, serratus posterior superior Expiration - passive at rest due to elastic recoil Muscles of Forced/Active Exhalation ▪ Internal intercostals; transversus thoracis ▪ Rectus abdominis, external obliques, internal obliques, transverse abdominis K Sam Fall 2023 Expiration Mechanics & Muscles • Muscles of forced (active) exhalation – to produce a quicker and/or fuller exhalation 1. Internal intercostals (& transversus thoracis) • Pulls the ribs down 2. Abdominal muscles • Compress abdomen • Push diaphragm upward K Sam Fall 2023 Lungs • Light, spongy tissues; volume is mostly air-filled spaces • Cone-shaped • Asymmetry: • Right slightly larger than Left Netter F: Clinical Symposia, Vol 17, No. 3, 1965 K Sam Fall 2023 Lungs – Anatomic Landmarks • Apex • Base • 3 Borders – Anterior, Posterior, Inferior. • 3 Surfaces – Costal, Medial, Diaphragmatic. • Hilum – the point at which the nerves, vessels, and primary bronchi penetrate the parenchyma • Roots – suspends the lungs —including principal bronchus, pulmonary artery, pulmonary veins, bronchial arteries/veins, pulmonary nerve plexus, and lymph vessels K Sam Fall 2023 Pleurae • Each lung is covered by a double-walled pleural sac, which contains a thin amount of viscous pleural fluid • visceral and parietal pleurae • Pleural cavities are entirely separated by mediastinum • Helps to confine infection K Sam Fall 2023 Pleurae (cont.) • Negative pressure between pleurae (intrapleural pressure) maintains lung inflation • Pleural fluid • creates a moist, slippery surface so membranes can slide across each other • The bond between membranes makes lungs held to the thoracic cage and holds them stretch in a partially inflated state even at rest. K Sam Fall 2023 Organization of the Respiratory System The respiratory system is divided into • • Upper respiratory system: above the larynx Lower respiratory system: below the larynx K Sam Fall 2023 Upper Respiratory Tract - Ventilation Ventilation = movement of air in/out of lungs 1. Nasal cavities 2. Pharynx (throat): passageway for respiratory and digestive systems • Nasopharynx – behind nasal cavity • Oropharynx – behind the mouth • Laryngopharynx – opens into the larynx anteriorly and esophagus posteriorly K Sam Fall 2023 https://my.clevelandclinic.org/health/body/21869-pharynx Upper Respiratory Tract – Ventilation (cont.) 3. Larynx • To conduct air between the pharynx and trachea • Epiglottis – leaf-shaped cartilage closes and protects the respiratory tract during swallowing • Also houses the Vocal Folds • Glottis – the opening between the vocal folds K Sam Fall 2023 https://www.visiblebody.com/hs-fs/hub/189659/file-2549146283-png/Phonation-Laryngeal-Skeleton-Larynx-Vocal-Folds.png https://healthjade.net/thyroid-cartilage/ Upper Respiratory Tract – Ventilation (cont.) 3. Larynx (cont.) • Formed by cartilage • Cricoid cartilage • Tracheal cartilage https://www.istockphoto.com/vector/tracheostomy-cross-section-diagram-vector-illustrationgm1206867484-348235395 K Sam Fall 2023 https://www.nejm.org/doi/full/10.1056/NEJMvcm2014884 Lower Respiratory Tract – Ventilation+Respiration • Lower respiratory tract • From lower margins of cricoid cartilage → Alveoli • Tracheobronchial tree—conducting airways • • • • • • • Trachea Mainstem bronchi lobar (2o) bronchi – upper, middle/lingular, lower Segmental (3o)bronchi Bronchioles / Conducting bronchioles Terminal bronchioles Terminal respiratory units (Acinar unit) • Respiratory bronchioles • Alveolar ducts (1-3) • Alveolar sacs • Alveoli K Sam Fall 2023 https://en.wikipedia.org/wiki/Respiratory_tract_infection Tracheobronchial Tree - Structure • Airway diameter – progressively decreases with each succeeding generation of branching • ~ 1 in at trachea → < 1 mm at terminal bronchioles • As bronchioles divide and branches become smaller, there is less cartilage and more smooth muscle and elastic fibers • The cartilages gradually change from “C” shaped to irregular plates to minute rods and disappear at the bronchiolar level • @Terminal bronchioles: elastic tissue + smooth muscle fibers, no cartilage or goblet cells K Sam Fall 2023 Tracheobronchial Tree – Structure (cont.) Right vs. Left Mainstem Bronchi • Right – more vertical, wider, ~1 long, 25° angle from line extended from trachea • Left – more horizontal, ~2 long, diverges at 40-60 ° angle from trachea • Aspiration, therefore, is more common in the Right lung. • Right lower lobe pneumonia on CXR more suspicious of aspiration (RIGHT) K Sam Fall 2023 Functional Divisions • Conducting zone – before terminal bronchioles – • Anatomical dead space • Ventilation only • Transitional zone • consists of the respiratory bronchioles, which have alveoli present in the walls of the bronchioles • Respiration AND ventilation both occur in the TZ • Respiratory zone • includes the alveolar ducts and alveoli • ONLY respiration occurs in the RZ K Sam Fall 2023 From McArdle WD, Katch FI, Katch VL: Essentials of Exercise Physiology, 2nd Ed. Lippincott Williams & Wilkins, 2000 Terminology Parenchyma: • The functional tissue • Portion of the lung involved in gas exchange • Alveoli, alveolar ducts, respiratory bronchioles K Sam Fall 2023 Terminology Interstitium: • A collection of support tissues within the lung • Bronchial and Alveolar epithelium • Pulmonary capillary epithelium • Basement membrane • Peri-vascular and peri-lymphatic tissues K Sam Fall 2023 Components of the Respiratory System Respiratory Mucosa • consists of – • Epithelial layer: Respiratory Epithelium • Epithelium lines respiratory tract • Moistens and protects airways • Bathed in a layer of watery saline produced by epithelial cells. 1. Bronchial Epithelium 2. Alveolar Epithelium K Sam Fall 2023 Respiratory Epithelium 1. Bronchial Epithelium • @Upper, conducting airways – pseudostratified, columnar, ciliated epithelium • @Terminal and Respiratory bronchioles – single-layered, cuboidal, non-ciliated epithelium K Sam Fall 2023 (Top) https://courses.lumenlearning.com/cuny-kbcc-ap2/chapter/organs-and-structures-of-the-respiratory-system/ (Bottom:) https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/64-gas-exchange/pneumocytes.html Along the Conducting Airways Cilia • tiny muscular, hair-like projections on the cells that line the airway Goblet cells • mucus-secreting • more in the trachea and large airways, progressively less distally • Mucous contains immunoglobulins (IgA) that can disable many pathogens. Areolar layer: Lamina Propria • Lines the conducting portion of the respiratory system – line underneath the bronchial epithelium K Sam Fall 2023 Defense Mechanisms Mucociliary Transport / Escalator A self-clearing mechanism between bronchi to larynx • Mucus layer line the trachea • traps pathogens & other particles • mucus contains IgA • Cilia sweep and propel the pathogens and particles to the trachea and cough out or move to the mouth and swallow https://youtu.be/HMB6flEaZwI K Sam Fall 2023 (Top right) https://commons.wikimedia.org/wiki/File:Blausen_0766_RespiratoryEpithelium.png (Top left) https://slideplayer.com/slide/17101351/ Respiratory Epithelium (cont.) 2. Alveolar Epithelium • For gases to exchange efficiently • Very thin Alveoli walls (<1 µm) • Significant Surface area (about 35 times the surface area of the body of alveoli) • Type I pneumocytes: large flat cells compose the majority of the alveolar surface • Type II pneumocytes: ovoid cells involved in the synthesis of surfactant – reduces surface tension in the alveoli and prevent the air sacs from collapsing during exhalation K Sam Fall 2023 (Top) https://courses.lumenlearning.com/cuny-kbcc-ap2/chapter/organs-and-structures-of-the-respiratory-system/ (Bottom:) https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/64-gas-exchange/pneumocytes.html Lower Respiratory Tract – Ventilation + Respiration • Lower respiratory tract (cont.) • Terminal respiratory units (Acinar unit) • Respiratory bronchioles • Alveolar ducts (1-3) • Atrium • Alveolar sacs • Alveoli K Sam Fall 2023 https://en.wikipedia.org/wiki/Respiratory_tract_infection Communication - to allow Collateral Ventilation • Lambert’s • canals alveoli communicate with bronchioles • Kohn’s pores aka inter-alveolar connection or alveolar pores • alveoli communicate with one another • • Alveoli are like balloons, this intimate communication between structures allow air to fill the lungs at a relatively same speed - and facilitate uniform lung expansion • allow even dispersion of surfactant – reduce surface tension for easier alveolar inflation • K Sam Fall 2023 Acinus = Alveolar Capillary Unit The Organ/Site of Gas Exchange = RESPIRATION: 1. Alveolar Surface – for diffusion • A single layer of epithelium (Epithelial cells, surfactant, macrophage) 2. Capillary Endothelium K Sam Fall 2023 1st Defense Mechanisms • Particles, such as dust and soot, mold, fungi, bacteria, and viruses deposit on airway and alveolar surfaces. • 1st line of defense (reference diagram): • Physical barriers – prevent entry of pathogen • Nasal hairs – filter out (larger) particles • Nasal mucosa – warms and humidifies inhaled air, hydrates and enlarges airborne particles • Reflexes: • Sneezing • Coughing • Gagging • Bronchospasm K Sam Fall 2023 Phases of Cough 1. Inspiratory Phase: Deep inspiration greater than tidal volume (≥60% of Vital Capacity) 2. Compressive Phase: • Glottis closure • Increase intraabdominal and intrathoracic pressures 3. Expiratory Phase: • Forceful abdominal and intercostal muscle contraction • Sudden opening of the glottis and forceful expulsion of inspired air All phases must function adequately for a cough to be effective. K Sam Fall 2023 https://pharmaceutical-journal.com/article/ld/case-based-learning-cough 2nd Defense Mechanisms Mucociliary Transport / Escalator https://youtu.be/HMB6flEaZwI • A self-clearing mechanism between bronchi to larynx • Mucus layer line the trachea • • • Cilia • • traps pathogens & other particles mucus – produced by Goblet cells – contained IgA - tiny muscular, hair-like projections on the cells that line the airway Pathogens and particles that are trapped on the mucus layer are swept and propelled to trachea and coughed out, or moved to the mouth and swallowed K Sam Fall 2023 (Top right) https://commons.wikimedia.org/wiki/File:Blausen_0766_RespiratoryEpithelium.png (Top left) https://slideplayer.com/slide/17101351/ 2nd Defense Mechanisms (cont.) Mucociliary Transport / Escalator • mucus production increases with inflammation • mucus consistency may be changed by disease • Asthma: Respiratory mucosa may thicken with inflammation or infiltration • Mucociliary transport can be impaired by inhalation of toxic gases, acute inflammation, infection, other disease processes K Sam Fall 2023 3rd Defense Mechanisms Alveolar Macrophages – roaming on surface of alveoli • Because of the requirements of gas exchange, alveoli are not protected by mucus and cilia—mucus is too thick and would slow down movement of oxygen and carbon dioxide. • Instead, alveolar macrophages seek out deposited particles, bind to them, ingest them, kill any that are living, and digest them. K Sam Fall 2023 https://courses.lumenlearning.com/cuny-kbccap2/chapter/organs-and-structures-of-the-respiratory-system/ 3rd Defense Mechanisms (cont.) • When the lungs are exposed to serious threats, additional white blood cells in the circulation, especially neutrophils, can be recruited to help ingest and kill pathogens. For example, when the person inhales a great deal of dust or is fighting a respiratory infection, more macrophages are produced, and neutrophils are recruited. K Sam Fall 2023 https://courses.lumenlearning.com/cuny-kbccap2/chapter/organs-and-structures-of-the-respiratory-system/