Respiratory System - Conducting - 2023 PDF

Assoc.Prof. Özlem Tuğçe Çilingir-Kaya Histology & Embryology Department Marmara University School of Medicine  The lungs and a sequence of airways lead to the external environment  Main function;  Providing oxygen (O2) to and  Eliminating carbon dioxide (CO2) from the cells of the bod...

Assoc.Prof. Özlem Tuğçe Çilingir-Kaya Histology & Embryology Department Marmara University School of Medicine  The lungs and a sequence of airways lead to the external environment  Main function;  Providing oxygen (O2) to and  Eliminating carbon dioxide (CO2) from the cells of the body.  It is subdivided into two major components: 1.The conducting portion; situated both outside and within the lungs, conveys air from the external milieu to the lungs. 2.The respiratory portion; located strictly within the lungs, functions in the actual exchange of oxygen for carbon dioxide (external respiration).  Conveys air to and from the respiratory portion of the respiratory system  Composed of 1. Nasal cavities & associated sinuses 2. Mouth 3. Nasopharynx & pharynx 4. Larynx 5. Trachea 6. Bronchi and bronchioles  Functions: 1. Filter, 2. Moisten, and warm the inspired air before it is 3. Transported to the respiratory portion of the lungs.  NCs and the paranasal sinuses provide an extensive area for warming and moistening air and filtering dust particles. 1. Vestibule = Anterior Aspect of the Nasal Cavity  The first ~1.5 cm of the conductive portion following the nostrils  Keratinised stratified squamous epithelium  Short, stiff hairs that prevent larger dust particles from entering the nasal cavity  Sebaceous glands which one of below is right about nasl cavity all tha nasal caity is lined by respiratory epoithelium. 2. Respiratory region = Posterior Aspect of the Nasal Cavity  Mucus producing goblet cells  The nasal cavity is lined by pseudostratified ciliated columnar epithelium = Respiratory Epithelium  Except for the vestibule and the olfactory region 3. Olfactory Region of the Nasal Cavity  Comprises the olfactory ep. and the underlying l.propria that houses Bowman’s glands and a rich vascular plexus  Tissues on the superior concha and the nasal septum form the olf. region  The surface of the lateral parts of the nasal cavity is thrown into folds by bony projections called conchae.  Increase the surface area of the nasal cavity  Create turbulence in the stream of passing air,  warming, cooling, and filtration 1. Olfactory cells (receptors)  Bipolar neurons which cell was a neuron ?  Have central bulge, containing nucleus  Dendritic process extends to the surface, its tip is expanded into olfactory vesicle.  Cilia have 9+2 arrangement but they do not move  They lack dynein arms. 2. Sustentacular cells (supporting)  The nuclei closest to the lumen  Moderate amount of rER and numerous mitochondria  Small accumulation of yellow-brown pigment and numerous microvilli on the luminal surface 3. Basal cells which one the fallowing is right  The nuclei closest to the basement membrane olfactory are they are non motile  Are not in contact with the lumen sustentucular cells are clossest to lumen  Are not form the stem cell from which new having enormous amoun t of mit olfactory cells can develop basal cells are not devloped from the stem cells which develop olfactery cell all  Cavernous spaces in the; 1. Maxillary 2. Ethmoid 3. Sphenoid 4. Frontal bones of the face  Large, mucoperiosteum-lined spaces, communicate with the main nasal cavity.  The mucosa comprises vascular CT l.propria fused with the periosteum.  It houses seromucous glands as well as lymphoid elements.  The respiratory epithelial lining is similar to that of the nasal cavity,  Numerous ciliated columnar cells whose cilia sweep the mucus layer toward the nasal cavity.  Play a role in the nature of the sounds produced  Voice changes during a cold due to the increased mucus lining. Transmission Electron Microscopy (TEM) Scanning Electron Microscopy (SEM) Clinical Correlation: Primary Ciliary Dyskinesia CILIARY BEATING  Begins at the choana and extends to the opening of the larynx. 1. The superior nasopharynx  lined by a respiratory epithelium 2. The middle oral pharynx  lined by a stratified squamous epithelium 3. The inferior laryngeal pharynx  lined by a stratified squamous epithelium  The l.propria is composed of a loose to a dense, irregular type of vascularized CT  Seromucous glands and lymphoid elements  The l.propria of the posterior aspect houses the pharyngeal tonsil  An unencapsulated collection of lymphoid tissue * Accumulations of lymphoid tissues surrounding the openings of digestive and respiratory passages form WALDEYER’s RING (tonsils) resim  Situated between the pharynx and the trachea  Rigid, short, cylindrical tube  4 cm in length / ~ 4 cm in diameter  Responsible for  Phonation  Preventing the entry of food and fluids into the RS  Pseudostratified ciliated columnar epithelium  Except on the superior surfaces of the epiglottis and vocal folds Stratified squamous nonkeratinized epithelium  Cilia of the larynx beat toward the pharynx,  Transporting mucus/trapped particulate matter to be expectorated/ swallowed  Supported by a set of complexly shaped cartilages: 1. Hyaline cartilages (unpaired thyroid and cricoid cartilages and inferior aspect of the paired arytenoids) 2. Elastic cartilages (unpaired epiglottis, paired corniculate and cuneiform cartilages, and superior aspect of the arytenoids)  Cartilages  connected to one another by ligaments  Their movements  controlled by intrinsic and extrinsic skeletal muscles  from 3 4 arch  Flexible flap of tissue, consisting of central elastic cartilage, covered by mucosa on both side.  During swallowing, positioned horizontally, closes off the upper entrance to the larynx.  Swallowing pushes it back across the opening of the larynx so that the posterior surface is folded down and food passes across the anterior surface  During respiration, stands straight up in the vertical position, permitting the flow of air  Anterior/lingual - stratified squamous/non-keratinized Posterior/pharyngeal - pseudostratified columnar ciliated  Is a tube, 12 cm in length, 2 cm in diameter.  Begins at the cricoid cartilage of the larynx.  Ends when it bifurcates to form the 1˚ brochi. 1. Mucosa 2. Submucosa 3. Adventitia  C-rings  Respiratory epithelium  Pseudostratified columnar ciliated ep.  Lamina propria  Subepithelial CT  Elastic fibers  The bundle that seperates mucosa and submucosa 1. Goblet cells  ~30% of total cells  Produce musinogen 2. Ciliated columnar cells  ~30% of total cells  Move the mucus via ciliary action 3. Basal cells  ~30% of total cells  Undifferantiate cells considered to be SCs 4. Brush cells  Small granule-mucous cells  Tall microvilli 5. Serous cells  Electron-dense secretory product 6. DNES cells (Kulchitsky cells)  Monitor the O2 and CO2 levels  Dense irregular fibro-elastic CT  Mucous and seromucous glands  Lymphoid elements  Rich blood and lymph supply  Fibro-elastic CT  Anchores the trachea to the adjacent structure  eusophagus, CT of the neck etc.  Most prominent feature; C-rings !  10 to 12 horse-shoe-shaped hyaline cartilage rings  Open ends face posteriorly and connected to each other by smooth muscle  The trachealis muscle  Trachea is rounded anteriorly but flattened posteriorly  The perichondrium of each C-ring is connected to the those of other rings  Provides the flexibility and permits the elongation during inspiration!  The respiratory ep. undergoes reversible alterations Metaplasia  Increase the number of goblet cells relative to ciliated cells.  Chronically exposure to irritants e.g. cigarette smoke and coal dust  The increased number of goblet cells produces a thicker layer of mucus to remove the irritants, but the reduced number of cilia retards the rate of mucus elimination, resulting in congestion.  Moreover, the seromucous glands of the l.propria and submucosa increase in size, forming a more copious secretion.  A few months after the elimination of the pollutants, the cell ratio returns to normal (1:1) and the seromucous glands revert to their previous size. DOI - 10.1164/rccm.201306-1181OC  Begins at the bifurcation of the trachea.  Composed of airways located outside and inside of the lung. 1. Outside  1˚ bronchi  Extrapulmonary bronchi 2. Inside  Intrapulmonary bronchi  Bronchioles  Respiratory bronchioles  Identical to that of the trachea.  Except that the 1˚bronchi are smaller in diameter  The walls are thinner.  Each primary bronchus accompanied by  The pulmonary arteries  Veins  Lymph vessels  The right bronchus is straighter than the left one!  Right bronchus trifurcates  Left bronchus bifurcates  bronchi do not have c ring but irreqular  Each intrapulmonary bronchus hayline cartilage plates. serves a lobe of the lung.  Similar to 1˚ bronchi, with the following expectations;  C-rings are replaced by irregular plates of hyaline cartilage that completely surround the lumina of the bronchi.  Thus these airways do not have a flattened region  completely round  The smooth muscle is located at the interface of the fibroelastic lamina propria and submucosa as 2 distinct layers.  Bronchioles are considered the 10th to 15th generation of dichotomous branching of the bronchial tree  Less than 1 mm in diameter  Supplies air to a pulmonary lobule.  Bronchioles possess no cartilage  The epithelial lining of bronchioles ranges from ciliated simple columnar with occasional goblet cells in larger bronchioles to simple cuboidal (many with cilia) with occasional Clara cells and no goblet cells in smaller bronchioles.  The lamina propria of bronchioles has no glands; it is surrounded by a loose meshwork of helically oriented smooth muscle layers.  which one of below is wrong bronchus has clara cells Bronchus Bronchioles  Glands  Glands  Cartilage  Cartilage  Goblet cells  Goblet cells  Spirally arrenged smooth  Thick smooth muscle layer muscle layer  Highly folded mucosa  Folded mucosa  Simple columnar/cuboidal cells  Ciliated pseudostratified columnar cells  Presence of Clara cells  Many elastic fibres  Columnar cells with dome-shaped apex that have short, blunt microvilli.  Clara cells are believed to protect the bronchiolar epithelium by lining it with their secretory product.  Produce a surfactant-like material that reduces the surface tension of bronchioles and facilitates the maintenance of their patency.  Moreover, Clara cells divide to regenerate the bronchiolar epithelium.  Terminal bronchioles form the smallest  The most distal region of the conducting portion of the RS  Supply air to lung acini, subdivisions of the lung lobule.  Epithelium  Clara cells and cuboidal cells, some with cilia.  The narrow l.propria  Fibroelastic CT and is surrounded by one or in terminal two layers of smooth muscle cells. bronchioles we still have smooth * Branch to give rise to respiratory bronchioles. muscle