1 Chapter 23 - Part 1 Lecture OutlineSee separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.

2 The Respiratory SystemRespiration is gas exchange: O2 for CO2 Occurs between atmosphere and body cells Cells need O2 for aerobic ATP production and need to dispose of CO2 that process produces The respiratory system provides the means for gas exchange Consists of respiratory passageways in head, neck, and trunk, and the lungs

3 23.1 Introduction to the Respiratory SystemState the functions of the respiratory system. Distinguish between the structural organization and the functional organization of the respiratory system. Describe the structure of the mucosa that lines the respiratory tract and the structural changes observed along its length. Explain the function of mucus produced by the mucosa. Learning Objectives:

4 23.1a General Functions of the Respiratory SystemAir passageway Air moves from atmosphere to alveoli as we breathe in Air moves from lungs to atmosphere as we breathe out Site for oxygen and carbon dioxide exchange (alveoli and pulmonary capillaries) Oxygen diffuses from alveoli into blood Carbon dioxide diffuses from blood into alveoli Odor detection Olfactory receptors in superior nasal cavity Sensory input is relayed to the brain

5 23.1a General Functions of the Respiratory SystemSound production Air moves across vocal cords of the larynx (voice box) Vocal cords vibrate, producing sound Sounds resonate in the upper respiratory structures Rate and depth of breathing influence Blood levels of O2, CO2, H+ Venous return of blood; lymphatic return of fluid to blood

6 23.1b General Organization of the Respiratory SystemStructural organization Upper respiratory tract Larynx and above Lower respiratory tract Trachea and below Functional organization The conducting zone transports air Nose to terminal bronchioles The respiratory zone participates in gas exchange Respiratory bronchioles to alveoli

7 General Anatomy of the Respiratory SystemFigure 23.1

8 23.1c Respiratory Mucosa Mucosa = mucous membrane: respiratory liningEpithelium resting on a basement membrane Underlying lamina propria made of areolar connective tissue Respiratory epithelium Becomes thinner from the nose to the alveoli Starts out as pseudostratified ciliated columnar Changes to simple ciliated columnar Changes to simple cuboidal Changes to simple squamous Exceptions: stratified squamous found in high abrasion areas of pharynx and on and around vocal cords

9 Respiratory Mucosa Figure 23.2a

10 Respiratory Mucosa Figure 23.2b

11 23.1c Respiratory Mucosa Mucous secretions Produced from secretions ofGoblet cells of epithelial lining Mucous and serous glands of the lamina propria Contain mucin protein Increases mucus viscosity and serves to trap dust, dirt, pollen, etc. 1 to 7 tablespoons produced daily Contains defenses against microbes Lysozyme (antibacterial enzyme) Defensins (antibacterial proteins) Immunoglobulin A (antibody) Called sputum when coughed up with saliva and trapped substances

12 What did you learn? What is the difference between the conducting and respiratory zones? How does the respiratory mucosa change along its course? Is the trachea in the upper or lower respiratory tract? What is sputum?

13 23.2 Upper Respiratory TractDescribe the structure and function of the nose. Provide a general description of the structure and function of the nasal cavity. Describe the structure and function of the four paired paranasal sinuses. Compare the three regions of the pharynx, and describe their associated structures. Learning Objectives:

14 23.2a Nose and Nasal Cavity Nose: first conducting structure for inhaled air Formed by bone, hyaline cartilage, dense irregular connective tissue, and skin Bridge of nose formed by paired nasal bones One pair of lateral cartilages and two pairs of alar cartilages Flared part of nostrils (nares) made of dense irregular connective tissue

15 Upper Respiratory TractFigure 23.3a,b

16 23.2a Nose and Nasal Cavity Nasal cavity: from nostrils to choanaeAn oblong-shaped internal space Choanae (posterior nasal apertures) lead to pharynx Floor formed by palate Roof made of nasal, frontal, ethmoid, and sphenoid bones plus some cartilage Nasal septum divides left and right sides Anterior part is septal nasal cartilage Posterior part is bony perpendicular plate of ethmoid plate and vomer bone

17 23.2a Nose and Nasal Cavity The nasal conchaeThree paired, bony projections on lateral walls of nasal cavity Superior, middle, and inferior conchae Also called turbinate bones Produce turbulence in inhaled air Partition the nasal cavity into separate passages Each passage called a nasal meatus Each meatus immediately inferior to its corresponding concha

18 23.2a Nose and Nasal Cavity Nasal cavity partsNasal vestibule: just inside nostrils Lined by skin and particle-trapping hairs called vibrissae Olfactory region Superior part of nasal cavity containing olfactory epithelium Airborne molecules stimulate receptors for odor detection Respiratory region Lined by pseudostratified ciliated columnar epithelium Has an extensive vascular network Nosebleeds (epistaxis) common due to large numbers of superficial vessels

19 Upper Respiratory TractFigure 23.3c,d

20 23.2a Nose and Nasal Cavity Nasolacrimal ductsDrain lacrimal secretions from eye surfaces to nasal cavity Nasal cavity warms, cleanses, and humidifies Air is warmed by extensive blood vessels Mucus traps dust, microbes, and foreign material Cilia sweep mucous toward the pharynx to be swallowed Moist environment humidifies Air turbulence created by conchae enhances all three processes

21 Clinical View: Runny NoseRhinorrhea (runny nose) occurs as a result of Increased production of mucus (allergies, virus) Increased secretions from lacrimal glands draining into the nasal cavity (crying) Exposure to cold air (water condensation + less effective cilia)

22 23.2b Paranasal Sinuses Paranasal sinuses: spaces within skull bonesNamed for specific bone in which they are housed All connected by ducts to nasal cavity From superior to inferior Frontal sinuses Ethmoidal sinuses Sphenoidal sinuses posterior to ethmoidal sinuses Maxillary sinuses

23 23.2b Paranasal Sinuses Lined by pseudostratified ciliated columnar epithelium Mucus swept into pharynx and swallowed Figure 23.4

24 Clinical View: Sinus Infections and Sinus HeadachesRespiratory infection or allergy can cause inflammation of the ducts that drain from the paranasal sinuses. Drainage of mucus decreases and accumulates in the sinuses. Germs can grow in the accumulated mucous, causing a sinus infection. Inflamed and blocked sinuses and pressure changes can cause sinus headaches.

25 23.2c Pharynx Pharynx (throat)Funnel-shaped passageway posterior to nasal cavity, oral cavity, and larynx Lateral walls composed of skeletal muscles Partitioned into Nasopharynx Oropharynx Laryngopharynx Figure 23.5a

26 23.2c Pharynx Nasopharynx: most superior part of pharynxPosterior to nasal cavity, superior to soft palate Lined by pseudostratified ciliated columnar epithelium An air passage—not for food Soft palate elevates during swallowing, blocking food or drink Connects to middle ear via auditory (eustachian) tube Opening tubes allows equalization of pressure on each side of tympanic membrane Contains tonsils—infection-fighting lymphatic tissue Tubal tonsils located near auditory tube opening Pharyngeal tonsil on posterior nasopharynx wall Called adenoids when enlarged

27 23.2c Pharynx Oropharynx: middle pharyngeal regionPosterior to oral cavity Extends from soft palate to hyoid bone Passageway for both food and air Lined by nonkeratinized stratified squamous epithelium Contains tonsils Palatine tonsils on the lateral walls Lingual tonsils at base of tongue

28 23.2c Pharynx Laryngopharynx: inferior, narrow region of pharynxPosterior to the larynx From level of hyoid down to esophagus Passageway for both food and air Lined by nonkeratinized stratified squamous epithelium

29 Pharynx Figure 23.5b

30 What did you learn? What are vibrissae?Between which conchae is the middle nasal meatus located? What is the difference between the lining of the oropharynx and that of the nasopharynx? In which part of the pharynx are the pharyngeal tonsils located?

31 23.3 Lower Respiratory TractDescribe the general functions and structure of the larynx. Explain how the larynx functions in sound production. Describe the structure of the trachea. Explain the structure and function of the tracheal cartilages. Describe the structural divisions of the bronchial tree. Learning Objectives:

32 23.3 Lower Respiratory Tract (continued)Explain the processes of bronchoconstriction and bronchodilation. Describe the structure and function of the components of the respiratory zone. List three types of cells found in alveoli, and describe the function of each. Explain the structure of the respiratory membrane. Learning Objectives:

33 23.3 Lower Respiratory TractIncludes conducting pathways from larynx to terminal bronchioles Includes structures involved in gas exchange: respiratory bronchioles, alveolar ducts, and alveoli

34 23.3a Larynx Larynx (voice box)Cylindrical airway between laryngopharynx and trachea Several functions Air passageway (usually open) Prevents ingested materials from entering respiratory tract Epiglottis covers superior opening during swallowing Produces sound for speech Vocal cords (ligaments) vibrate during expiration Assists in increasing pressure in the abdominal cavity Valsalva maneuver: simultaneous closure of laryngeal opening (by the epiglottis) and contraction of abdominal muscles Increased pressure facilitates urination, defecation, childbirth

35 Several functions (continued)22.3a Larynx Several functions (continued) Participates in sneeze and cough reflexes Help remove irritants from nasal cavity or lower respiratory tract Abdominal muscles contract increasing thoracic pressure Vocal cords are forcibly opened by pressure from below Explosive blast of exhaled air is a cough or sneeze

36 23.3a Larynx Larynx anatomyLaryngeal inlet (laryngeal aperture) connects pharynx and larynx Larynx formed and supported by nine pieces of cartilage Cartilages held in place by ligaments and muscles Single thyroid, cricoid, and epiglottis cartilages Paired arytenoid, corniculate, and cuneiform cartilages

37 23.3a Larynx Larynx anatomy (continued)Thyroid cartilage: large, shield-shaped Forms lateral and anterior walls of larynx Attached to lateral surface of cricoid cartilage Anterior protrusion is laryngeal prominence, or Adam’s apple Generally larger in males Enlarges during puberty; has sharper angle in males Cricoid cartilage: ring-shaped Just inferior to thyroid cartilage Epiglottis: spoon-shaped Anchored to inner aspect of thyroid cartilage Projects posterosuperiorly into the pharynx Closes over laryngeal inlet during swallowing

38 23.3a Larynx Larynx anatomy (continued)Smaller, paired cartilages located internally Arytenoid, corniculate, and cuneiform All laryngeal cartilages are made of hyaline cartilage, except the epiglottis, which is made of elastic cartilage Laryngeal ligaments are extrinsic or intrinsic Extrinsic ligaments Attach external surface of larynx to other structures (e.g., hyoid bone) Intrinsic ligaments are located within the larynx Include the vocal ligaments and the vestibular ligaments

39 Larynx Figure 23.6

40 23.3a Larynx Larynx anatomy: ligaments (continued)Vocal ligaments extend between thyroid and arytenoid cartilages Composed primarily of avascular elastic connective tissue Covered with mucosa to form the vocal folds (true vocal cords) Produce sound when air passes between them Opening between ligaments = rima glottidis Rima glottidis + vocal folds = glottis Vestibular ligaments extend from thyroid cartilage to arytenoid and corniculate cartilages (superior to vocal folds) Covered with mucosa to form the vestibular folds (false vocal cords) Play no role in sound production Protect vocal cords Opening between vestibular folds = rima vestibuli

41 Vocal Folds Figure 23.7a

42 Vocal Folds Figure 23.7b

43 23.3a Larynx Larynx anatomy (continued) Extrinsic skeletal musclesStabilize larynx and help it move during swallowing Originate on hyoid bone or sternum; insert on thyroid cartilage Intrinsic skeletal muscles Located within larynx Attach to arytenoid and corniculate cartilages Contraction results in change in dimension of rima glottidis Narrowing with adduction; widening with abduction Involved in voice production and swallowing

44 23.3a Larynx Sound production: vocal cord vibrationIntrinsic laryngeal muscles narrow opening of rima glottidis Air is forced past vocal cords during expiration Range of voice determined by length, thickness of vocal cords Males have longer and thicker folds, and so deeper voices Folds increase in length with growth, deepening range Pitch (frequency) determined by tension on vocal cords Increased tension = folds vibrate more = higher pitch Regulated by intrinsic laryngeal muscles Loudness depends on force of air passing across vocal cords More air = louder sound

45 Sound production (continued)23.3a Larynx Sound production (continued) Other structures are also necessary for speech Pharynx, nasal and oral cavities, and paranasal sinuses serve as resonating chambers Lips, teeth, and tongue help form speech sounds

46 Clinical View: LaryngitisInflammation of the larynx Symptoms of hoarse voice, sore throat, sometimes fever Caused by bacterial or viral infection, or overuse (yelling) Severe cases can extend to the epiglottis May lead to sudden airway obstruction, especially in children

47 23.3b Trachea Gross anatomy of trachea (windpipe)Flexible, slightly rigid, tubular organ Goes from larynx to main bronchi Anterior to esophagus, posterior to part of sternum About 13 cm long, 2.5 cm in diameter Tracheal cartilages support anterior and lateral walls C-shaped rings of hyaline cartilages Ensheathed in perichondrium and dense fibrous membrane Ensure trachea is always open Rings are connected to each other (above and below) by anular ligaments

48 23.3b Trachea Gross anatomy of the trachea (continued)Carina: internal ridge at inferior end of trachea (where it splits) containing many sensory receptors Initiates cough reflex when irritants are present Trachealis muscle and ligamentous membrane on trachea’s posterior surface Connects open ends of C-shaped cartilages Allow accommodation for esophagus when bulge of food passes Trachealis contracts during coughing Tracheotomy: incision in trachea to facilitate breathing Done when airway is blocked or compromised

49 Trachea Figure 23.8a-c

50 23.3b Trachea Histology of the tracheal wall Layers, inner to outerMucosa: pseudostratified ciliated columnar epithelium and lamina propria Submucosa: areolar connective tissue with blood vessels, nerves, serous and mucous glands, lymphatic tissue Tracheal cartilage Adventitia: elastic connective tissue Figure 23.8d

51 23.3c Bronchial Tree Bronchial tree: system of highly branched air passages Originates at main bronchi, branches to more narrow tubes Ends in small bronchiole passageways Gross anatomy of bronchial tree Trachea splits into right and left main bronchi (primary bronchi) at level of sternal angle Each bronchus enters a lung on its medial surface Right bronchus shorter, wider, and more vertically oriented Foreign particles more likely to lodge here

52 23.3c Bronchial Tree Gross anatomy of the bronchial tree (continued)Each main bronchus branches into lobar bronchi (secondary bronchi) Each extends into a lobe of the lung Smaller in diameter than main bronchi Further divide into segmental bronchi (tertiary bronchi) Tree continues to divide into smaller passageways Leads to tubes of <1mm, the bronchioles Leads to terminal bronchioles (last part of conducting zone) Leads to respiratory bronchioles (first part of respiratory zone)

53 Bronchial Tree Figure 23.9

54 Clinical View: BronchitisInflammation of the bronchi caused by bacterial or viral infection or inhaled irritants Acute bronchitis Occurs during or after an infection Coughing, sneezing, pain with inhalation, fever Most cases resolving in 10 to 14 days Chronic bronchitis Occurs after long-term irritant exposure Large amounts of mucus, and cough lasting >3 months Permanent changes to bronchi occur Increases likelihood of future bacterial infections

55 23.3c Bronchial Tree Histology of the bronchial treeMain bronchi are supported by incomplete rings of hyaline cartilage (keep them open) Wall support (cartilage) lessens as bronchi divide Bronchioles have no cartilage Have proportionally thicker layer of smooth muscle Muscle contraction narrows bronchiole diameter Bronchoconstriction = less air through bronchial tree (less entry of potentially harmful substances) Muscle relaxation increases bronchiole diameter Bronchodilation = more air through the bronchial tree

56 Structure of the Bronchial WallFigure 23.10

57 Clinical View: Asthma Episodes of bronchoconstriction, wheezing, coughing, shortness of breath, and excess mucus Asthmatic with sensitivity to airborne agent Localized immune reaction occurs in bronchi and bronchioles Walls of the bronchi becoming permanently thickened Primary treatments Inhaled steroids Bronchodilators

58 23.3d Respiratory Zone: Respiratory Bronchioles, Alveolar Ducts, and AlveoliRespiratory zone structures are microscopic Respiratory bronchioles subdivide to alveolar ducts Alveolar ducts lead to alveolar sacs, clusters of alveoli Alveoli = saccular outpocketings Epithelium Respiratory bronchioles lined with simple cuboidal epithelium Alveoli and alveolar ducts lined by simple squamous Thinness facilitates gas exchange

59 Bronchioles and AlveoliFigure 23.11a

60 23.3d Respiratory Zone: Respiratory Bronchioles, Alveolar Ducts, and AlveoliEach lung contains 300 to 400 million Alveolar pores: openings providing collateral ventilation Surrounded by pulmonary capillaries Divided by interalveolar septum Contain elastic fibers Figure 23.11c

61 23.3d Respiratory Zone: Respiratory Bronchioles, Alveolar Ducts, and AlveoliCell types of alveolar wall Simple squamous alveolar type I cells 95% of alveolar surface area Part of thin barrier separating air from blood Alveolar type II cells (septal cells) Secrete oily pulmonary surfactant Coats inside of alveolus and opposes collapse during expiration Alveolar macrophage (dust cells) Leukocytes that engulf microorganisms Either fixed in alveolar wall or free to migrate

62 23.3e Respiratory MembraneThe respiratory membrane Thin barrier between alveoli and pulmonary capillaries Consists of Alveolar epithelium and its basement membrane Capillary epithelium and its basement membrane Oxygen diffuses from alveolus into capillaries Erythrocytes become oxygenated Carbon dioxide diffuses from blood to alveolus Expired to external environment

63 Alveoli and Respiratory MembraneFigure 23.12

64 What did you learn? What makes one speech sound have a higher pitch than another? How does the structure of tracheal cartilages complement their function? How do bronchi and bronchioles differ? What are the differences between Type I and Type II cells in alveoli?

65 23.4 Lungs Describe the location and general structure of the lungs.Compare and contrast the right versus left lung. Distinguish between the two types of blood circulation through the lungs. Describe the innervation of lung structures by the autonomic nervous system. Learning Objectives:

66 23.4 Lungs (continued) Describe the pleural membranes and pleural cavity. Explain the function of serous fluid in the pleural cavity. Explain the anatomic properties that keep the lungs inflated. Learning Objectives:

67 23.4a Gross Anatomy of the LungLungs are in thorax on either side of mediastinum House bronchial tree and all respiratory portions of respiratory system Each lung has a conical shape Wide concave base atop diaphragm Apex (cupula) points superiorly just behind clavicle

68 23.4a Gross Anatomy of the LungLung surfaces Costal surface adjacent to ribs Mediastinal surface adjacent to mediastinum Diaphragmatic surface adjacent to diaphragm Hilum Indented region on lung’s mediastinal side Bronchi, pulmonary vessels, autonomic nerves, lymph vessels pass through here These structures collectively termed the root of the lung

69 Position of the Lungs Figure 23.13

70 23.4a Gross Anatomy of the LungRight lung is larger and wider than left lung Has three lobes divided by two fissures Horizontal fissure separates superior (upper) lobe from middle lobe Oblique fissure separates middle lobe from inferior (lower) lobe Left lung is smaller than right due to heart’s position Has two lobes divided by one fissure Oblique fissure separates superior and inferior lobes Lingula: projection from superior lobe that is homologous to right lung’s middle lobe Three surface indentations accommodate heart and aorta Cardiac impression on medial surface Cardiac notch on anterior surface Groovelike impression for aorta on medial surface

71 Lungs Figure 23.14

72 23.4a Gross Anatomy of the LungEach lung has multiple bronchopulmonary segments 10 segments in right lung; 8 to 10 in left lung Autonomous units encapsulated with connective tissues Each supplied with its own segmental bronchus Supplied with its own pulmonary artery and vein and lymph vessels Can be removed individually in cases of disease Each segment organized into lobules Each supplied by a terminal bronchiole, arteriole, venule, and lymph vessel

73 Bronchopulmonary Segments and Lobules of the LungsFigure 23.15

74 Clinical View: SmokingCauses respiratory changes with increased chance of Respiratory infections Cellular or genetic changes to the lungs Emphysema Cancer of the lungs, esophagus, stomach, and pancreas Stomach ulcers Atherosclerosis Lower birth weight babies in pregnant women Poor delivery of oxygen and nutrients to all systemic tissues Bronchitis, asthma, and ear infections from secondhand smoke

75 23.4b Circulation to and Innervation of the LungsBlood supply Two types of circulation in the lungs Pulmonary circulation Bronchial circulation Pulmonary circulation replenishes O2, eliminates CO2 Pulmonary arteries carry deoxygenated blood to pulmonary capillaries Blood is reoxygenated Blood enters pulmonary venules and veins, returns to left atrium

76 23.4b Circulation to and Innervation of the LungsBlood supply (continued) Bronchial circulation transports oxygenated blood to tissues of lungs Bronchial arteries (3 or 4) branch off descending aorta Bronchial veins collect venous blood Some drains into the pulmonary veins

77 Pulmonary Circulation of the LungsFigure 23.16

78 Clinical Views: Lung CancerHighly aggressive malignancy with early metastasis Originates in respiratory epithelium Caused by smoking in 85% of cases Symptoms of chronic cough, coughing up blood, excess pulmonary mucus, increased pulmonary infections Three basic patterns Squamous cell carcinoma Most common; arises from pseudostratified columnar epithelium; changes to stratified squamous to withstand chronic injury Adenocarcinoma Arises from mucin-producing glands Small-cell carcinoma Originates from neuroendocrine cells in the bronchi

79 23.4b Circulation to and Innervation of the LungsLymph drainage Lymph vessels and nodes located: Within lung’s connective tissue Around bronchi In pleura Important in removing excess fluid from the lungs Lymph filtered through lymph nodes Collects particles and pollutants not removed by cilia

80 23.4b Circulation to and Innervation of the LungsInnervation of the respiratory system Autonomic nervous system innervates smooth muscles and glands of respiratory structures Sympathetic input from T1–T5 generally causes bronchodilation Parasympathetic from vagus causes bronchoconstriction Sends signals to larynx from vagus nerve

81 23.4c Pleura Membranes and Pleural CavityPleura: serous membrane Outer lining of lung surfaces and adjacent thoracic wall Composed of simple squamous epithelium Visceral pleura adheres to lung surface Parietal pleura lines Internal thoracic walls Lateral surface of mediastinum Superior surface of diaphragm Each lung enclosed in a separate visceral pleural membrane Helps limit spread of infections

82 23.4c Pleura Membranes and Pleural CavityLocated between visceral and parietal serous membranes When lungs are inflated, considered a potential space Visceral and parietal layers almost touching Serous fluid produced by serous membranes Covers pleural cavity surface Lubricates, allowing pleural surfaces to slide by easily Each pleural cavity has <15 mL fluid Drained continuously by lymph

83 Clinical View: Pleurisy and Pleural EffusionPleurisy = inflammation of the pleural membranes Severe chest pain with breathing Inflamed membranes with increased friction between visceral and parietal pleura Usually only one side affected Pleural effusion = excess fluid in the pleural cavity Can cause shortness of breath and chest pain Potential causes Systemic factors: failure of the left side of the heart, pulmonary embolism, cirrhosis of the liver Lung infections or lung cancer

84 23.4d How Lungs Remain InflatedIntrapleural pressure (between membranes) is low Chest wall configured to expand outward Lungs cling to chest wall due to serous fluid’s surface tension Elastic tissue of lungs pulls inward Because intrapulmonary pressure (in alveoli) is greater than intrapulmonary pressure, lungs remain inflated

85 Pleural Membranes and Pressures Associated with LungsFigure 23.17

86 Clinical Views: Pneumothorax and AtelectasisPneumothorax = free air in the pleural cavity Air introduced externally—penetrating wound to the chest Air introduced internally—rib lacerates lung or alveolus ruptures May cause intrapleural and intrapulmonary pressures to equalize Small pneumothorax resolves spontaneously Large pneumothorax is a medical emergency Need to insert a tube into the pleural space to remove air Atelectasis = deflated lung portion Occurs if intrapleural and intrapulmonary pressures equalize Remains collapsed until air removed from pleural space .

87 What did you learn? How many lobes are there in each lung?What will happen to the diameter of bronchioles if the vagus nerve fires more action potentials? What is the pleural cavity and what is inside it?