Chapter 23: Part 1 - The Respiratory System

Part 1 (The Respiratory System) Chapter 23 Organization of the Respiratory System · The respiratory tract is organized in two ways: ① Structurally ↳ upper respiratory tract: nose, nasal cavity, sinuses, pharynx ↳ lower respiratory tract: larynx, trachea, bronchi, bronchioles, alveoli ② Functionally ↳ conduction: air to and from the lungs, filters, warms, and humidifies air ↳ respiration: gas exchange with alveoli Upper Respiratory Tract · Functions: ↳ to warm, humidify, and filter air ↳ to defend against pathogens and noxious substances · External nose: ↳ nares (nostrils), nasal septum, coarse hairs to trap foreign particles, built on cartilaginous framework · Internal nose: ↳ nasal cavity, internal nares (communicate with pharynx) ↳ 3 shelves along lateral walls: - superior nasal concha - middle nasal concha - inferior nasal concha Nasal Concha · ridges in the nasal cavity that create turbulence when you breathe · increases the likelihood of particles getting trapped or binding to receptors for smell · allows time for air to be warmed, humidified, and filtered Epithelia of Upper Respiratory Tract · majority of the upper respiratory tract is lined with pseudostratified ciliated columnar epithelium ↳ secretes mucous to help moisturize and trap foreign particles ↳ cilia sweeps the mucous towards the pharynx where it is swallowed · mucociliary escalator · part of the Respiratory Defense Mechanism · lamina propria: the underlying layer of areolar tissue that contains the glands, highly vascular (nose bleeds) Paranasal Sinuses · air-filled cavities in ethmoid, sphenoid, frontal, and maxillary bones (paired) · lined with mucous membranes, mucous production increases when introduced to noxious vapors, large quantities of dust and debris, allergens, or pathogens · open into the nasal cavity · Functions: resonating chambers for voice, decreases weight of skull Pharynx · common passageway connecting the nose, mouth, and throat · functions: ↳ passage for food and air ↳ allows for sound resonation ↳ contains tonsils · has three distinct regions: ↳ nasopharynx ↳ oropharynx ↳ laryngopharynx Regions of Pharynx · Nasopharynx (air only) ↳ Eustachian tubes (air pressure in ear) Larynx · functions ↳ production of sound (voice box) ↳ pseudostratified ciliated columnar epithelium ↳ conduction of air into lower respiratory tract · Oropharynx (air and food) ↳ pharangeal arch and uvula ↳ stratified squamous epithelium · Laryngopharynx (air and food) ↳ protection of airway from swallowed material (epiglottis) · location ↳ entrance to trachea and esophagus ↳ stratified squamous epithelium ↳ below pharynx ↳ only air should pass through ↳ respiratory and digestive tracts diverge Unpaired Cartilages of the Larynx · Thyroid Cartilage ↳ contains laryngeal prominence (adams apple) Paired Cartilages of Larynx · Arytenoid cartilages ↳ hyaline cartilage ↳ hyaline cartilage · Corniculate cartilages ↳ encircles the trachea · Cuneiform cartilage · Cricoid Cartilage ↳ hyaline cartilage · Epiglottis ↳ closes over the glottis when swallowing food ↳ elastic cartilage ↳ hyaline cartilage ↳ elastic cartilage · Functions: ↳ helps open and close the glottis ↳ involved in sound production Trachea · Tough flexible tube, extends from larynx C6 to T5 and then splits into the 2 main bronchi · composed of: ↳ mucosal layer: pseudostratified columnar with cilia and goblet (mucous) cells ↳ submucosa: loose connective tissue ↳ hyaline cartilage: 15-20 incomplete rings (C-shaped) · Why are the rings C-shaped? ↳ to allow the esophagus to expand when swallowing large chunks of food Bronchi · composed of: ↳ cartilage - incomplete ring ↳ pseudostratified ciliated columnar epithelium ↳ smooth muscle - complete ring ↳ primary bronchi enter the hilum of each lung - hilum: depression through which the bronchi, nerves, blood vessels, lymphatics enter/leave the lung · Carina: the section where the trachea divides in to the primary bronchi ↳ covered in very sensitive mucous membrane The Bronchial Tree ① Primary bronchi · branch from trachea (one to each lung) ② Secondary bronchi (lobar bronchi) · supplies each lobe of lungs · left lung: has 2 lobes and 2 secondary bronchi · right lung: has 3 lobes and 3 secondary bronchi ③ Tertiary Branch · Supplies each bronchopulmonary segment · divides into bronchioles ④ Bronchioles ⑤ Terminal bronchioles ⑥ Respiratory bronchioles ⑦ Alveolar ducts ⑧ end in alveolar sacs made of alveoli · As you go down the structures get smaller, and the amount of cartilage decreases and the amount of smooth muscle increases · ANS controls bronchodilation and bronchoconstriction ↳ sympathetic activation → bronchodilation → breathe more ↳ parasympathetic activation → bronchoconstriction → just a lil! Alveolar Cells · Type I alveolar cells ↳ simple squamous cells (pneumocytes) where gas exchange occurs · Type II alveolar cells ↳ aka septal cells ↳ secrete alveolar fluid containing surfactant - for moisture, to reduce surface tension and prevent collapse Lungs (structures and terms to know) · apex and base of lungs · costal surface · mediastinal surface (medial surface nearest to mediastinal structures) · diaphragmatic surface (on the diaphragm) · Cardiac notch (makes space for heart) · Fissures: ↳ Oblique & horizontal fissures in right lung results in three lobes ↳ Oblique fissure only in left lung produces two lobes Parietal Pleura (covers body wall) Intrapleural Space Visceral Pleura (covers lung) (pleural fluid/serous fluid) ↳ lubrication to prevent friction Thoracentesis: a test of pleural fluid to look for abnormal cells and pathogens Pleurisy: inflammation in the pleural space Pleural effusion: When fluid enters the pleural space (effects gas exchange) Pneumothorax: penetrating chest injury when air enters and changes pressures, causing the lungs to collapse Pulmonary embolism: when a clot moves to the lungs (effects gas exchange) Blood Supply to the Lungs · primary function of respiratory tract: to remove carbon dioxide from deoxygenated blood and replace it with oxygen · Process: ↳ deoxygenated blood is returned to the heart via the venous system ↳ deoxygenated blood is then carried via the pulmonary arteries to alveolar capillaries where gas exchange happens ↳ pulmonary veins carry oxygenated blood back to the left side of the heart to be distributed to the tissues of the body · Remember: the lungs also require their own blood supply (from the bronchial arteries) blood air barrier/respiratory membrane: what gases have to go through for gas exchange ↳ 3 layers: - alveolar cell - capillary cell - basement membrane · pneumonia: liquid in the lungs that increases the distance required for gas exchange, so you have to work harder to get oxygen Respiration · general function: to obtain O2 for use by the body's cells and to eliminate CO2 produced by those cells · involves two separate but related processes: 1. External Respiration: ↳ processes involved in the exchange of O2 hypoxia: low oxygen to tissues body's interstitial fluids (outside air → fluids) (quickly leads to cell death) and CO2 between the external environment and the 2. Internal Respiration: ↳ diffusion of O2 and CO2 between the interstitial fluids and the cells (interstitial fluid → cells) anoxia: no oxygen to tissues Pulmonary Ventilation · refers to the physical movement of air into and out of the lungs (fancy term for breathing) · maintains alveolar ventilation (movement of air into and out of alveoli; prevents build-up of carbon dioxide) · air moves into and out of respiratory tract due to the pressure gradient inside the lungs vs. atmospheric pressure outside · Atmospheric Pressure (atm): weight of earths atmosphere (pressure gradients) · Boyle's Law: the relationship between pressure and volume ↳ large volume = low pressure → air enters lungs ↳ low volume = high pressure → air does not enter lungs Respiratory Muscles & Pulmonary Ventilation · Respiratory muscles ↳ muscles of pulmonary ventilation (breathing): - diaphragm - external intercostals ↳ exhalation is passive (no muscles required) · Diaphragm ↳ contracts (lowers) to cause inhalation - increases volume, pressure decreases, air moves in ↳ relaxes (raises) to cause exhalation - decreases volume, pressure increases, air moves out · External intercostals: elevates the ribs to aid in inhalation