Respiratory System PDF 07.03.2024

RESPIRATORY SYSTEM Lecturer Ceren ERDEM ALTUN [email protected] 07.03.2024 → Must be able to describe the basic wall structure of the airways from the nose to the alveoli. → Must be able to explain the functions of respiratory tract mucosa and mucus. GOALS → Be able to list the layers that mak...

RESPIRATORY SYSTEM Lecturer Ceren ERDEM ALTUN [email protected] 07.03.2024 → Must be able to describe the basic wall structure of the airways from the nose to the alveoli. → Must be able to explain the functions of respiratory tract mucosa and mucus. GOALS → Be able to list the layers that make up the respiratory membrane. → Be able to explain cell types and functions in the alveolar epithelium. RESPIRATORY SYSTEM FUNCTIONS ✓ Transport of oxygen to cells, removal of CO2 ✓ Heating of inhaled air (by the veins near the surface and by turbulence in the turbinates(conchae) ✓ Humidification of inhaled air (with serous glands) ✓ Removal of particles from inhaled air (with mucus and kinocilium) ✓ Immune protection (with lymphoid Tissue and macrophages) ✓ Olfactory (olfactory epithelium) ✓ Voice creation (real and fake vocal cords) ANATOMY OF THE RESPIRATORY SYSTEM CONDUCTING PORTION RESPIRATORY PORTION ❑ The respiratory system is functionally examined in 2 parts; 1) CONDUCTING PORTION - nasal cavity - nasopharynx (throat) - larynx (larynx) - trachea - bronchi - bronchiole and terminal bronchiole → It cleans and moistens the inhaled air and creates a passage through which air travels to and from the lungs. → Cartilage, elastic and collagen fibers, and smooth muscles in the conductor section provide the necessary bendability, extensibility and structural support ❑ The respiratory system is functionally examined in 2 parts; 2) RESPIRATORY PORTION - respiratory bronchioles - alveolar ducts - alveoli → The part where gas exchange occurs between air and blood. →Alveoli; They are sac-like structures that make up a large part of the lungs, where O2 and CO2 exchange between inhaled air and blood takes place. NASAL CAVITY Nasal skin is a keratinized stratified squamous epithelium that enters through the nostrils and progresses to the vestibule. This skin contains sweat glands, sebaceous glands, and wet and thick nasal hairs that trap large particles in the inhaled air. In the vestibule, the epithelium loses its keratin structure and turns into the typical pseudostratified columnar ciliated epithelium of the respiratory system before entering the nasal cavities. The front part of the nose is supported by cartilages, and the back part is supported by cartilages and bones. Nasal pits are located within the skull as two chambers separated by the nasal septum. There are 3 bony protrusions called turbinates (conchae) on the side wall of each chamber. The middle and lower turbinate are covered with RESPIRATORY EPITHELIUM, the roof of the nasal fossa and the upper turbinate are covered with specialized OLFACTORY EPITHELIUM NASOPHARYNX The nasal cavity is adjacent to the nasopharynx from behind via the turbinates. Turbinates(conchae); They increase the surface area and contribute to the heating and humidification of inhaled air by creating turbulence. 1) VESTIBULE It is the part of the nose that opens to the outside environment. It is lined with stratified squamous epithelium, which is a continuation of the facial skin. It contains numerous VIBRISSA (nasal hairs) that trap large particles entering with inhaled air. The secretions of the sebaceous glands it contains also help capture particles. at the point where the vestibule ends, the epithelium becomes thinner and turns into pseudostratified columnar ciliated epithelium, which is specific to the respiratory region. MIDDLE AND LOWER CHONCAE RESPIRATORY EPITHELIA UPPER CHONCAE OLFACTORY EPITHELIA 2) RESPIRATORY PORTION It constitutes the majority of the nasal cavity volume. 2) RESPIRATORY PORTION pseudostratified columnar ciliated epithelium Basal membrane LAMINA PROPRIA MUCOSA = EPITHELIA + LAMINA PROPRIA EPITHELIA LAMINA PROPRIA →It consists of loose connective tissue with a rich vascular network. → The arrangement of the veins ensures that the inhaled air is heated by the flowing blood. These veins become overfilled and leak during colds, allergic reactions or viral infections. Lamina propria swells with fluid accumulation. As a result, swelling of the mucous membrane limits air passage and breathing difficulties occur. →The mucus layer produced by the glands and goblet cells traps airborne particles. →IgA secreted from plasma cells in the lamina propria plays a role in local defense. THERE ARE 5 TYPES OF CELLS IN THE RESPIRATORY EPITHELIA AND EACH SIT ON THE BASAL MEMBRANE!!! 1. 2. 3. 4. 5. Columnar ciliated cells; is the most abundant, 250-300 hairs on the apical surface Goblet cells; more dense in some areas, nucleus located basally, secretory granules apically Brush cells; a small number of prismatic cells, vestigial microvilli, and chemosensory (chemical sensing) receptors. Kulchitsky cells; cells of the neuroendocrine system containing dense granules Basal cells; Stem and precursor cells capable of mitosis G: Goblet cell arrow: mucus accumulations 3) OLFACTOR PORTION THERE ARE 3 TYPES OF CELLS IN THE OLFACTOR EPITHELIA!!! 1. Olfactory receptor cell 2. Supporting cell 3. Basal cell OLFACTORY NEURON → bipolar neurons → Their nuclei form an irregular row in the central part of the epithelium.. → The extensions facing the apical (lumen) are dendrite tips. → Long cilia extend from the basal bodies, which are immobile but serve to increase the surface area for chemoreceptors. SUPPORTING CELL →They are long thin prismatic cells extending from basal to apical. →The nuclei at the top of the epithelium are the support cell nuclei. →There are plenty of microvilli on their surface. →They provide mechanical and metabolic support to olfactory cells. →Proteins that bind odor molecules are secreted from these cells. BASAL CELLS → They are small, round or coneshaped cells close to the basal lamina. → Every 2-3 months they replace olfactory neurons and, less frequently, supporting cells. BASAL CELLS The Lamina Propria of the olfactory epithelium contains the olfactory glands, which are large serous glands that facilitate the entry of new odorants by providing a constant flow of fluid around the olfactory hairs; Bowman’s gland Supporting cells Olfactory epithelia Lamina propria SC: supporting cell OC: olfactory cell BC: basal cell NASOPHARYNX NASOPHARYNX The nasal cavities open into the nasopharynx, the first part of the pharynx. The nasopharynx continues caudally with the oropharynx (throat). This structure opens into the larynx and esophagus. The epithelium is a respiratory epithelium similar to the nasal cavity epithelium. LARYNX It is a short (4cmx4cm) air passage located between the pharynx and trachea. Hard wall; Large cartilages (thyroid, cricoid, arytenoid) are hyaline type. Small cartilages (epiglotte, cuneiform, corniculate) are elastic type. Cartilages in the structure; They play a role in keeping the airway open, preventing food from entering the trachea, and producing sound. LARYNX G: seromucous gland LV: larynx vestibules VF: vestibüler fold V: ventricle VC: vocal cords VM: striated vocalic muscles EPIGLOTTIS It is a flat structure that protrudes from the upper part of the larynx. It prevents swallowed food or liquid from entering the trachea. EPIGLOTTIS → The side facing the tongue is stratified squamous epithelium; It turns into respiratory epithelium at different points of the laryngeal surface. There are mixed serous and mucous glands in the lamina propria beneath the epithelium. TRACHEA It contains approximately 12 C-shaped hyaline cartilage rings. It strengthens the wall and ensures that the tracheal lumen remains open. The open ends of the cartilage rings are directed towards the esophagus on the back side of the trachea, and they are joined by a smooth muscle bundle called tracheal muscle and fibroelastic tissue attached to the pericondrium. The entire organ is surrounded by adventitia. The trachea, 10–12 cm long in adults, is lined with typical respiratory mucosa in which the lamina propria contains numerous seromucous glands that produce watery mucus. The trachea is completely lined with respiratory epithelium and supported by C-shaped rings of hyaline cartilage between the submucosa and adventitia, strengthening the wall and keeping the tracheal lumen open. It is a tube with 3 layers: mucosa, submucosa and adventitia. Divides into 2 primary bronchi SUBMUCOSA MUCOSA LAMINA PROPRIA BASAL MEMBRANE RESPIRATORY EPITHELIUM LAMINA PROPRIA It is loose connective tissue. There are many fibroblasts, lymphocytes, plasma cells, mast cells, eosinophils and abundant blood vessels. Collagen and elastic fibers condense in their depths and form a fibroelastic region. SUBMUCOSA It has the feature of loose connective tissue. There are many seromucous glands CARTILAGE: The submucosa continues with the perichondrium of the underlying hyaline cartilage. ADVENTITIA It is loose connective tissue that contains blood vessels and nerves. MUCOSA SUBMUCOSA ADVENTITIA BRONCHIAL TREE AND LUNG The trachea branches and divides into 2 to form the primary bronchus. (accompanied by arteries, veins and lymph vessels) After entering the lungs, the bronchi divide into 3 secondary bronchi in the right lung and 2 secondary bronchi in the left lung.. The secondary bronchi branch again and form the tertiary bronchi. Each of the tertiary bronchi divides into smaller branches and forms the bronchopulmonary segment. This structuring; It allows surgical resection of diseased lung tissue without damaging adjacent healthy tissue. The diameter of the tertiary bronchi gradually decreases and they branch to form bronchioles. Each bronchiole enters the pulmonary lobule and forms 5-7 terminal bronchioles and continues as respiratory bronchioles. Cartilaginous rings turn into cartilage plates as the diameter of the bronchi decreases. When it reaches the bronchioles, it disappears. BRONCHI E: respiratory epithelia SM: smooth muscle C: hyaline cartilage B:seromucous glands V: vein SEGMENTAL BRONCHI BRONCHIOLES There is tight connective tissue and smooth muscle, but there are no glands and cartilage structures. In larger bronchioles the epithelium is still pseudostratified ciliated columnar epithelium. However, as you move towards the terminal bronchioles, which are the last parts, the size and complexity decrease and the epithelium turns into single-layered columnar and singlelayered cuboidal epithelium. BRONCHIOLES In very small bronchioles, the epithelium descends and turns into a singlelayered fibrillar cuboidal epithelium. Several layers of smooth muscle, indicated by arrows, make up the bulk of the wall. TERMINAL BRONCHIOLES They are the last parts of the air conduction system before the gas exchange zones. It contains 1 or 2 layers of smooth muscle cells surrounded by connective tissue. The epithelium consists of cuboidal epithelial cells with cilliated and low prismatic cells (clara cells) that do not contain cilia. TERMINAL BRONCHIOLES CLARA CELLS: Cells that do not contain cillia, have a domeshaped apical surface, and have secretory granules in their cytoplasm. CLARA CELLS; Clara - secretes surfactant, which reduces surface tension and helps prevent bronchiolar collapse -Secretion of antimicrobial peptides and cytokines for local immune defense - Depending on the damage, it multiplies by mitosis and replaces other cells, showing stem cell characteristics. Clara RESPIRATORY BRONCHIOLES Each terminal bronchiole divides into two or more respiratory bronchioles containing sac-like alveoli. The respiratory bronchiolar mucosa is the same as the terminal bronchioles, except for the alveoli where air exchange occurs. Respiratory bronchioles open into the alveolar duct. The mucosal epithelium contains clara cells and cilliated cuboidal cells. The alveolar canal extending to the alveoli is lined with flat cells. There is a thin series of smooth muscle cells in the Lamina propria at the entrance of each alveolus. ALVEOLIES They are sac-like structures with a diameter of 200 μm, consisting of respiratory bronchioles, alveolar ducts and alveolar sacs. The total area of the inner surface of the lung in an adult human is 75 m2 and contains 200 million alveoli. Each alveolus is a small round pocket with one side opening into the alveolar sac/duct. Alveolar epithelium contains 2 types of cells. 1) Type-I alveolar cell; 90% of total cells. squamous epithelial 2) Type-II alveolar cell; 10% of total cells. Polygonal shaped, with microvilli. It produces surfactant. Type-I alveolar cell; They are very thin (25nm), flat cells that line the alveolar surface. Connected to each other by occlusive junctions and desmosomes Pinocytic vesicles located in the thin cytoplasm may play a role in surfactant turnover and removal of small airborne particles. Type-II alveolar cell; Cuboidal cells interspersed between type 1 cell, interconnected by occlusive junctions and desmosomes, protruding into the alveolus They are cells that derive from the same origin as type 1 and sit on the same basement membrane. It both renews itself after damage and forms a precursor cell source for Type 1 cell. BLOOD-AIR BARRIER Air in the alveoli is separated from capillary blood by the blood-air barrier. COMPONENTS OF BLOOD-AIR BARRIER; - 2 or 3 very thin flat cells covering the inside of the alveolus - Fused basal lamina of capillary endothelium and alveolar epithelium - thin endothelial layer of capillaries Dust cells (alveolar macrophages) are found within the alveoli and in the alveolar septum. They phagocytose particles and damaged erythrocytes that reach the alveoli through the air.