Anatomy Of The Respiratory System HSC1007 PDF

ANATOMY OF THE RESPIRATORY SYSTEM HSC1007 Anatomy and Physiology 1 Dr Karthik S. Harve Associate Professor and Specialty Lead for Anatomy Health and Social Sciences Cluster Singapore Institute of Technology, SG 138683 [email protected] ...

ANATOMY OF THE RESPIRATORY SYSTEM HSC1007 Anatomy and Physiology 1 Dr Karthik S. Harve Associate Professor and Specialty Lead for Anatomy Health and Social Sciences Cluster Singapore Institute of Technology, SG 138683 [email protected]  SIT Internal LEARNING OUTCOMES FROM TODAY’S LECTURE Structures forming the respiratory system Primary functions of the respiratory system Division of the respiratory system based on structure and function How does the structure of the respiratory system facilitate its function? Mechanics and mechanism of the function of respiration  SIT Internal A COMMON SCENARIO A NOT SO COMMON SCENARIO A SIMPLE URTI (UPPER RESPIRATORY TRACT INFECTION) A SERIOUS LRTI (LOWER RESPIRATORY TRACT INFECTION) Picture source: Wikimedia Commons Picture source: Wikimedia Commons  SIT Internal WHAT STRUCTURES FORM THE RESPIRATORY SYSTEM? Upper Respiratory Tract: - Nasal passages - Pharynx - Larynx (level of glottis) Lower Respiratory Tract: - Sub-glottis & Trachea - Bronchi - Bronchiole - Alveolus https://upload.wikimedia.org/wikipedia/commons/a/a4/Upper_respiratory_tract.jpg  SIT Internal UPPER RESPIRATORY TRACT Nasal Passages: - Nasal Vestibule - Nasal Cavities Pharynx: - Nasopharynx - Oropharynx - Laryngopharynx Larynx: - Laryngeal inlet - Cavity of larynx - Glottis Modified from: Textbook of Histology and Practical Guide by J P Gunasegaran licensed under creative common  2 Turbinates → slow down air flow to enable air conditioning & filtering 3 turbinates Goblet cell 1 Picture modified from Netter’s Atlas of Human Anatomy, Elsevier Ltd Wine Nasal Mucosa: Respiratory Epithelium: Pseudostratified Ciliated Columnar with Goblet Goblet cells Nasal Vestibule: skin & hair (vibrissae) Roof: Olfactory epithelium ❑ Lining respiratory epithelium Pictures sourced from: - ciliated columnar cells (move mucus) OpenStax, Anatomy & Physiology. Lateral walls: Respiratory epithelium OpenStax CNX. Feb 26, 2016 http://cnx.org/contents/14fb4ad7- - goblet cells (secrete mucus) [email protected]. - sensory cells (sneeze, cough) Histology Picture courtesy: Department of Anatomy, Yong Loo Lin School of ❑ Seromucous glands in lamina propria (beneath epithelium) Medicine, National University of Singapore 117594 ❑ Blood vessels in lamina propria: warm the air  SIT Internal PHARYNX Nasal septum Nasopharynx Oropharynx Laryngopharynx * Vocal cords (Glottis) * → Sub-glottis Pictures sourced from: OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, Picture modified 2016 http://cnx.org/contents/[email protected]. from Netter’s Atlas of Human Functional significance: Separation of food and air pathways Anatomy, Elsevier Ltd  SIT Internal Larynx ❑ A cartilaginous assembly connected by ligaments & membranes ❑ Epiglottis forms the inlet ❑ Thyroid & Cricoid cartilages bound the cavity ❑ Main function: prevent asphyxiation (choking) ❑ Voice production(phonation) → vocal cords (folds) ❑ Muscles move the vocal folds Vocal folds pulled away Vocal folds close together ‘Abduction’ ‘Adduction’ Pictures sourced from: OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, 2016 (‘Abduction’) (‘Adduction’) http://cnx.org/contents/[email protected].  SIT Internal TRACHEA IN NECK & MEDIASTINUM C6 (cricoid cartilage) T4 (sternal angle) Carina(tracheal bifurcation) Picture source: Wikimedia Commons Picture modified from Netter’s Atlas of Human Anatomy, Elsevier Ltd Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. TRACHEAL CROSS SECTION AND HISTOLOGY Pictures sourced from: OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, 2016 ciliated http://cnx.org/contents/14fb4ad7-39a1-4eee- [email protected]. Respiratory Epithelium (1) Lamina propria (2) Seromucous glands (3) Hyaline cartilage (4) Trachealis (smooth muscle) (6) 1 2 Picture courtesy: Wheater’s Functional Histology, 6th Edition, Elsevier Ltd  SIT Internal THE PRIMARY BRONCHI AND THEIR DIFFERENCES Compared to the left, the right main bronchus is: More vertical Wider in diameter Shorter in length R L Clinical Implication Picture modified from Netter’s Atlas of Human Anatomy, Elsevier Ltd Foreign bodies more likely to be aspirated into the right side R L A bronchoscopic view of the tracheal bifurcation Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal Case scenario: Previously healthy child presented with cough after aspiration of a metal screw Choking, coughing, neck pain, or struggling to breathe are common presentations of an aspirated foreign body. The right main bronchus is the most common site of obstruction due to its larger lumen and more vertical orientation. Hamidi H, Screw in bronchus. Case study, Radiopaedia.org; https://doi.org/10.53347/rID-52530 Functional Division of the Respiratory Tract Conducting zone: Nose to terminal bronchiole Bronchus: No gas exchange → anatomical ‘dead’ space (~ 150 ml) - Respiratory epithelial lining - Smooth muscle beneath the epithelium Nasal passages to terminal bronchiole - Broken cartilage in walls - Seromucous glands Primary source of airway resistance (bronchi) Airway resistance increases in Asthma Bronchiole: - Lumen diameter 15ml Diaphragm Chest wall +ve intrapleural pressure contracts expands At rest reduced lung expansion -ve Intrapleural pressure decreases further → -ve Intra-alveolar pressure → Inspiration Pictures sourced from: OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, 2016 http://cnx.org/contents/[email protected].  SIT Internal CHEST X-RAY: FLUID ACCUMULATION IN PLEURAL CAVITY (EFFUSION) Picture source: Wikimedia Commons CXR shows normal costophrenic angle Pleural effusion: blunted right costophrenic angle (Samui K et al. 2017) PNEUMOTHORAX AND CHEST WALL INJURY Presence of air in pleural cavity May result from rib fractures/stab wounds to the chest Positive intrapleural pressure Shift of trachea and mediastinal structures to opposite side There may be collapse of lung on the affected side Consequence → Reduced Alveolar Ventilation Picture courtesy: Karthik Easvur / CC-BY-SA-3.0  SIT Internal THE LUNGS: SURFACES, BORDERS AND MAIN PARTS Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal KEY RELATIONS OF THE LUNGS Right Lung Left Lung Cross-section of thoracic cavity viewed from below Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal LUNGS: LOBES AND FISSURES Cardiac notch Right Lung Left Lung Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal BRONCHOPULMONARY SEGMENTS OF THE LUNGS Lobes → bronchopulmonary (BP) segments 10 BP segments in each lung Each Bronchopulmonary segment has its own Bronchus (air-supply) Artery (blood supply) So it is an independent structural and functional unit of the lung Picture modified from Netter’s Atlas of Human Anatomy, Elsevier  SIT Internal FURTHER DIVISIONS OF THE AIRWAYS Size Within the Lung Conducting Zone bronchi bronchioles terminal bronchiole Respiratory Zone respiratory bronchiole Alveolar ducts Alveolar sacs and alveoli Creative Commons Attribution 4.0 International Surface area  SIT Internal CHANGES ALONG THE WALL OF THE TRACHEOBRONCHIAL TREE Secreting cell Cartilage in the Smooth muscle in the Glands in the connective Structure Lining Epithelium in Epithelium wall wall tissue of the wall Loss of Pseudostratification Decrease in height of cells Disappearance of goblet cells Trachea Pictures modified from: OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, 2016 Alveolus http://cnx.org/contents/[email protected].  SIT Internal The Alveolus: structure and cells 5 main cell types present : Type 1 pneumocyte → Simple squamous epithelium → 1. Capillary gas exchange endothelial cells Type 2 pneumocyte → surfactant (a phospholipid) 2. Type 1 pneumocytes synthesis 3. Type II pneumocytes 4. Interstitial cells: Alveoli vary in size from small alveoli to large alveoli include fibroblasts Interalveolar connections via pores (of Kohn) and mast cells Surfactant lowers surface tension in alveoli to prevent 5. Alveolar their collapse macrophages - digest the debris Lack of surfactant in premature babies → Respiratory distress syndrome Picture modified from Wikimedia Commons  SIT Internal THE THORACIC WALL Skeletal components - Ribs - Vertebrae - Sternum - Costal cartilages - Associated ligaments Musculoaponeurotic components - Diaphragm - Intercostal muscles - Suprapleural membrane - Fasciae Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. THE THORACIC WALL: KEY LANDMARKS Posterior axillary line Anterior axillary line Midclavicular line Scapular line Mid-axillary line Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  The Typical Rib The Sternum and costal cartilages Picture courtesy: Gray’s Anatomy for students, 3rd Note: Both sternum and ribs contain red bone marrow Edition, Elsevier Ltd. Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. Question→ Can you find out what is an ATYPICAL rib ?  SIT Internal JOINTS OF THE RIB CAGE Joints between ribs and vertebrae Picture courtesy: McMinn’s Clinical Atlas of Human Anatomy, 7th Edition, Elsevier Ltd 4 Articular facet of transverse process 5 Articular part of tubercle 17 Neck of rib 18 Non-articular part of tubercle Picture courtesy: Gray’s Anatomy for 23 Upper costal facet of head of rib students, 3rd Edition, Elsevier Ltd. 24 Upper costal facet of vertebral body  SIT Internal CHEST WALL MOVEMENTS FOR RESPIRATION Pump Handle Motion Bucket Handle Motion Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. Forward movement of sternal body at manubriosternal joint Increases the anteroposterior diameter of thoracic cavity Elevation of 6-10 ribs at the costovertebral Involves 2nd to 5th ribs mainly and sternocostal joints First rib fixed (no movement) Increases transverse diameter of the cavity  SIT Internal PRINCIPAL MOVEMENTS FOR RESPIRATION IN ALL 3 DIMENSIONS Increased A-P diameter Increased transverse diameter Increased vertical diameter Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. DIAPHRAGM: ATTACHMENTS AND INNERVATION Phrenic nerves Origin: Cervical spinal segments C3,4,5 Picture modified from Netter’s Atlas of Human Anatomy, Elsevier  DIAPHRAGM: OPENINGS SIT Internal Caval opening Aortic Esophageal hiatus opening Picture courtesy: Aorta Viewed from below Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. Picture modified from Netter’s Atlas of Human Anatomy, Elsevier  SIT Internal INTERCOSTAL MUSCLES External Intercostal Internal Intercostal - Adjacent borders of upper and lower ribs - Adjacent borders of upper and lower ribs - Run downwards & forwards - Run downwards & backwards Internal Intercostal functions External intercostal functions - Depress ribs in forced - Elevate ribs in inspiration expiration - Stiffen chest wall - Stiffen chest wall Picture modified from Netter’s Atlas of Human Anatomy, Elsevier INNERMOST LAYER OF INTERCOSTAL MUSCLES: 3 PARTS 1. Transversus thoracis back of sternum to costal cartilages 2. Innermost intercostal side of upper to lower ribs (shafts) on their inner surfaces 3. Subcostalis posterior part of ribs on their inner surfaces Function: Most active in Forced expiration Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal THE INTERCOSTAL SPACE Picture courtesy: McMinn’s Clinical Atlas of Human Anatomy, 7th Edition, Elsevier Ltd Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd. Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal ACCESSORY MUSCLES FOR BREATHING Sternocleidomastoid Expiratory muscles Pectoralis Serratus major anterior Inspiratory muscles Pictures modified from Netter’s Atlas of Human Anatomy, Elsevier Picture courtesy: Gray’s Anatomy for students, 3rd Edition, Elsevier Ltd.  SIT Internal MUSCLES OF RESPIRATION Muscles of Inspiration Accessory Inspiratory Muscles * Muscles of Forced Expiration Diaphragm Scalene muscles Internal Intercostal External Intercostal Sternocleidomastoid Innermost Intercostal Pectoralis Major External Oblique Serratus Anterior Internal Oblique Levator Costarum Transversus Abdominis Erector Spinae Rectus Abdominis These are 6 examples of accessory muscles involved in respiration * Not active during quiet inspiration End of Lecture