22_Respiratory+System.pdf

Thorax & Respiratory System © K. Lisk 2024 | Division of Anatomy | University of Toronto Learning Objectives Describe the anatomy of the bony thorax Describe the functional anatomy & histology of the lower respiratory system Define & describe how the thoracic cavity changes in size & shape during br...

Thorax & Respiratory System © K. Lisk 2024 | Division of Anatomy | University of Toronto Learning Objectives Describe the anatomy of the bony thorax Describe the functional anatomy & histology of the lower respiratory system Define & describe how the thoracic cavity changes in size & shape during breathing Identify and describe the anatomy of the muscles of respiration Describe the structures involved in ventilation control 2 Bones of Thorax 12 pairs of ribs & costal cartilages 12 thoracic vertebrae & intervertebral discs Sternum Costal cartilages Manubrium Body Xiphoid process Thoracic vertebrae Intercostal space Costal margin Anterior Posterior 3 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 6.26 Ribs What type of bones are the ribs? Ribs 1-7 (true ribs): attach directly to sternum via a costal cartilage Ribs 8-12 (false ribs): attach indirectly to sternum or lack attachment Ribs 11-12 (floating): have no anterior attachment or tubercular facets Head Neck Superior view Articular facets Articulate with body of T. vertebrae Tubercle & tubercular facet Articulate with transverse process of T. vertebra Body Posterior view of a typical rib Angle Costal groove Protects blood vessels & nerves 4 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 6.26 Typical Ribs Ribs 3-9 are typical ribs Head of rib has 2 facets that articulate with 2 thoracic vertebral bodies & 1 intervertebral disc Inferior facet articulates with the superior costal facet of corresponding vertebra Superior facet articulates with the inferior costal facet of vertebra superior to it Head of rib Tubercle of rib Tubercle of rib articulates with the transverse process of the corresponding vertebra Articulations permit movements of thoracic wall Posterolateral view 5 Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 7th ed. Wolters Kluwer Fig. 4.4 Movements of Thoracic Wall Upper ribs: Elevation & depression of sternal ends of ribs Lower ribs: Elevation & depression of lateral portion of ribs Lateral view Anterior oblique view 6 Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 5th ed. Wolters Kluwer. Fig. 4.7 Jugular notch Clavicular notch Superior thoracic aperture Bordered by T1, 1st ribs, superior border of manubrium M Sternal angle B Costal notches Diaphragm attachment X T11 T12 Anterior view Xiphisternal joint Inferior thoracic aperture Bordered by T12, ribs 11 & 12, costal margins & xiphisternal joint 7 Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 7th ed. Wolters Kluwer Fig. 4.1 Movements of Thoracic Wall & Respiration Several thoracic wall muscles are involved in respiration During inhalation (inspiration) the diaphragm & external intercostals contract; increases thoracic cavity dimensions & intrathoracic volume Exhalation (expiration) is a passive process which involves the elastic recoil of lungs & relaxation of muscles I E Forced Inhalation (I) Forced Exhalation (E) 8 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.16 th Agur & Dalley. (2019). Essential Clinical Anatomy. 7 ed. Wolter Kluwer. Fig. 4.7 Diaphragm Forms floor of thoracic cavity Muscle fibers arranged radially; insert into its central tendon Blood supply: Superior & inferior phrenic vessels Innervation: Phrenic nerves (C3-C5) Central tendon Crura Attach the diaphragm to lumbar vertebrae Inferior view Martini et al. (2018). Human Anatomy. 9 9th ed. Pearson. Fig 10.12 Can you identify the structures that pass through the diaphragm? L. dome R. dome Pericardial sac Superior view 10 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 10.12 Intercostals Occupy intercostal spaces & overlap one another Fibers run in different directions; support the intercostal space External intercostals Fibers run inferiorly & anteriorly A: Elevate ribs during inhalation Innermost intercostals Internal intercostals Fibers runs inferiorly & posteriorly A: Depress ribs during forced exhalation Lateral view Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 11 7th ed. Wolter Kluwer Health. Fig. 4.10 & 4.12 Vasculature of Thoracic Wall Subclavian a. Internal thoracic v. Internal thoracic a. Drain blood anteriorly into the brachiocephalic v. & SVC Arises from subclavian a. Thoracic aorta Intercostal vv. Most drain into azygos venous system Intercostal aa. Receive blood from internal thoracic a. & thoracic aorta V A N Subcostal a. Anterior view Subcostal v. Anterior view 12 Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 7th ed. Wolters Kluwer Fig. 4.1 Venous & Lymphatic Drainage Azygos & hemiazygos vv. Drains back & thoraco-abdominal walls & viscera in these regions; collateral pathway between SVC & IVC Thoracic duct Lymphatics drain the thoracic wall into the thoracic duct 13 Moore et al. (2019). Moore’s Essential Clinical Anatomy. 7th ed. Wolters Kluwer. Fig. 4.49 Knowledge Check 1. Identify muscle A. 2. True or False. In addition to the intercostals, there are other muscles that attach to the thoracic wall which can be involved in respiration. A 14 Respiratory System Divided structurally into upper & lower respiratory tracts Nasal cavity Functionally divided into conducting & respiratory parts Pharynx Upper respiratory tract Lower respiratory tract Nose Larynx Trachea Bronchi Bronchioles 15 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.1 Thoracic Cavity Divided into 3 compartments Mediastinum Serous membranes line each cavity Media = middle, stinum = partition Between pleural spaces Pericardial cavity Contains heart Right pleural cavity Contains R. lung Left pleural cavity Contains L. lung Anterior view 16 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 1.17 Mediastinum Cavity extends between sternum anteriorly & thoracic vertebrae posteriorly Bordered laterally by lungs Superior mediastinum Aortic arch, tracheal bifurcation & SVC Inferior mediastinum Middle mediastinum Vagus n. pericardial sac & contents Posterior mediastinum Transverse section, superior view Trachea & primary bronchi, esophagus, great vessels, loose areolar CT Anterior mediastinum Thymus, loose CT, BVs, nerves Lateral view 17Pearson. Fig 21.4 Martini et al. (2018). Human Anatomy. 9th ed. th Moore et al. (2014). Moore’s Essential Clinical Anatomy. 5 ed. Wolters Kluwer Fig. 1.23 Serous Membranes Line walls of body cavities & their contents; do not open to exterior Parietal & visceral layers are continuous Consist of a mesothelium; simple squamous epithelium attached to loose areolar CT Serous cavity contains transudate which provides lubrication & creates tension between the membranes Parietal pleura Visceral pleura Pleural cavity contains pleural fluid 18 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 1.17 Pleural Recesses Empty lungs do not completely fill the pleural cavities; leaves spaces that accommodate the expansion of the lungs with inhalation 1. Costodiaphragmatic recess Gutter around the costal edge of the base of the lung 2. Costomediastinal recess Extension of the pleural cavity between the sternum & the mediastinum (not shown) 19 CC0; Mikael Haggstrom Pleural Effusion Excess fluid in pleural space Transudative pleural effusion: caused by changes in hydrostatic pressure (e.g., BP or low protein count) Excess fluid in pleural space Exudative pleural effusion: caused by inflammatory conditions, infection, lung injury &/or tumor Excess fluid + protein + immune cells in pleural space Case courtesy of Abdelkader Mallouk, Radiopaedia.org, rID: 71570 20 Lungs Apex Cone shaped Lobes are separated by deep fissures Each lobe has 3 surfaces: Base M 1. Costal (C) 2. Mediastinal (M) C 3. Diaphragmatic (D) Superior lobe Horizontal fissure Superior lobe C C Oblique fissure M Middle lobe Inferior lobe C Oblique fissure Inferior lobe Anterior view D 21 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 23.6 & 23.8 S: superior lobe M: middle lobe I: inferior lobe S Hilus Contains root of lung S Groove for aorta M I Right, mediastinal view Esophageal impression Cardiac impression Cardiac notch I Left mediastinal view The root of the lung consists of the 1° bronchi, pulmonary arteries (blue), veins (red), nerves & lymphatics enclosed in CT 22 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 23.8 Knowledge Check 1. Identify 1. 2. The number 3 represents the groove for which structure? 3. Identify 6. 23 Hyoid Larynx (1°) Annular ligaments (2°) Join tracheal rings Trachea (3°) Tracheal rings 15-20, C-shaped Carina of trachea Right 1° bronchus Wider, shorter, vertical compared to left Bifurcation of trachea Left 1° bronchus 2° bronchi 1 per lung lobe 3° bronchi 1° bronchi enter the hilus of each lung 24 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.9 Trachea Connects larynx to primary bronchi & is lined with respiratory mucosa Consists of 15-20 C-shaped hyaline cartilage rings separated by elastic annular ligaments Trachealis muscle located posteriorly; relaxes with sympathetic stimulation → bronchodilation RE: Respiratory epithelium LP: Lamina propria G: Seromucous glands in submucosa P: Perichondrium C: Hyaline cartilage Mescher. (2018). Junqueira’s Basic Histology. 15th ed. Mc Graw Hill. Fig 17.5 Cui et al. (2011). Atlas of Histology with Functional and Clinical Correlations. 1st ed. Wolters Kluwer. Fig. 11.6a X50; H&E 25 1° bronchus 3° bronchi 1 per lung lung (1°) 1 per bronchopulmonary segment (2°) (3°) S 2° bronchi S 1 per lung lobe M I I S: superior lobe M: middle lobe I: inferior lobe Each lung has 9-10 bronchopulmonary segments; lung tissue supplied by a given 3° bronchus Each 3° bronchus branches several times forming bronchioles 26 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 23.9 Histology of Bronchi 1° bronchus Respiratory mucosa, fewer goblet cells 3° bronchi Amount of cartilage decreases through the 1°, 2°, 3° bronchi 3° bronchi branch repeatedly forming terminal bronchioles Circular layer of smooth muscle appears in bronchi & is prominent in bronchioles 2° bronchi C E L Lumen of 1° bronchus SM 8.7x MH 139. © 2005-2024. T. Clark Brelje & Robert Sorenson. Histology Guide. RE: Respiratory epithelium LP: Lamina propria SM: Smooth muscle C: Hyaline cartilage 27 Histology of Bronchioles Epithelium changes to simple ciliated columnar/cuboidal to simple cuboidal/low columnar which are bronchiolar exocrine (Club) cells Lack mucosal glands & cartilage; prominent smooth muscle bundles (SM) Found adjacent to blood vessels & are surrounded by alveoli (A) A Branching of bronchioles ends as respiratory bronchioles SM 8.8x MH 139. © 2005-2024. T. Clark Brelje & Robert Sorenson. Histology Guide. 28 Bronchiole Lumen of terminal bronchiole LE X300; PT Mescher. (2018). Junqueira’s Basic Histology. X500; PT 15th ed. Mc Graw Hill. Fig 17.10 Respiratory bronchioles Terminal bronchioles 29 Respiratory Portion of Resp. System Site of gas exchange which occurs across respiratory membrane Terminal bronchiole Respiratory bronchiole Alveolar ducts Visceral pleura Alveolar sac Alveoli 30 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 23.10 Primary Lobule Each terminal bronchiole delivers air to a single pulmonary lobule Terminal bronchiole Terminal bronchiole branch into respiratory bronchioles Respiratory bronchioles branch into alveolar ducts which branch into alveolar sacs & individual alveoli Smooth muscle & elastic fibers Respiratory bronchioles Alveolar duct Alveolar sac Clusters of alveoli ura e l p l era cavity c s i V ural a e ur Ple l p l ieta r a P Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.13 Primary Lobule Bronchial vessels & nerves supply lung tissue itself Capillary beds Art eri ole Branches of pulmonary arteries form capillary beds around alveoli for gas exchange; coalesce as pulmonary venules à veins Branch of pulmonary artery Bronchial V. A. N Where is this blood going? Lymphatic vessel Branch of pulmonary vein Pulmonary venule Vis ura e l p l cera vity ca ral u ura e Pl pl e l ieta r a P Respiratory bronchioles (RB) lined with bronchiolar exocrine (Club) cells & are surrounded by alveoli; subdivide into alveolar ducts (AD) which consist of simple squamous epithelium X14; H&E PA: branch of pulmonary artery V: branch of pulmonary vein X140; H&E AS: alveolar sacs A: alveoli 33 Mescher. (2018). Junqueira’s Basic Histology. 15th ed. Mc Graw Hill. Fig 17.12 Alveoli Responsible for spongy structure of lungs & site of gas exchange Resembles a pouch; open on 1 side to alveolar duct or sac Between alveoli lie interalveolar septa; fibroblasts, elastic & reticular fibers Elastic & reticular fibers Pulmonary capillaries Type II alveolar cells (pneumocyte) Rounded cells with vacuolated cytoplasm Secrete surface-active agent; ↓ surface tension, maintains alveolar patency Type I alveolar cell (pneumocyte) Alveolar macrophage Phagocytose particulate matter Form simple squamous epithelium 34 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.14 X450; H&E A: alveoli C: capillary II: type II alveolar cells I: type I alveolar cells M: macrophage 35 Mescher. (2018). Junqueira’s Basic Histology. 15th ed. Mc Graw Hill. Fig 17.14 Blood Air Barrier Respiratory membrane consist of 3 structures (1, 2, 3) Gas exchange is rapid due to thinness (~0.5μm) of membrane & small, lipid-solubility of gases O2 RBC Capillary lumen Basement membrane (2) Endothelium (1) um(3) li e h it p e r la o Alve Surfactant Nucleus of endothelial cell CO2 Alveolar air space 36 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.14 Emphysema Damaged & permanently enlarged alveoli, causing breathlessness Destruction of elastic fibers in lungs & air becomes trapped in lungs at end of exhalation H&E X27 CC BY-SA 2.0; Yale Rosen 37 Cui et al. (2011). Atlas of Histology with Functional and Clinical Correlations. 1st ed. Wolters Kluwer. Fig. 11.16b Trachea Bronchi Bronchioles Alveoli Epithelium Lamina Propria Secretory Cells Cartilage Rings Smooth Muscle Adventitia Word version posted on Quercus Answers posted in ANA300Y Workshop 11 38 Breathing During inhalation thoracic cavity dimensions & intrathoracic volume increase à air is drawn into the lungs Pleura cavity Potential space containing pleural fluid; important role in respiration Structure of pleura & lungs enable this to occur Pleural fluid creates tension between pleura membranes Inherent elasticity of the lungs permit them to expand & therefore remain in contact with thoracic wall Parietal pleura Covers diaphragmatic, mediastinal & costal surfaces of pleura cavity Visceral pleura Attaches directly to lung Exhalation is typically a passive process; recoil of lungs & relaxation of muscles 39 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 1.17 Inhalation Exhalation 40 Martini et al. (2018). Human Anatomy. 9th ed. Pearson. Fig 24.16 Neural Control of Respiration Higher Centers Rate & depth of breathing matched with tissue demands for O2 delivery & CO2 removal Cerebral cortex Limbic system Hypothalamus Pontine & medullary respiratory rhythmicity nuclei control the basic rate & depth of breathing CSF Chemoreceptors P Efferent fibers of the posterior respiratory group (PR) control activity of muscles of inspiration Pons P PR Medulla AR CN IX & X Efferent fibers of the anterior respiratory group (AR) coordinate innervation of both inspiratory & expiratory muscles Respiratory Rhythmicity Centers CN X Pontine respiratory group (P) adjusts respiratory pace in response to higher level input from CNS Motor neurons controlling diaphragm Motor neurons controlling other respiratory muscles Phrenic nerve 41Stimulation Inhibition Regulation of Respiratory Centers Cerebral cortex & hypothalamus has connections with respiratory centers Reflexes involved in regulating respiration: Mechanoreceptors stimulated by changes in volume or BP Chemoreceptors respond to changes in [CO2], [H+], & [O2] of blood & CSF Glossopharyngeal n. CN IX Carotid body Vagus n. CN X Aortic bodies 42 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Fig 23.15 Knowledge Check Which of the following statements is correct? A. Neurons that arise in the pontine respiratory group directly innervate the diaphragm B. Changes in blood pressure is relayed to pontine respiratory nuclei via CNs IX & XII C. The basic breathing rate is set by autonomic nuclei located in the pons & medulla D. Chemoreceptors within the carotid bodies are stimulated by a decrease in oxygen concentration Identify the feature. 43 References Agur & Dalley. (2019). Moore’s Essential Clinical Anatomy. 7th ed. Wolters Kluwer. Ch 4 Cui et al. (2011). Atlas of Histology with Functional and Clinical Correlations. 1st ed: Ch 11 Martini et al. (2018). Human Anatomy. 9th ed. Person Education. Ch 6, 10, 24 Mescher. (2018). Junqueira’s Basic Histology. 15th ed: Ch 17 Tortora & Nielsen. (2017). Principles of Human Anatomy. 14th ed. Wiley. Ch 7, 11, 23 44