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WEEK 8- Respiratory System.pdf

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Humber College
BIOL 271

Respiratory System Respiratory System Anatomy upper respiratory tract superior to vocal cords lower respiratory tract inferior to vocal cords Nose: External Portion nasal bones and hyaline cartilage covered with skin, lined with mucous membrane openings called external nares cavity within the skull inferior to nasal bone, superior to mouth functions: warms, moistens air filters air gives resonance to voice Nose: Internal Portion roof formed by ethmoid and sphenoid bones floor formed by maxilla and palatine bone lined with pseudo stratified ciliated columnar epithelium with goblet cells (respiratory epithelium/membrane) olfactory epithelium houses receptors for smell conchae (turbinate bones) bony projections on lateral walls of internal nose internal nares (choanae) openings to pharynx Paranasal Sinuses cavities in the frontal, sphenoid, ethmoid, and maxillary bones lighten skull gives resonance to voice Pharynx funnel-shaped tube about 13 cm long extend from internal nares to cricoid cartilage functions: passageway for air and food resonating chamber fror speech production tonsils (lymphatic tissue)in the walls protect against choking potential problem: air and food crossing and mixing stomach or lungs 3 regions: nasopharynx from internal nares to soft palate openings for auditory (Eustachian) tubes in lateral walls adenoids (pharyngeal tonsils) in roof passage way from only air lined with respiratory epithelium oropharynx from soft palate to level of hyoid bone opening to (fauces) palatine and lingual tonsils passageway for food and air lined with stratified squamous epithelium laryngopharynx from level of hyoid bone to cricoid cartilage ends inferiorly as esophagus passageway for food and air lined with stratified squamous epithelium Larynx C4 to C6 consists of 3 single, 3 paired cartilages structures: hyoid bone thyroid cartilage (Adam's apple) cricoid cartilage (ring of cartilage attached to trachea) epiglottis (leaf-shaped elastic cartilage) covers glottis during swallowing cuneiform cartilages elastic cartilage anterior to corniculates support vocal folds and corniculate cartilages elastic cartilages at tip of each arytenoid artenoid cartilages hyaline cartilage sit atop cricoid move vocal cords Vocal Cords ventricular fold false vocal cord vocal fold true vocal cord inferior to false cords attached to arytenoid cartilages Voice Production true vocal cords consist of __ and elastic ligament (vocal ligament) muscles of the larynx move cartilages and stretch vocal cords sound produced when vocal cords vibrate as air moves through glottis pitch depends on length and tension of cords >> (deeper voice in males due to longer, thicker vocal cords) volume depends on force of air Trachea 12 cm, long, 2.5 cm, in diameter from larynx to T5 anterior to the esophagus histology: lumen goblet cell, respiratory epithelium (mucosa) basement membrane lamina propria contains elastic and reticular fibres; blood supply epithelium provides protection against dust cilia move particles trapped in mucus upward towards esophagus "mucous elevator" structure: wall: 16-20 C-shaped rings of hyaline cartilage (prevent collapse) connected by elastic annular ligaments (flexible) posterior wall (facing esophagus) contains tracheal is m. bifurcates into R and L primary bronchi internal ridge at bifurcation called the carina (very sensitive, irritation triggers reflex) The Bronchial Tree consists of primary bronchi and 13 generations of their branches 300,000 bronchioles (smallest branch) in each lung trachea — primary bronchi — secondary bronchi — tertiary bronchi — bronchioles — alveoli Bronchi and Bronchioles primary bronchi supply each lung secondary bronchi supply each lobe to the lungs (3 right and 2 left) tertiary bronchi supply each bronchopulmonary segment (smaller lobes, 10 in each lung) terminate in bronchioles progressive change in lining from ciliated columnar epithelium in bronchi, to conciliated simple cuboidal in terminal bronchioles bronchi walls supported by incomplete cartilage rings incomplete rings of cartilage in smaller tubes replaced by rings of smooth muscle, then connective tissue no cartilage in terminal bronchioles so muscle spasm can completely close airways (asthma) terminal bronchioles end in respiratory bronchioles (alveoli in walls) Pleural Membranes visceral: covers outer surface of lungs parietal: lines ribcage, covers diaphragm pleural cavity: space between visceral and parietal pleura Gross Anatomy of Lungs apex, costal surface, base, hilus (vessels and bronchi entrance into lungs; forms root of lung) oblique and horizontal fissures lobules small compartments wrapped in elastic CT contain lymphatic vessel, arterioles, venule, branch of a terminal bronchiole structures within: elastic CT, visceral pleura terminal bronchiole (no alveoli in wall) respiratory bronchiole (alveoli in wall; simple squamous) alveoli (branch from alveolar ducts) alveolar ducts (branch from respiratory bronchioles) alveolar sac (alveoli with a common opening) lymphatic vessel pulmonary venule pulmonary capillaries pulmonary arteriole Alveolar Cell Types type I alveolar cell simple squamous epithelium site of gas exchange type II alveolar cell (Septal cell) microvilli on free surface secrete surfactant (decreases surface tension within alveoli) alveolar macrophage (dust cell) wandering macrophage engulfs debris Respiratory Membrane 0.5 um thick site of alveoli-blood gas exchange 4 layers: type I alveolar epithelium alveolar epithelial basement membrane capillary wall basement membrane capillary endothelium Respiratory System Physiology Processes involved in gas exchange: pulmonary ventilation external respiration diffusion gas transport internal respiration cellular respiration Ventilation "breathing" or "respiration" movement of gases in and out of the lungs lungs have no means of moving by themselves they move only in response to changes in pressure in the intrapleural and intrapulmonary spaces pleural membrane moves lungs with thoracic cavity movement (water between slides) Pulmonary Ventilation air moves into lungs when pressure inside lungs is less than atmospheric pressure air moves out of the lungs when pressure inside lungs is higher than atmospheric pressure atmospheric pressure = 1 atm (atmosphere) or 760 mmHg at 0 Kelvin Gas Pressures atmosphere pushes mercury down in dish, which pushes mercury up the tube measure how far up the tube mercury moves (mmHg) higher altitude = less atmospheric pressure = fewer mmHg 0mmHg ≠ 0 pressure Intrapulmonary Pressure pressure within the lungs at rest=atmospheric (760mmHg at sea level) gases move as a result as a result of pressure differences between the atmosphere and the intrapulmonary space Boyle's Law if temperature is held constant, the pressure of a gas varies inversely with its volume ex: pushing syringe: volume decreases while pressure
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