1.5S_Respiratory_Histology.pptx

Respiratory Histology Tissue? What tissue?... I am just full of lung s air Function and Structure are Related Introduction to Microscopic Anatomical Structure as a basis of Function Learning Objectives: 1. Be able to distinguish between the conducting (i.e., airway) and respiratory (gas exchang...

Respiratory Histology Tissue? What tissue?... I am just full of lung s air Function and Structure are Related Introduction to Microscopic Anatomical Structure as a basis of Function Learning Objectives: 1. Be able to distinguish between the conducting (i.e., airway) and respiratory (gas exchange) regions of the respiratory system based on histological structure and relate that structure to the function of these regions. 2. Describe and detail how the regional functional specification of the respiratory system is reflected in the changing distribution of cell types along the tracheobronchial 'tree.' 3. Identify the glandular elements within the tracheobronchial tree and describe their function. 4. Identify the morphology of the larynx and vocal folds and describe the histological differences between the true and false vocal cords. 6. Describe the structure of the respiratory membrane with attention to the composition of the alveolar wall, alveolar space, and interalveolar septum. Functions of the Respiratory System • Provide oxygen (O2) to tissue • Eliminate carbon dioxide (CO2) • Regulate the bloods hydrogen ion concentration (pH) – in conjunc with • Make kidneys Noise (Phonation) • Defend against microbes • Filter blood clots originating in venous circulation • Influence arterial concentrations of chemical signals e.g., ANG 2 Review Of Airway Construction Fig 1.4 West’s The tracheobronchial tree contains two types of airways: conducting and respiratory Conducting: not associated with alveoli Conducting airways define the volume of the Anatomic dead space Respiratory: associated with alveoli Respiratory airways define the area for gas exchange The vast majority of space in the lungs is located within the alveoli, surrounding most of the airways. Basic Organization (conducting airways) Epithelial layer: mostly singular layer. May be pseudostratified in upper airways Columnar Cuboidal all present squamous Connective tissue and glandular tissue in Lamina propria and submucosa “Respiratory epithelium” G Surrounded by serosa and may or may not include cartilage rings or plates ? Submucosal Many celltypes types present present each withRespiratory special Basic Cell in the functions system Type 2 pneumocytes Type 1 pneumocytes Cell/tissue type distribution along tract When viewing this… THINK … about function imparted by each of these cell types or structures airways Epiglott is and Larynx David L. Osborne, EPIGLOTTIS Epiglottis — “lid” of larynx elastic cartilage + mixed seromucous glands two surfaces — two epithelia anterior — oropharynx = stratified squamous posterior — larynx = “respiratory” epithelium images from: Larynx the upper windpipe Between Pharynx and Trachea Rigid short tube preventing entry of food when swallowing Responsible for Phonation Covered by RE except on superior surface of epiglottis or G VF VC VM V LARYNX vocal folds (true & false) false fold = vestibular fold -- more superior of the two folds mucous glands in the lamina propria true fold – aka vocal fold = vocal cords more inferior fold includes skeletal muscle in the lamina propria epithelium abruptly changes. to stratified Multiple squamous (nonkeratinized) due to cartilages in vibration & abrasion of folds in speech larynx Trachea David L. Osborne, TRACHEA general characteristics hollow rigid tube, 1.1 cm x 2.5 cm diameter lume respiratory epithelium n (pseudo-stratified columnar, mucosa with cilia & goblet cells) submuco epithelium rests on a thick BM sa lamina propria (LP) contains thin, fibrous layer elastic fibers condense forms elastic membrane Adventitia with cartilage Respiratory epithelium (Trachea) Pseudostratifi ed ciliated columnar epithelium Goblet cells David L. Osborne, Tracheal Structure- Epithelia 1. Pseudostratified ciliated columnar epithelia 30% Can you see why it is called that? idealized Blow up of picture to drawing the right 2. Basal cells (30% do not reach lumen) stem cells 3. Goblet cells (30%) mucin secreting 4. Brush cells 3% unknown function 5. Serous cells (3%) secrete serous fluid Tracheal Structure: LP and SM and Adventitia LP Mucous and Seromucous glands Blood vessels Loose fibroelastic connective tissue Lymphoid tissue (nodules, lymphocytes and neutrophils Elastic fibers separating mucosa and submucosa Mucous and Seromucous glands Submucos a Adventitia Rich Blood supply Dense irregular connective tissue Lymphoid tissue Fibroelastic connective tissue Hyaline cartilage (C- rings) Bundle of smooth muscle cells bridge the ends of the cartilage Bronchi not trachea C Trachea- rings of cartilage G VF VC VM V Conductive Bronchioles David L. Osborne, Bronchiolar tree David L. Osborne, Bronchial wall (2-9 branches) th Cartilage rings become plates and decrease in thickness and number as they continue to David L. Osborne, Bronchi | Bronchioles C B Tertiary bronchus You should see why there is no gas exchange (Thickness) In this picture, can you see where gas exchange may occur David L. Osborne, Bronchiole s David L. Osborne, Terminal bronchiole terminal bronchiole = most distal portion of the respiratory tree where O2-CO2 exchange can NOT take place. Other features: Epithelium consists of non-ciliated or low columnar cells SMooth muscle near-complete surrounding of bronchiole Connective Tissue = vascular and glandular elements Alveoli adjacent, but NOT continuous with a terminal br. exocrine bronchiolar (i.e., Club) cells Respiratory Bronchioles David L. Osborne, Respiratory bronchioles and alveoli David L. Osborne, onducting to Respiratory transition R C espiratory region (gas exchange). Respiratory Bronchiole = most proximal portion of the respiratory tree where O2-CO2 exchange can occur Alveolar Ducts = open off of RB’s (above); numerous Alveolar Sacs open off of AD-s; 3-10 Alveoli open off of AS-es. X 60; H&E stain SEM (X 180) Respiratory bronchioles alveolar ducts and alveoli David L. Osborne, Alveoli David L. Osborne, Cell types of the alveolus Cell types of the alveolus Cell types of the alveolus (EM) Type 1 Type 2 Type 2 cells again David L. Osborne, Alveolar walls David L. Osborne, Pulmonary vasculaturebronchial a. what is the difference between pulmonary & bronchial aa. pulmonary a. & v. -- the pulmonary circuit: GAS pulmonary EXCHANGE a. a circuit between the R ventricle and L atrium bronchial a. — a “FEEDING” circuit What is the origin of pulmonary bronchial a.? v. Aorta… oxygenated blood TAKEHOME — Bronchial aa. feeds the conducting airway tissue of the respiratory tract pulmonary v. Pleural sac Simple squamous and underlying subserous connective tissue David L. Osborne, Conducting zone Larynx, Trachea, and Bronchial Tree  Within the lumen of the larynx, bilateral projecting vocal folds (or cords) can be placed under variable tension by the underlying vocalis muscles and caused to vibrate by expelled air, producing sounds.  The trachea is completely lined by respiratory epithelium and is supported by C-shaped rings of hyaline cartilage, with smooth trachealis muscles in the posterior opening of the rings.  Left and right primary bronchi enter the two lungs and bifurcate repeatedly into secondary, tertiary, and smaller segmental bronchi with the lung tissue as the bronchial tree.  Bronchi and their branches are lined by respiratory mucosa, with prominent  spiraling bands of smooth muscle and increasingly smaller pieces of hyaline  cartilage.  Branches of the bronchial tree with diameters of 1 mm or less are generally  called bronchioles, which are lined by simple columnar or cuboidal ciliated cells,  with circular smooth muscle but no cartilage.  Terminal bronchioles are the last branches to lack alveoli and are lined David L. Osborne, by simple Respiratory zone  Terminal bronchioles subdivide into two or three respiratory bronchioles, lined by simple cuboidal epithelium and interrupted by scattered squamous evaginations called alveoli, the sites of gas exchange.  A respiratory bronchiole leads to an alveolar duct, which is lined by a continuous series of alveoli, and which ends in a cluster of alveoli called the alveolar sac.  All alveoli are surrounded by sparse connective tissue in interalveolar septa consisting primarily of elastic and reticular fibers and a dense capillary network.  The wall of each alveolus consists of alveolar cells, or pneumocytes, of two types: extremely thin type I alveolar cells and cuboidal type II alveolar cells with surfactant secreting and innate immune properties.  Type II alveolar cells are characterized ultrastructurally by unique cytoplasmic lamellar bodies, large granules with closely stacked layers of membrane involved in surfactant synthesis.  The blood-air barrier allowing gas exchange at each alveolus consists of the thin type I alveolar cell, the thin capillary endothelial cells, and the fused basal laminae of these two cells.  The surfactant material secreted by exocrine club cells and type II alveolar cells is an oily mixture of cholesterol, phospholipids, and surfactant proteins, which forms a film and lowers surface tension in alveoli.  Each lung is covered by visceral pleura, a layer of thin connective and David L. tissue Osborne, The End Questions? Come see me! David L. Osborne, David L. Osborne, David L. Osborne, David L. Osborne, David L. Osborne, David L. Osborne,