The Respiratory System Part 1 PDF

The Respiratory System Part 1 DES JARDINS Chapter 1 Introduction Primary function of the respiratory system: Absorption of O2 and excretion of CO2 External respiration Gas exchange between the gas of the atmosphere and blood Internal respiration Gas exchange between tissue cells and systemic capilla...

The Respiratory System Part 1 DES JARDINS Chapter 1 Introduction Primary function of the respiratory system: Absorption of O2 and excretion of CO2 External respiration Gas exchange between the gas of the atmosphere and blood Internal respiration Gas exchange between tissue cells and systemic capillary blood The system brings gas into close proximity with the flowing blood in the pulmonary circulatory system 2 Introduction (Cont.) The respiratory system includes: Upper airways, chest wall, respiratory muscles, lower airways, pulmonary blood vessels, support nerves, and lymphatics Also humidifies and warms inspired air while removing inhaled contaminants and filtering out chemicals. 3 Conducting Airways Passageways between ambient environment and alveoli No gas exchange occurs but important to ventilation Upper airways and lower airways 4 Upper Respiratory Tract (URT) Defined as airways starting at the nose, extend to trachea Composed of Nasal cavities and sinuses Oral cavity Pharynx Larynx 5 Upper Respiratory Tract (Cont.) 6 Functions of the Upper Airways Passageway for gas flow Filter Heater Humidification Sense of smell and taste Phonation (vocal cords are located in the larynx) Protection of the lower airways 7 Nasal Cavity External nares give entrance into cavities Vestibules contain gross hairs working as filter Concha or turbinates—three shelf like bones projecting from lateral walls Function: Increase surface area for filtering, warming, and humidifying inhaled gases Contain olfactory cells providing sense of smell Surface fluid is provided by goblet cells and submucosal glands in cavity and sinuses 8 Sinuses Hollow spaces in the facial bones Four sets of sinuses Frontal, ethmoid, sphenoid, maxillary Function of sinuses Reduce weight of head Strengthen skull Modify voice during phonation Copyright © 2017 Elsevier Inc. All Rights Reserved. 9 Sinuses (Cont.) 10 Oral Cavity Vestibule Tongue Intrinsic muscles Extrinsic muscles0 Lingual frenulum Hard palate Soft palate Palatine arches Forms common passage for air, food, and fluids Posterior portion of tongue has nerve endings triggering 11 gag reflex to protect airway Pharynx Oral and nasal cavities open into the pharynx Nasopharynx (from nasal cavity to uvula) Adenoids lie right where many particles impact Eustachian tubes link to middle ear Oropharynx (from uvula to tip of epiglottis) Palatine tonsils (removed in tonsillectomy) Vallecula epiglottica- important landmark for insertion of endotracheal tube Laryngopharynx –hypopharynx (tip epiglottis to larynx) Anatomic location where respiratory and digestive tracts divide Pharyngeal reflex(aka “gag reflex”) 12 Copyright © 2017 Elsevier Inc. All Rights Reserved. 13 Larynx Contains nine cartilages Thyroid (Adam’s apple) Cricoid falls just below thyroid cartilage Epiglottis attaches to thyroid cartilage Vocal folds False- no role in vocalization True- “vocal cords” Glottis- space between vocal cords 14 Larynx (Cont.) 15 Larynx (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 16 Patent Upper Airway Relative positions of oral cavity, pharynx, and larynx are major determinant of patency, particularly in unconscious patient Head tilts forward, partial or total occlusion can occur Extend head into “sniff position” to open airway and facilitate artificial airway insertion Patent = OPEN! 18 Patent Upper Airway (Cont.) 19 Lower Respiratory Tract Everything distal to larynx Made up of conducting and respiratory airways Conducting airways—first 15 generations Purpose: convey gas from URT to area of gas exchange (lung parenchyma) Respiratory airways Microscopic airways distal to conducting zone Participate in gas exchange with blood Copyright © 2017 Elsevier Inc. All Rights Reserved. 20 Histology of Airway Wall Conducting airways (trachea to bronchioles) Walls constructed of three layers Mucosa—inner layer forms mucous membrane Composed of epithelia Pseudostratified, ciliated, goblet cells, columnar epithelia—most numerous cell type Submucosa—composed of connective tissue, bronchial glands, and smooth fibers that wrap around airway Adventitia—outer covering of connective tissue Copyright © 2017 Elsevier Inc. All Rights Reserved. 21 Lobar and Segmental Pulmonary Anatomy (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 22 Histology of Airway Wall (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 23 Cilia Tiny hair like structures Help propel mucus toward the pharynx “mucociliary escalator” Cigarette smoking, O2 and some drugs can impede cilia action! Copyright © 2017 Elsevier Inc. All Rights Reserved. 24 Cartilaginous AirwaysTrachea and Bronchi Trachea: extends below cricoid cartilage to sternal angle “windpipe” 11-13 cm long, 1.5-2.5 cm in diameter Extends to the level of the 5th thoracic vertebrae Divides into right and left main stem bronchi Bifurcated at the carina Anterior and sides supported by 15 to 20 C-shaped cartilage Trachealis muscle connects tips of C-shaped cartilage and forms posterior wall 25 Trachea and Bronchi (Cont.) 26 Trachea and Bronchi (Cont.) Right bronchus branches at about 25 degree angle Due to angle, most foreign aspirate goes to right lower lobe Left bronchus branches at 40-60 degrees Because of angles, respiratory therapists are careful to monitor the depth of an artificial airway 27 Trachea and Bronchi (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 28 Branches of Bronchi Lobar bronchi- second generation Segmental bronchi- third generation Subsegmental bronchi- fourth-ninth generation Generation continue until bronchi reach diameter of less than 1-mm and connective tissue sheaths disappear Copyright © 2017 Elsevier Inc. All Rights Reserved. 29 Lobar and Segmental Pulmonary Anatomy Each segment is supplied by segmental bronchus These further divide numerous times until conducting airways end in terminal bronchiolessmallest airway! All airways up to this point constitute anatomic deadspace. Meaning: they do NOT participate in gas exchange as the alveoli do! ~2 ml/kg of lean body weight, typically 150 ml 30 Lobar and Segmental Pulmonary Anatomy Each lung is divided into lobes and segments Right lung has 3 lobes and 10 segments Left lung has 2 lobes and 8 or 10 segments Copyright © 2017 Elsevier Inc. All Rights Reserved. 31 Noncartilaginous Airways Bronchioles- tenth to fifteenth generations Cartilage absent Terminal bronchioles- sixteenth to nineteenth generations About 0.5 mm in diameter Cilia and mucous glands disappear Thinner, small channels in terminal bronchioles= canals of Lambert Copyright © 2017 Elsevier Inc. All Rights Reserved. 32 Sites of Gas Exchange Alveoli Primary function is gas exchange 15 to 20 grapelike clusters at the end of the terminal bronchioles Manufacture and storage of surfactant Reduces surface tension and alveolar tendency to collapse Increases compliance and decreases work of breathing Respiratory bronchioles, alveolar ducts and alveolar clusters make up the primary lobule Also known as acinus, lung parenchyma, terminal respiratory unit and functional units 33 Copyright © 2017 Elsevier Inc. All Rights Reserved. 34 Sites of Gas Exchange Alveolar epithelium Two cell types Type I- squamous pneumocyte 95% of alveolar surface Major sites of alveolar gas exchange Unable to reproduce Type II- granular pneumocyte 5% of alveolar surface Primary source of surfactant Pores of Kohn Permit gas to move between alveoli Copyright © 2017 Elsevier Inc. All Rights Reserved. 35 Sites of Gas Exchange Alveolar Macrophages Type III alveolar cells Play major role in removing bacteria and foreign particles that deposit within acini Interstitium Gel like substance that are held together by web-like network of collagen fibers Tight space- between alveolar epithelium and endothelium of pulmonary capillaries Loose space- surrounds bronchioles and primary lobule Copyright © 2017 Elsevier Inc. All Rights Reserved. 36 To Be Continued… Pulmonary Circulation Lymphatics Nervous Control Lungs Thoracic Structures Copyright © 2017 Elsevier Inc. All Rights Reserved. 37