HUBS192 Lecture 16, 2024 Respiratory System Anatomy PDF

HUBS192 Lecture Material This pre-lecture material is to help you prepare for the lecture and to assist your note-taking within the lecture, it is NOT a substitute for the lecture ! Please note that although every effort is made to ensure this pre-lecture material...

HUBS192 Lecture Material This pre-lecture material is to help you prepare for the lecture and to assist your note-taking within the lecture, it is NOT a substitute for the lecture ! Please note that although every effort is made to ensure this pre-lecture material corresponds to the live-lecture there may be differences / additions.  HUBS192 Lecture 16 Anatomy of the Respiratory System – III romahā mātai tinana - III Anatomy of the Thorax & Breathing (Ventilation) Dr. Niranjan Ramesh Department of Anatomy © The content and delivery of all resources in this course are copyrighted. This includes video and audio recordings, PowerPoints, lecture notes and handouts. You may access the materials provided for your private study or research but may not further distribute the materials for any purpose, or in any other form, whether with or 19th August 2024 without charge.  Lecture Objectives (Lecture 16) Describe the key anatomical features of the thoracic cavity, including the joints, muscles, and pleural membranes. Explain the relationship between pressure and volume for gas and how this relates to breathing. Describe how the anatomical features facilitate changes of the volume of the thorax. Describe the anatomical mechanism of breathing. Pre-reading from Martini et al., Visual Anatomy and Physiology (3rd ed): Body cavities: Module 1.22 Thoracic cavity (page 85) The thoracic cage: Module 7.14 (pages 306-7) Thoracic cavity and its volume: Module 18.2 (pages 702-3 figures 1 & 4) Pulmonary ventilation: Module 21.9 (pages 854-855) Respiratory muscles: Module 21.10 (page 856) 2 Word Cloud for Recall (Lecture 16) 3  Homework Answers L15 1. Which of these is NOT associated with the respiratory membrane? A. Capillary endothelium B. Simple squamous epithelium C. Type 2 pneumocytes D. Fused basement membrane 2. Which cells remove debris from the alveoli? A. Pseudostratified ciliated columnar epithelium B. Goblet cells C. Type 2 pneumocytes D. Macrophages 4  Lectures 14 & 15 – A Recap ❖ URT & LRT bring air in optimum condition to the respiratory membrane. ❖ Larynx prevents entry of food to LRT and contains the vocal cords. ❖ The bronchial tree carries air to alveoli, with changes to the epithelium, smooth muscle and cartilage reflecting function. ❖ Gas exchange occurs at the respiratory membrane in the alveoli. Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.1, p.839 5  Body Cavities Our body cavities are lined with serous membranes Double layer of secretory tissue with fluid between layers Visceral layer on the organ Parietal layer on body wall Thoracic cavity Pericardium Pleura x 2 Abdominopelvic cavity Peritoneum 6  The Thoracic Cavity Contains Boundaries of the Thoracic Cavity Mediastinum SUPERIOR (Root of neck) Heart, vessels, pericardium Pleural cavities Lungs ANTERIOR POSTERIOR (Vertebrae) Boundaries (Sternum) Anterior: Sternum LATERAL LATERAL Posterior: Thoracic (Ribs/Intercostal muscles) (Ribs/Intercostal muscles) vertebrae Lateral: Ribs INFERIOR Superior: base of neck (Diaphragm - muscular) Inferior: diaphragm 7 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 7.14, p.306  The Thoracic Cavity 1st rib Mediastinum - heart, vessels, pericardium Pleural cavities – lungs are separate so if one stops functioning, you have another Diaphragm Pleural cavity Hilum of lung - where Parietal pleura 1˚ bronchus, vessels Visceral pleura enter 8 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module, 18.2, p703  Ventilation is driven by pressure changes in thoracic cavity Pressure is inversely proportional to volume So, if we change the Inspiration: volume increases volume of the thorax, we change the pressure Expiration: volume decreases 9 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.9, p 855  Boyle’s Law P = 1/V Pressure inversely proportional to volume Pressure measured by collisions: smaller space = more collisions = increased pressure bigger space = less collisions = decreased pressure Air will move to lower pressure space 10 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.9, p.854  Boyle’s Law To breathe, we need to establish a pressure gradient to make air move Between breaths- pressure inside cavity = pressure Inspiration – volume increases outside. No gradient Pout > Pinside - air flows in Increase volume (therefore decrease pressure) – air flows in Decrease volume (therefore increase pressure) - air flows out How do we change the volume of the thorax? Expiration – volume decreases Pout < Pinside - air flows out 11  Thoracic Joints: Anterior Sternum to Ribs via costal cartilage (hyaline) - Synovial joints - Cartilaginous joints Sternocostal - Synovial - Except 1st = cartilaginous Costochondral - cartilaginous Interchondral - synovial 12 Drake et al, Gray’s Anatomy for Students, 2nd Edn., 2010  Thoracic Joints: Posterior Costotransverse between rib and transverse process of vertebrae Drake et al, Gray’s Anatomy for Students, 2nd Edn., 2010 Costovertebral between rib and body of Articulation between vertebrae thoracic vertebrae and ribs Synovial joints Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 7.14, p.307 Joints allow movement to occur, but we need muscles to create the movement 13  How long can you hold your breath? Average person can hold their breath 30-90 seconds Diving reflex – Triggered by cooling and wetting face and nose – Sends more oxygen to heart and brain = increases time holding breath – Babies have an innate diving reflex up to ~ 6 months Current world record: 24 minutes 37 seconds – Budimir Šobat from Croatia in 2021 Inhaled pure oxygen beforehand – Longest unassisted: 11 mins 34 seconds 14  Practice Questions 1. Which of the thoracic joints are NOT synovial joints? 2. What is the name of the law that describes the relationship between pressure and volume of a gas? 15  Muscles of Respiration Respiratory muscles move the rib cage to allow us to breathe Intercostals Primary muscles of respiration Diaphragm Intercostals Accessory muscles Active only when needed Diaphragm 16 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.10, p.856  The Diaphragm Sternum Sheet of skeletal muscle Separates thorax from the Inferior vena cava Esophagus abdomen Dome-shaped when relaxed Flattens when contracted Contraction expands the thoracic cavity, and compresses abdominopelvic cavity 12th rib Aorta Inferior view of diaphragm 17 Relaxed Contracted Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 10.10, p.411  Intercostal Muscles Attach diagonally between neighbouring ribs External intercostals Lift ribcage and expand cavity Inspiration- quiet and forced Internal intercostals Depress ribcage and decrease cavity Expiration- forced only 18 Drake et al, Gray’s Anatomy for Students, 2nd Edn., 2010  Accessory Muscles Several muscles that attach to the thoracic cage You do not need to know the individual names of these! You definitely need to know their collective functions: Some accessory muscles increase cavity volume for forced inspiration Other accessory muscles decrease cavity volume for forced expiration 19 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.10, p.856 Muscles of Respiration: Inspiration During normal ‘quiet’ inspiration Diaphragm contracts = flattens External intercostals contract = lifts ribs During active ‘forced’ inspiration As above, plus accessory muscles contract to further expand thoracic cavity 20 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.10, p.856 Muscles of Respiration: Expiration During normal ‘quiet’ expiration Passive process Diaphragm relaxes = dome shaped External intercostals relax = ribs no longer lifted During active ‘forced’ expiration As above plus: Internal intercostals contract = depress ribs Accessory muscles contract to further decrease cavity volume 21 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.10, p.856  How do the lungs expand as the cavity does? Lung tissue is elastic and always trying to recoil The pleura make the lungs ‘stick’ to the thoracic wall Lungs expand during inspiration Lungs contract during expiration 22 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.9, p.855  Thoracic Movement: Pleura Pleural cavity diaphragm Visceral pleura on lungs Parietal pleura on thoracic wall Pleural fluid in between – Slippery surface for frictionless movement against other structures – Fluid bond causes lungs to ‘stick’ to thoracic wall Therefore, thoracic wall movement results in lung movement – Increase volume of thorax increase volume of lung decrease pressure in lung air flows in 23 Martini et al, Visual Anatomy & Physiology, 3rd Edn, Module 21.9, p.854  Pneumothorax Air collects in pleural space The collapse of part or the entire lung Physical trauma or as spontaneous response to lung disease 24  Practice Question It’s your birthday! Describe what muscles will be contracting to allow you to blow out the candles on your cake. 25  Summary What are the key anatomical features of the thoracic cavity? What is the relationship between pressure and volume? How do the anatomical features change thoracic volume? How does our anatomy facilitate breathing? 26  How does it all fit together? Bonus Features Conducting Passages Olfaction keep airway patent Specialised epithelia cartilage Sound production ensure air optimal condition Vocal folds warm, clean and moist Sinuses as resonating respiratory epithelium chambers EFFECTIVE GAS EXCHANGE Gas exchange barrier/ Movement of air in and out of respiratory membrane lungs Air and blood in close Structures of thoracic cavity proximity Joints Type 1 pneumocytes form the Muscles alveolar wall Change in volume = change in Fused basement membrane pressure Capillary wall (endothelium) Draw air in or out  HUBS192 Copyright Warning Notice This coursepack may be used only for the University’s educational purposes. It includes extracts of copyright works copied under copyright licences. You may not copy or distribute any part of this coursepack to any other person. Where this coursepack is provided to you in electronic format you may only print from it for your own use. You may not make a further copy for any other purpose. Failure to comply with the terms of this warning may expose you to legal action for copyright infringement and/or disciplinary action by the University