ECU Lecture 6 PDF - Respiratory System 1

MHS1102D: RESPIRATORY SYSTEM 1  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system  Describe the anatomy of the component parts of the respiratory system  Describe the anatomy of the pharynx, larynx a...

MHS1102D: RESPIRATORY SYSTEM 1  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system  Describe the anatomy of the component parts of the respiratory system  Describe the anatomy of the pharynx, larynx and trachea  Describe the arrangement of the lungs and pleura, and bronchial tree  Name the muscles of respiration and describe their roles  THE RESPIRATORY SYSTEM  Respiration - refers to ventilation of lungs (breathing)  Functions of respiration include: 1. gas exchange: O2 & CO2 exchanged between blood & air 2. communication: speech & other vocalizations 3. olfaction: sense of smell 4. Acid-Base balance: influences pH of body fluids by eliminating CO2  THE RESPIRATORY SYSTEM Functions of respiration (Continued) 5. blood pressure regulation: helps in synthesis of angiotensin II 6. blood & lymph flow: breathing creates pressure gradients between thorax & abdomen that promote flow of lymph & blood 7. blood filtration: lungs filter small clots 8. expulsion of abdominal contents: breath-holding assists in urination, defecation, & childbirth [Valsalva manoeuver]  ANATOMY OF THE RESPIRATORY SYSTEM Principal organs  nose  pharynx  larynx  trachea  bronchi  lungs  incoming air stops in the alveoli  millions of thin-walled, microscopic air sacs  exchange gases with bloodstream & air flows back out  ANATOMY OF THE RESPIRATORY SYSTEM Conducting portion of respiratory system  includes those passages that serve only for airflow  nostrils through to bronchioles  no gas exchange Respiratory portion of respiratory system  comprises alveoli & other gas exchange regions  ANATOMY OF THE RESPIRATORY SYSTEM  Upper respiratory tract - in head & neck  nose through to larynx  Lower respiratory tract - organs within thorax  trachea through to lungs Figure 22.1 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  ANATOMY OF UPPER RESPIRATORY TRACT Figure 22.3c Copyright © McGraw-Hill Education. Permission required for reproduction or display.  UPPER RESPIRATORY TRACT Nasal Hard Soft septum palate palate Uvula Epiglottis Larynx Vocal cords Photos © McGraw-Hill Education  THE NOSE  warms, cleanses & humidifies inhaled air  lined with stratified squamous epithelium  vibrissae: stiff hairs that prevent debris from entering nose  detects odors  serves as a resonating chamber that amplifies voice  extends from nostrils (nares) to posterior nasal apertures (choanae)  facial part is shaped by bone & hyaline cartilage  superior half: nasal bones & maxillae  inferior half: lateral & alar cartilages  ala nasi: flared portion at lower end of nose shaped by alar cartilages & dense connective tissue  ANATOMY OF THE NASAL REGION Figure 22.2a,b © McGraw-Hill Education/Joe DeGrandis, photographer  THE NOSE  nasal septum divides nasal cavity  composed of bone & hyaline cartilage  septal cartilage forms anterior part  roof & floor of nasal cavity  ethmoid & sphenoid bones form the roof  hard palate forms floor Figure 22.3c  separates nasal cavity from oral cavity & allows breathing while chewing  paranasal sinuses & nasolacrimal duct – these drain into nasal cavity  THE NOSE  nasal conchae  superior, middle & inferior conchae (turbinates)  project from lateral walls toward septum  meatus - narrow air passage beneath each concha  dimensions & turbulence ensure that most air contacts mucous membranes  clean, warm & moisten air  olfactory epithelium - detects odors  covers small area of roof of nasal fossa, adjacent parts of septum & superior concha  ciliated pseudostratified columnar epithelium  immobile cilia on sensory cells bind odorant molecules NASAL CONCHAE - MRI Septum Turbinate bone Photos © McGraw-Hill Education  NASAL SEPTUM & CONCHAE Nasal septum Nasal cavity Middle nasal Inferior nasal concha concha Photos © McGraw-Hill Education  OLFACTORY EPITHELIUM Olfactory nerves Olfactory bulb Olfactory tract Photos © McGraw-Hill Education  THE NOSE  respiratory epithelium lines rest of nasal cavity except vestibule  ciliated pseudostratified columnar epithelium with goblet cells  cilia are motile  goblet cells secrete mucus & cilia propel mucus posteriorly toward pharynx  extensive venous plexus in epithelium of inferior concha  helps warm incoming air  mucosa can become inflamed  RESPIRATORY MUCOSA Photos © McGraw-Hill Education  PARANASAL SINUSES Ethmoidal Maxillary Frontal Sphenoidal Photos © McGraw-Hill Education  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system√  Describe the anatomy of the component parts of the respiratory system √  Describe the anatomy of the pharynx, larynx and trachea  Describe the arrangement of the lungs and pleura, and bronchial tree  Name the muscles of respiration and describe their roles  THE PHARYNX  muscular funnel extending from nasal choanae to larynx Three regions of pharynx  nasopharynx  posterior to nasal apertures & above soft palate  receives auditory tubes & contains Nasopharynx pharyngeal tonsil  oropharynx  space between soft palate & epiglottis  contains palatine tonsils  laryngopharynx  epiglottis to cricoid cartilage  continuous with muscles of oesophagus Oropharynx Laryngopharynx  THE PHARYNX  nasopharynx passes only air & is lined by pseudostratified columnar epithelium  oropharynx & laryngopharynx transport air, food & liquids & are lined by stratified squamous epithelium  muscles of the pharynx assist in swallowing & speech  THE LARYNX  cartilaginous chamber at junction of respiratory & digestive tracts  primary function is to keep food & liquids out of airway  in some animals it has evolved additional role of phonation - production of sound  THE LARYNX  comprises nine small cartilages, muscles & membranes  unpaired & paired cartilages Unpaired:  epiglottis - guards opening into larynx  thyroid - laryngeal prominence (Adam’s apple)  testosterone stimulates growth, larger in males  cricoid cartilage - connects larynx to trachea, ring-like in structure  THE LARYNX Paired cartilages  arytenoid cartilages - posterior to thyroid cartilage  corniculate cartilages – articulate with arytenoid cartilages  cuneiform cartilages - support soft tissue between arytenoids & epiglottis  Ligaments suspend larynx from hyoid & hold structures in place  thyrohyoid ligament suspends it from hyoid  cricotracheal ligament suspends trachea from larynx  intrinsic ligaments hold laryngeal cartilages together  LARYNX – ANTERIOR VIEW Cricothyroid ligament Thyroid Cricoid Thyrohyoid Epiglottis cartilage cartilage membrane Photos © McGraw-Hill Education  LARYNX – POSTERIOR VIEW Epiglottis Thyroid Cricoid Arytenoid Corniculate Photos © McGraw-Hill Education  LARYNX Photos © McGraw-Hill Education  THE LARYNX: VOCAL CORDS  interior wall of larynx has two folds on each side  extend from thyroid cartilage anteriorly to arytenoid cartilages posteriorly  superior [vestibular] folds  play no role in speech  close the larynx during swallowing  inferior [vocal] folds  produce sound when air passes between them  contain vocal ligaments – vocal cords  covered with stratified squamous epithelium  endure vibration & contact  glottis - vocal cords & opening between them  LARYNX – LATERAL VIEW Epiglottis Vestibular Thyroid Vocal fold fold cartilage Photos © McGraw-Hill Education  ENDOSCOPIC VIEW OF RESPIRATORY TRACT Figure 22.5a Copyright © McGraw-Hill Education. Permission required for reproduction or display. a: © CNRI/Phototake  THE LARYNX: MUSCULATURE  intrinsic muscles control vocal cords  contraction causes corniculate & arytenoid cartilages to pivot  abduct or adduct vocal cords, depending on direction of rotation  produces high-pitched sound when cords are taut  lower-pitched sounds when cords more slack  crude sounds formed into words by actions of pharynx, oral cavity, tongue & lips  ACTION OF MUSCLES ON THE VOCAL CORDS Figure 22.6 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  THE TRACHEA  rigid tube 12 cm long & 2.5 cm in diameter  posterior to sternum & anterior to oesophagus  supported by 16-20 C-shaped rings of hyaline cartilage  reinforce trachea & prevent collapse during inhalation  rings face posteriorly toward esophagus – completed by trachealis muscle  allows oesophagus to expand during swallowing  contracts or relaxes to adjust airflow  TRACHEA Photos © McGraw-Hill Education  TRACHEA: LOW MAGNIFICATION Photos © McGraw-Hill Education Epithelium Submucosa Perichondrium Lamina propria Cartilage  TRACHEA ▪ bifurcates at level of sternal angle [T4] ▪ right & left main bronchi ▪ carina: internal medial ridge in lowermost tracheal cartilage ▪ directs airflow to right & left Carina Photos © McGraw-Hill Education  TRACHEA & PRIMARY BRONCHI Photos © McGraw-Hill Education  MICROANATOMY OF THE TRACHEA  lined by ciliated pseudostratified columnar epithelium  mainly mucus-secreting cells, ciliated cells & stem cells  mucociliary escalator: mechanism for debris removal  mucus traps inhaled particles - cilia drive mucus toward pharynx  middle tracheal layer - connective tissue beneath the tracheal epithelium  lymphatic nodules, mucous & serous glands & tracheal cartilage  adventitia - outermost layer of trachea  fibrous connective tissue that blends with adventitia of other organs of mediastinum  ANATOMY OF LOWER RESPIRATORY TRACT Figure 22.7 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  THE TRACHEAL EPITHELIUM © Prof. P.M. Motta/Univ. “La Sapienza,” Rome/Science Source Figure 22.8 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system√  Describe the anatomy of the component parts of the respiratory system √  Describe the anatomy of the pharynx, larynx and trachea √  Describe the arrangement of the lungs and pleura, and bronchial tree  Name the muscles of respiration and describe their roles  GROSS ANATOMY OF THE LUNGS (a) Anterior view Figure 22.9a Copyright © McGraw-Hill Education. Permission required for reproduction or display.  THE LUNGS  lie within the thoracic cavity  apex projects just above the clavicle  broad concave base rests on diaphragm  costal surface in contact with ribcage  mediastinal surface faces medially towards heart  hilum – region where main bronchus, blood vessels, lymphatics & nerves enter/leave the lung  ‘root’ of the lung  CROSS SECTION THROUGH THE THORACIC CAVITY Figure 22.10 © McGraw-Hill Education/Rebecca Gray, photographer/Don Kincaid, dissections  GROSS ANATOMY OF THE LUNGS (b) Mediastinal surface, right lung Figure 22.9b Copyright © McGraw-Hill Education. Permission required for reproduction or display.  THE LUNGS  Right lung  shorter than left because liver on right  three lobes – upper [superior], middle & lower [inferior]  lobes separated by horizontal & oblique fissure  Left lung  two lobes - superior & inferior separated by oblique fissure  indentation caused by heart - cardiac impression  THE PLEURAE  connective tissue membranes with serous epithelial lining  line thoracic cavity & reflect onto & line the lungs  parietal pleura - adheres to mediastinum, inner surface of rib cage, & upper surface of diaphragm  visceral pleura – lines surfaces of lungs  pleural cavity - potential space between parietal and visceral pleurae  cavity normally ‘empty’ - film of pleural fluid Functions of pleurae & pleural fluid  reduce friction  create pressure gradient  lower pressure than atmospheric pressure - assists lung inflation  compartmentalisation - prevent spread of infection  PLEURA Photos © McGraw-Hill Education Parietal pleura Pleural cavity Visceral pleura PLEURA  PARIETAL & VISCERAL PLEURAE Photos © McGraw-Hill Education  PULMONARY CIRCULATION Pulmonary trunk Left pulmonary artery Left lung Left pulmonary veins Left atrium Right pulmonary veins Photos © McGraw-Hill Education  THE BRONCHIAL TREE  branching system of air tubes in each lung  from main bronchus to ± 65,000 terminal bronchioles  main (primary) bronchi - supported by C-shaped hyaline cartilage rings  enter lungs at hilum  right main bronchus is 2-3 cm in length  slightly wider & more vertical than left  aspirated (inhaled) foreign objects lodge in right main bronchus more often than in left  left main bronchus is 5 cm long  slightly narrower & more horizontal than the right  THE BRONCHIAL TREE  main bronchi divide into lobar bronchi  lobar (secondary) bronchi - crescent-shaped cartilage plates  three lobar bronchi in right lung - superior, middle & inferior  two lobar bronchi in left lung - superior & inferior  lobar bronchi divide into segmental (tertiary) bronchi - supported by crescent-shaped cartilage plates  10 in the right lung, 8 in the left lung  bronchopulmonary segment: functionally independent unit of the lung tissue  THE BRONCHIAL TREE  all bronchi are lined with ciliated pseudostratified columnar epithelium  cells grow shorter & epithelium thinner as divisions continue  lamina propria has abundant mucous glands & lymphocyte nodules (mucosa- associated lymphoid tissue, MALT)  positioned to intercept inhaled pathogens  all divisions of bronchial tree have large amount of elastic connective tissue  contributes to recoil that expels air from lungs  THE BRONCHIAL TREE  mucosa has a well-developed layer of smooth muscle  muscle contracts or relaxes to constrict or dilate airway, regulating airflow  pulmonary artery branches closely follow bronchial tree on route to alveoli  bronchial arteries supply bronchial tree with systemic blood  arise from the aorta  THE BRONCHIAL TREE  bronchioles  1 mm or less in diameter  ciliated cuboidal epithelium  well-developed layer of smooth muscle  divide into 50-80 terminal bronchioles  final branches of conducting zone  measure ±0.5 mm in diameter  no mucous glands or goblet cells  cilia move mucus out Figure 22.12a  each terminal bronchiole gives rise to 2 or more respiratory bronchioles  THE BRONCHIAL TREE  respiratory bronchioles  have alveoli budding from their walls  considered the start of the respiratory zone since alveoli participate in gas exchange  divide into 2-10 alveolar ducts  end in alveolar sacs: clusters of alveoli arrayed around a central space called the atrium  LUNG TISSUE Conducting bronchiole Pulmonary artery branch Photos © McGraw-Hill Education Alveolar duct Alveolar sacs Alveolar sac  MICROANATOMY OF THE LUNG Figure 22.11 a: © Microscape/SPL/Science Source; b: © Biophoto Associates/Science Source  ALVEOLI  150 million alveoli in each lung  70 m2 of surface for gas exchange Cells of the alveolus  Type I alveolar cells  squamous, allow for rapid gas diffusion between alveolus & bloodstream  cover 95% of alveolus surface area  Type II alveolar cells  round to cuboidal cells that cover remaining 5% of alveolar surface  repair alveolar epithelium when squamous (Type I) cells are damaged  secrete pulmonary surfactant - phospholipids & proteins that coat alveoli & prevent them from collapsing during exhalation RESPIRATORY DIVISION Photos © McGraw-Hill Education  ALVEOLI  alveolar macrophages (dust cells)  most numerous of all cells in the lung  keep alveoli free from debris by phagocytizing dust particles  100 million dust cells die each day - swallowed & digested  ALVEOLI  each alveolus surrounded by capillaries from pulmonary artery  respiratory membrane - thin barrier between alveolar air & blood Respiratory membrane consists of:  squamous alveolar cells  endothelial cells of blood capillary  shared basement membrane Figure 22.12b,c Copyright © McGraw-Hill Education. Permission required for reproduction or display.  ALVEOLI  structure key to preventing fluid from accumulating in alveoli  gases diffuse too slowly through liquid to sufficiently aerate the blood  alveoli kept dry by absorption of excess liquid by blood capillaries  lungs have more extensive lymphatic drainage than any other organ  low capillary blood pressure prevents rupture of delicate respiratory membrane  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system√  Describe the anatomy of the component parts of the respiratory system √  Describe the anatomy of the pharynx, larynx and trachea √  Describe the arrangement of the lungs and pleura, and bronchial tree √  Name the muscles of respiration and describe their roles MUSCLES OF RESPIRATION Photos © McGraw-Hill Education  RESPIRATORY MUSCLES  diaphragm  prime mover of respiration  contraction flattens diaphragm, enlarging thoracic cavity & pulling air into lungs  relaxation allows diaphragm to bulge upward again, compressing lungs & expelling air  accounts for two-thirds of airflow  DIAPHRAGM Photos © McGraw-Hill Education  DIAPHRAGM Photos © McGraw-Hill Education  INTERCOSTAL & SCALENE MUSCLES  Internal & external intercostal muscles  synergists to diaphragm  located between ribs  stiffen thoracic cage during respiration  prevent thorax from collapsing inward when diaphragm descends  contribute to enlargement and contraction of thoracic cage  Scalene muscles  synergist to diaphragm  fix or elevate Ribs 1 & 2  EXTERNAL INTERCOSTAL MUSCLES Photos © McGraw-Hill Education  INTERNAL INTERCOSTAL MUSCLES Photos © McGraw-Hill Education SCALENE MUSCLES Photos © McGraw-Hill Education  ACCESSORY MUSCLES OF RESPIRATION  accessory muscles of respiration act mainly in forced respiration  greatly increase thoracic volume  forced inspiration  erector spinae  sternocleidomastoid  pectoralis major & pectoralis minor  serratus anterior muscles  scalene muscles  ERECTOR SPINAE insertion origin Photos © McGraw-Hill Education  STERNOCLEIDOMASTOID insertion origin Photos © McGraw-Hill Education  PECTORALIS MAJOR Photos © McGraw-Hill Education  PECTORALIS MINOR Photos © McGraw-Hill Education  RESPIRATORY MUSCLES  normal quiet expiration  energy-saving passive process achieved by elasticity of lungs & thoracic cage  as muscles relax, structures recoil to original shape & original (smaller) size of thoracic cavity - results in airflow out of the lungs  forced expiration  rectus abdominis, internal intercostal muscles & other lumbar, abdominal & pelvic muscles  greatly increased abdominal pressure pushes viscera up against diaphragm increasing thoracic pressure, forcing air out  important for “abdominal breathing”  LEARNING OUTCOMES By the end of this lecture you should be able to:  Outline the functions of the respiratory system√  Describe the anatomy of the component parts of the respiratory system √  Describe the anatomy of the pharynx, larynx and trachea √  Describe the arrangement of the lungs, pleura, and bronchial tree √  Name the muscles of respiration and describe their roles √  NEXT LECTURE RESPIRATORY SYSTEM 2