2The Respiratory System Functions to supply the body with O2 and remove CO2There are actually 4 distinct processes:Ventilation – Movement of air into & out of the lungsExternal Respiration – Gas exchange between blood and air-filled chambers of the lungsTransport of Gases – Accomplished by Cardiovascular systemInternal Respiration – Gas exchange between systemic blood and the tissue cells
4Organs include: nose, nasal cavity, pharynx, trachea, bronchi, bronchioles, and the alveoli. Divided into Respiratory and Conducting Zones.Gas exchange with the blood occurs in the respiratory zones. It does NOT occur in the conducting zones.The conducting zones transport, cleanse, warm and humidify the incoming air.Functional Anatomy
7The Nose Only externally visible part of the respiratory system. Functions include:Providing an airway for respiration- ConductMoistening and warming air- Warm and HumidifyFiltering inspired air- ProtectServing as a resonating center for speechHousing the olfactory receptors.
8Skeletal Framework of External Nose Fashioned by the:Nasal and frontal bones superiorlyMaxillary bones laterallyPlates of hyaline cartilage (lateral, septal, and alar cartilages) inferiorly.
9Nasal Cavity Lies in and posterior to the external nose Divided by a midline nasal septum – formed anteriorly by septal cartilage and posteriorly by the vomer bone and perpendicular plate of the ethmoid bone.Continuous with the nasopharynx via the internal nares.Roof is formed by the sphenoid & ethmoid bones.
10Nasal Cavity Floor is formed by the palate. Hard palate contains portions of the maxillary and palatine bones.Soft palate lacks bone, a flexible mass of collagen fibers
11Nasal Cavity Lined by 2 types of epithelium. Slit-like superior region is lined by olfactory epithelium.What does it do?The rest is line by respiratory epithelium (pseudostratified ciliated columnar with goblet cells)It rests on a connective tissue layer richly supplied with mucous and serous glands.
13Mucus vs SputumSputum is matter that is coughed up from the respiratory tract, such as mucus or phlegm, mixed with saliva and then expectorated from the mouth.Mucus is a slippery secretion of the lining of the mucous membranes in the body.. Mucus is produced by goblet cells in the mucous membranes that cover the surfaces of the membranes.
14MucusMucus is produced by goblet cells in the mucous membranes that cover the surfaces of the membranes. It is made up of mucins and inorganic salts suspended in water. Contains Lysosomes.Phlegm is a type of mucus that is restricted to the respiratory tract, while the term mucus refers to secretions of the nasal passages as well.
15Mucus High H2O content of mucus humidifies inward air Ciliary current moves mucus to pharynx for swallowing.Cold temps disable these cilia; runny noseRich plexuses of capillaries and veins underlie the nasal epithelium and warm incoming air
16Nasal CavityProtruding medially from each lateral wall of the nasal cavity are 3 scroll-like, mucosa-covered projections: the superior, middle, and inferior conchae or turbinatesThey increase the mucosal surface area exposed to airThe groove inferior to each concha is a meatus.Nasal cavity is surrounded by a ring of paranasal sinuses located in the frontal, sphenoid, ethmoid and maxillary bones.
19Anatomy and Physiology Revealed CUT AWAY OF UPPER AIRWAY
20How Does this System function.. Air first enters the nares into a slightly dilated area called the vestibule. The vestibule is lined with hairs called vibrissae, a protective mechanism against foreign particles. PROTECTThe anterior 1/3rd of the nasal cavity is lined with stratified squamous epithelium, posterior 2/3rd lined with pseudostratified ciliated columnar epithelium
21How Does this System function.. Air then travels through the turbinates (conchae) where the function is to separate inspired air into separate streams.This allows for an increase of surface area.This increased surface area increases the temperature of the air and adds moisture.WARM and HUMIDIFY
22Oral Cavity Accessory Respiratory Passage Lined with stratified squamous epitheliumAir enters the vestibule (small outer portion between gums and lips) and large opening that extends to the back of the oropharynxRoof of the oral cavityHard PalateSoft PalateUvula
23Oral CavitySoft palate rises, shutting off the passage between the nasal and oral cavityLevator veli palatinum muscle draws up and backPalatopharyngeal muscle draws down and forwardPalantine ArchesPalatopharyngeal ArchPalatoglossal ArchContains the tonsils, adenoids and lymph tissue; Front line protection
25Pharynx Funnel-shaped. Connects the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly3 regions. From superior to inferior:NasopharynxOropharynxLaryngopharynx
26NasopharynxPosterior portion of the nasal cavity, superior portion of the soft palate, contains adenoids.Only an air passage. During swallowing, the soft palate and its uvula move superiorly and close it off.Lined by pseudostratified ciliated columnar epithelium.High on its posterior wall is the pharyngeal tonsil (adenoids) which traps entering pathogens.The eustachian tubes open into its lateral walls. They connect the middle ear to the nasal cavity; pressure release function
27Oropharynx Lies posterior to the oral cavity Extends from the soft palate to the base of the tongue – hyoid boneLined by stratified squamous epitheliumPaired palatine tonsils lie in the lateral walls while the lingual tonsil covers the base of the tongue
28Laryngopharynx Also called “hypopharynx” Extends from the base of the tongue to the entrance of the esophagus.Common passage for both food and airLined by stratified squamous epithelium
30LarynxSuperiorly attached to the hyoid bone and opens into the laryngopharynx.Inferiorly, it’s continuous with the tracheaMain tasks are:Provision of a patent airway for air and food.Routing of air and food to proper pathways.Voice production.
32LarynxConsists of an intricate arrangement of 9 cartilages connected by membranes and ligaments.3 single cartilagesEpiglottis, Cricoid, and Thyroid3 paired cartilagesCuneiform, corniculate and arytenoid
33The large, shield-shaped thyroid cartilage is formed by the fusion of 2 cartilage plates. The fusion point is the laryngeal prominence (adam’s apple). The ridge is called the thyroid notchInferior to the thyroid cartilage is the cricoid cartilage. Signet ring shape with increased size to the posterior. Cricoid membrane is the site for emergent airways.The first “C” shaped tracheal ring lies below the cricoid cartilage3 pairs of small cartilages, the arytenoid, cuneiform, & corniculate cartilages form part of the lateral & posterior walls of the larynxThe important arytenoids anchor the vocal cords
34The 9th cartilage (epiglottis) is spoon-shaped & composed of elastic cartilage. Epiglottis is covered almost entirely by a taste-bud containing mucosa.During swallowing, the larynx is pulled superiorly and the epiglottis tips to cover the laryngeal inlet.If anything other than air enters the larynx – a cough/gag reflex is initiated by the sensory nerve; glossopharyngeal and the motor nerve; vagus.
38Epiglottis and Vallecula The space between the base of the tongue and the epiglottis is called the valleculaThis is an important landmark in the airwayWhile intubating, if using a macintosh blade the tip of the blade slides into the vallecula causing the epiglottis to lift. If using a miller blade, the epiglottis is directly lifted up to allow access to the airway.
41Lying under the laryngeal mucosa on each side are the vocal ligaments These ligaments (made mostly of elastic fibers) form the core of mucosal folds called the vocal folds or true vocal cordsVocal cords vibrate, producing sounds as air rushes up from the lungs.Superior to the true vocal cords is a similar pair of mucosal folds called the vestibular folds or false vocal cords.The superior portion of the larynx is lined by stratified squamous epithelium, while below the vocal cords, it’s a pseudostratifed ciliated columnar epithelium.
42The medial opening between them thru which the air passes is the rima glottidis or GLOTTIS. In an adult, the glottis is the narrowest point of the adult larynx.In an infant and small child, the cricoid cartilage is the narrowest point.Subglottic swelling in an infant or small child, due to infection or trauma can cause stridor during inspiration
46The larynx is closed by the epiglottis during swallowing. In addition to opening and closing the glottis for speech, the vocal folds can act as a sphincter during conditions such as coughing, sneezing or straining
50The Arytenoid cartilage is shaped like a pyramid which rests on the posterior portion of the cricoid cartilageAt the base of the arytenoid cartilage a projection called the vocal process, the vocal ligaments attach vocal process and the thyroid cartilageThe cuneiform and corniculate are accessory cartilages at the superior portion of the arytenoids
55Laryngeal Musculature ExtrinsicInfrahyoid (below the hyoid)Pulls the larynx and hyoid down the neckSternohyoid, sternothyroid, throhyoid and omohyoidSuprahyoid (above the hyoid)Pulls the hyoid bone forwards, upwards and backwardsStylohyoid, mylohyoid, digastric, geniohyoid and stylopharyngeus
56Laryngeal Musculature IntrinsicThey all deal with the arytenoid cartilage and vocal cord movement.Posterior cricoarytenoid, lateral cricoarytenoid, transverse, thyroarytenoid and cricothyroid.
58Ventilatory Function of the Larynx Ensures a free flow of air to and from the lungsDuring inspiration, vocal cords move apart; abduct, and widens glottis for improved airflowForced expiration against a closed glottis, “Valsalva’s maneuver” causes massive adduction preventing air from escaping during cough, vomiting, urination, defecation and parturition.Forced inspiration against a closed glottis, “Mueller maneuver” --- missed sputum bowl question!
60The Lower AirwaysAfter passing through the larynx, inspired air enters the Tracheobronchial TreeThe traceobronchial tree consists of a series of branching airways called “orders” or “generations”It is believed that there are 28 generations or orders of the tracheobroncial tree
63Tracheobronchial Tree The tracheobronchial tree is divided into two general zonesConducting Zone or Cartilaginous AirwaysNo Gas Exchange occurs in this zoneRespiratory Zone or Non Cartilaginous AirwaysThe site of Gas ExchangeThere a transition zone where no cartilage surrounds the airway, yet no gas exchange occurs
64Histology of the Tracheobroncial Tree Three layersEpithelial LiningLamina propriaCartilaginous Layer
66Epithelial Lining Psuedostratified ciliated columnar epithelium Numerous Mucous glands interspersedAnchored to a basement membrane that contains basal cells (reserve cells and replenish mucus glands and ciliated cells)200 cilia per cellCells move from columnar to cuboidal and cilia disappear as you move down the tree
68Epithelial LiningA mucus layer, or “mucous blanket” covers the epithelial lining of the tracheobronchial tree.Produced by goblet cells and submucosal /bronchial glandsGoblet cells are located between the epithelial cellsSubmucosal glands extend into the lamina propria and are innervated by the parasympathetic nervous system.Composed of 95% water and the remainder is carbohydrates, glyocproteins, lipids, DNA, cellular debris and foreign particles.
70Mucous Blanket The body produces about 100ml of secretions per day. The viscosity of the secretions increase as you move from the lining to the lumen.Two distinct layersSOL Layer, adjacent to the epithelial liningLess viscousGEL Layer, adjacent to the inner lumenMore viscous
71Mucous BlanketCilia move in a wavelike fashion, beating 1500 times per minute through the less viscous sol layer and strike the inner layer of the more viscous gel layer.This action propels the mucus layer, along with any foreign particles attached to the “sticky” gel layer towards the larynx at 2cm per minuteThe cough mechanism moves the secretions above the larynx and into the oropharynx
72Mucous BlanketThis cleansing process is called Mucociliary Transport or the Mucociliary EscalatorWhat slows the rate down:Cigarette smoke,DehydrationPositive Pressure VentilationEndotracheal SuctioningHigh FiO2HypoxiaAtmospheric pollutantsGeneral anestheticsParasympatholytics
73Lamina Propria This is a submucosal layer Loose fibrous tissue containing blood vessels, lymphatic vessels, vagus nerve innervationTwo sets of smooth muscle that wrap in spirals both clockwise and counterclockwiseThe smooth muscle fibers extend to the alveolar ductsThe lamina propria is surrounded by a thin connective tissue layer called the peribronchial sheath
75Lamina Propria Mast Cells are located in the lamina propria Their cytoplasm is loaded with granules containing mediators of inflammation.Histamine, heparin, SRS-A (slow reacting substance of anaphylaxis), PAF (platelet activating factor), ECF-A (eosinophilic chemotaxic factor of anaphylaxis)Their surface is coated with a variety of receptors which, when engaged by the appropriate antigen trigger exocytosis of the granules.Destablization of mast cells in the lungs canbe extremely dangerous, and is what we see in patients with an allergic asthmatic episode
77Cartilaginous Layer Outermost layer of the tracheobronchial tree This layer progressively diminishes in size as the airway extend into the lungs.Cartilage is absent in bronchioles less than 1 mm in diameter
80Trachea In the adult, it is 11 to 13 cm long, 1.5 – 2.5 cm in diameter Descends from the cricoid to the 2nd costal cartilageANGLE OF LOUISIt bifurcates, divides into the right and left main stem bronchi, this division is called the carina
81There are C-shaped rings of cartilage that support the trachea, keeping the airway patent and prevent its collapse.The open posterior parts of the rings are adjacent to the the esophagus and are connected by fibers of the trachealis muscle, which is involved in coughing..
83Main Stem and Lobar Bronchi The Main Stem Bronchi are the 1st generation of the tracheobronchial treeThe right main stem bronchus branches off the trachea at a 25 degree angle, the left bronchus forms a 40 – 60 degree angleThe right bronchus is wider, more vertical, and 5 cm shorter than the left.
86Main Stem and Lobar Bronchi Main Stem bronchi are supported by ‘C’ shaped cartilageEach bronchus runs obliquely into the mediastinum before plunging into the medial depression (hilus) of the lung on its own side.Inside the lungs, the main stem or primary bronchi divide into lobar or secondary bronchi, 3 on the right and 2 on the left, each of which supplies one lung lobe.3 lobes on the right, 2 lobes on the left (room for heart)
90Bronchi and Subdivisions The lobar bronchi become segmental; third generation.10 in the right lung and 8 in the left lungSubsegmental bronchi range in diameter from 1 – 4 mm. Peribronchial sheaths containing nerves, vessels and lymphatic tissue surround the subsegmental bronchi down to the 1 mmThese are the 4th – 9th generation.
91Non Cartilaginous Airways BronchiolesWhen the diameter decreases to less than 1mm,they are no longer surrounded by a connective sheath,cartilage is absent, rigidity is absent-airway patency can be compromisedA muscle sheath surrounding the bronchiolesColumnar epithelial becomes cuboidalGenerations
92Terminal Bronchioles 16th – 19th Generation; Diameter is about 0.5 mmCilia and mucous glands progressively disappearEpithelium is cuboidal and thinChannels called “Canals of Lambert” appearConnect the surface of terminal bronchioles to adjacent alveoliThought to aid in collateral ventilation in individuals with respiratory disorders such as COPDPresence of Clara CellsFunction unknown, they have a thick protoplasmic extensions that bulge into the bronchial lumen - perhaps they secrete an enzyme that detoxifies inhaled substances16th – 19th Generation;TERMINAL- END: Structures beyond this point are not part of the Tracheobronchial tree.Structures distal to this point are the sites of gas exchange; referred to as the Respiratory Zone
96As conducting tubes become smaller… The cartilage support changes. It goes from rings in the trachea to irregular plates in the bronchi to none in the bronchioles.Why?The epithelium changes. It goes from respiratory to simple columnar to simple cuboidal.The number of cilia and goblet cells present decrease.The amount of smooth muscle increases.
97Gas FlowOnce in the Respiratory Zone, the cross sectional area of the lung increases exponentially.Forward motion of gas flow stops-no bulk flow, no laminar flowThe movement of gas becomes molecular
100Bronchial Blood Supply Tracheobronchial tree requires blood flowArteries follow the tracheobronchial tree as far as the terminal bronchiolesBeyond the terminal bronchioles, this vascular system merges with the pulmonary vascular system.RA – RV– PA - Lungs – LA – LV –Aorta - Systemic
101Bronchial Blood Supply Approximately 1% of Cardiac Output serves the tracheobronchial tree.Of that 1%, 1/3rd of it returns to the Right Atrium as unoxygenated venous blood.The vessels responsible for this returnAzygosHemiazygosIntercostal veinsRA – RV – PA - Lungs – LA – LV –Aorta - Systemic
102via bronchopulmonary anastomoses The remaining 2/3rd of the bronchial venous blood drains into the pulmonary circulation, into the pulmonary arteries and capillariesvia bronchopulmonary anastomosesThis results in a mixture of low oxygenated and high carbon dioxide blood from the tracheobronchial tree with highly oxygenated low carbon dioxide blood returning to the left atrium for systemic circulationRA – RV – PA - Lungs – LA – LV –Aorta – Systemic2/3rd of blood returning from bronchical circulationThis is an example of an anatomical shunt, and called venous admixture
103The Respiratory ZoneDistal to the terminal bronchioles are the functional units of gas exchangeConsists of:3 generations of Respiratory Bronchioles3 generations of Alveolar DuctsEnding in grapelike clusters called Alveolar SacsThese units, Respiratory Bronchioles, Ducts and Alveoli are called a primary lobule or acinus, or terminal respiratory unit or lung parenchyma or functional units
105Alveoli Composed of smooth muscle fiber Approximately 300 million alveoli which are 90% covered with capillaries.The surface area of the alveoli is 70 square meter, the surface of a tennis courtEach primary lobule, 130,000 each stem from a single terminal bronchiole and contains about 2000 alveoli
107Alveolar Epithelium Alveoli are consist of 3 cell types: Type I cells; Squamous EpitheliumCover 95% of the alveolar surface0.1 – 0.5 micrometers thickMajor site of gas exchangeType II cells; Granular pneumocytesHave microvilliCuboidal in shapeProduce pulmonary surfactantForm the remaining 5% of the alveolar surfaceType III cells; Alveolar macrophagesMigrate through the blood stream and are embedded in the extracellular lining of the alveoli
109Pores of Kohn Pores of Kohn Small holes in the alveolar wall or interalveolar septaAllow gas to move between alveoliFormed byShedding of cells – desquamationNormal degeneration due to ageMovement/detachment of macrophages
110Scattered among the Type I’s are Type II cells which secrete surfactant. Pores of Kohn connect adjacent alveoli.Alveolar macrophages (dust cells) crawl along the internal alveolar surfaces
111InterstitiumSurrounds, supports and shapes the alveolar capillary clustersGel like substance of hyaluronic acid molecules bound together by a network of collagen fibersTwo compartmentsTight Space; the area between the alveolar epithelium and the endothelium of the pulmonary capillaries-Site of gas exchangeLoose Space: the area the surround the bronchioles, respiratory bronchioles, alveolar ducts and sacs. Lymphatic vessels and neural fibers are in this area
117Pulmonary Vascular System ArteriesArteriolesCapillariesVenulesVeins
118Pulmonary Arteries Three Layer Tunica Intima; inner layerEndothelium and a thin layer of connective tissueTunica Media; middle layerThickest layer of the vesselElastic connective tissue in large arteries, smooth muscles in smaller and medium arteriesTunica Adventitia: outer layerConnective tissueContains small vessels that nourish all layersStiff vessels, capable of carrying blood under high pressures.
119Arterioles Endothelial layer Elastic layer Smooth muscle fibers Called “resistance vessels” due to the ability of the smooth muscles to regulate the blood flow
120Capillaries Surround 90% of the alveoli Composed of endothelial layer; single layer of squamous epithelial cellsEssentially an extension of the inner lining of the larger vesselsThis is where gas exchange occursSome prostaglandins are produced here, some biological substances are destroyed here
121Veins and Venules3 Layers, same as arteries, 2 layers in the smaller veins-no tunica adventitiaMiddle layer is poorly developed and contain less smooth muscle and elastic tissuesDue to less elastic and smooth muscle tissue, veins can hold a greater volume of blood with little pressure changes. Because of this, veins are called “capacitance vessels”Veins return to the heart in a more direct route out of the lungs
122The Lymphatic SystemFunction is to remove excess fluid and protein that leak out of the capillariesLocated in a dense connective tissue sheath around the bronchioles, also in the loose space of the interstitiumMore lymphatic channels located on the left side, increased incidence of right sided pleural effusions due to less drainageLike veins, they have one way valves/flapsBronchopulmonary lymph nodes, end of the line, are located outside the lung parenchymaNo lymph vessels in the alveoli, they are located immediately adjacent to the alveoli calledjuxta-alveolar lymphatics
124Neural Control of the Lungs Controlled by the autonomic nervous systemRegulates involuntary vital functionsCardiac musclesSmooth musclesGlandsTwo divisionsSympatheticParasympathetic
125Neural Control of the Lungs SympatheticAccelerates heart rateConstricts blood vesselsRelaxes bronchial smooth musclesRaises blood pressureParasympatheticSlows heart rateConstricts bronchial smooth musclesIncreases intestinal peristalsis and gland activity
126Neural Control of the Lungs Sympathetic neural transmittersEpinephrineNorepinehrineThese agents stimulate theBeta 2 receptors in the bronchial smooth muscles; causing airway muscle relaxationAlpha receptors in the arteriole smooth muscles, causing the pulmonary vascular system to contrict
127Neural Control of the Lungs Parasympathetic neural transmittersAcetylcholineCauses constriction of the bronchial smooth musclesInactivity of either portion allows the other one to dominate the bronchial smooth musclesThere must be careful attention to the role of pharmacological agentsBeta blockers- causes parasympathetic to dominateAtropine-a parasympathetic blocker allows sympathetic to dominate
129Lung Gross AnatomyOccupies all of the thoracic cavity except the mediastinum.Each lung is within its own pleural cavityAnterior, lateral, and posterior surfaces are costal, adjacent to ribsRises above the clavicle to the level of the 1st ribThe concave bases sit on the diaphragm.The mediastinal border is concave to heart and the other mediastinal structureThe hilum is at the center of the mediastinal border, and is where the main stem bronchi, blood and lymph vessels, and nerves enter and exit the lungs
134Lung Gross AnatomyThe right lung is larger and heavier than the left. The Right lung has 3 lobes; upper, middle, and lowerThe lobes are divided by theoblique fissure which divides the upper and middle lobe from the lower lobeHorizontal fissure, divides the upper from the lower lobe..
135Lung Gross AnatomyThe left lung is smaller than the right, contains 2 lobes; upper and a lower lobe and has an indentation (cardiac notch) where the heart sits.The lobes are divided by the oblique fissure
136Lung SegmentsAll Lobes are further divided into bronchopulmonary segments10 on the right8 on the leftCareful with the numbering systems!
137MediastinumA cavity that contains the organs and tissues in the center of the thoracic cage between the right and left lungBordered anteriorly by the sternum, and posteriorly by the vertabraeContains the trachea, heart, the great vessels the major vessels that enter and exit the heart, the esophagus, thymus gland, lymph nodes, and nerves
139The Pleural Membranes Two moist, slick surfaced membranes Parietal pleura covers the thoracic wall, superior diaphragm and lateral portion of the mediastinumVisceral pleura firmly attached and covers the external lung surface, extends into the interlobar fissuresThe potential space between visceral and parietal pleurae is called the pleural cavityThe two membranes are held together by a thin film of serous fluid. The fluid allows the membranes to glide over each other during inspiration and exhalationThe pleural membranes hold the lung tissue to the inner surface of the thorax and diaphragm, allowing for lung expansion during inspiration
141Because the lungs have a natural tendency to collapse and the thorax has a natural tendency to expand, a negative pressure normally exists between these two layers. Should air enter this space, the pleural membranes would separate causing a condition known as a pneumothorax
143The Diaphragm The diaphragm is the major muscle of inspiration Dome-shaped musculofibrous partition located between the thoracic cavity and the abdominal cavityTwo separate muscles; the right and left hemidiaphragm, joined at midline by the central tendonPierced by the esophagus, aorta, nerves and the inferior vena cavaInnervated mainly by the phrenic nerve, the lower thoracic nerves contribute to some motor innervation
145InspirationWhen the diaphragm is stimulated to contract, it moves downward and the lower ribs move upward and outwardThis increases the thoracic volumeWhich causes the lung volume to increaseThe increased lung volume causes lung pressure; intrapleural and intra alveolar to decreaseAs a result, gas from the atmosphere flows into the lungs
149During expiration, the diaphragm relaxes and moves upward into the thoracic cavity This increases the intrapleural and intra-alveolar pressures and causes gas to flow out of the lungsQuiet expiration is a passive process that is due to the elasticity of the lungs.Forced expiration is an active process due to contraction of oblique and transverse abdominus muscles, internal intercostals, and the latissimus dorsi.Expiration