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Respiratory A & P Aaron J. Katz, AEMT-P, CIC www.PrehospitalTraining.com/emt Respiratory system -- purpose Bring O2 into the body Produce sufficient ATP Eliminate CO2 from the body Prevent acidosis Respiratory system -- divisions Upper respiratory tract Parts found outside chest cavity Lower respiratory tract Parts found inside chest cavity Upper respiratory tract Air passages of nose Nasal cavities Pharynx Larynx Upper trachea Lower respiratory tract Lower trachea Lungs: Bronchi Bronchioles Alveoli Other divisions Pleural membranes Visceral Parietal Diaphragm Intercostal muscles Nose and Nasal cavities Nose – bones & cartilage Nasal cavities Nasal septum Nasal mucosa Ciliated epithelium Conchae/turbinates Increases surface area of mucosa Warms and moistens inspired air Nose and Nasal cavities Olfactory receptors Paranasal sinuses Lighten the skull Provides resonance for voice Pharynx Nasopharynx Oropharynx Laryngopharynx Nasopharynx Behind nose Soft palate Elevates while eating to prevent food from going up Uvula Adenoid – lymph tissue Pharyngeal tonsils – lymph tissue Eustachean tubes Oropharynx Behind mouth Palatine tonsils On lateral wall – lymph tissue ?? Question ?? What is the main function of tonsils/adenoids? Larygopharynx Most inferior portion of pharynx Opens anteriorly into larynx Opens posteriorly into esophagus Swallowing reflex causes contraction of oro/laryngopharynx muscles Why is this important? Larynx – “Voice Box” Voice production Conducts air to/from pharynx to/from trachea Composed of 9 pieces of cartilage Connected by ligaments Prevents collapse of larynx Tony Kubek Ciliated epithelium – except for vocal cords Larynx – “Voice Box” Thyroid cartilage – “Adams Apple” Epiglottis – on top of glottis largest cartilage of larynx Uppermost cartilage of larynx Leaf shaped covering of trachea Prevents food from entering trachea Hyoid bone supports epiglottis Larynx – “Voice Box” Vocal cords Glottis Opening on either side of vocal cords Breathing On either side of glottis Vocal cords move to side Talking Vocal cords pulled to center Exhaled air causes vibration speech Larynx – “Voice Box” Controlled by vagus/accessory cranial nerves arytenoid cartilage Attach to vocal cords Pivoting arytenoids move cords Arthritis of arytenoids? Corniculate “Corn kernel” Covers arytenoids ?? Questions ?? What does “bearing down” accomplish? When would one want to do this? Why are the positions of the arytenoids important? Trachea 4 – 5” Made up of 16-20 C-shaped cartilages Keeps trachea open Opening is posterior – allows for expansion of esophagus with food Ciliated epithelium Top cartilage is cricoid cartilage Completely encloses the trachea Implications? Trachea vs. Esophagus Trachea Esophagus Opening maintained by cartilage Antertior to esophagus Smaller than “open” esophagus Usually closed unless food is inside Posterior to trachea “Open” esophagus larger than trachea Very easy to intubate the esophagus – with disasterous results Bronchial Tree Right/Left “primary bronchi Bronchioles Right – 3 branches 3 lobes Left – 2 branches 2 lobes No cartilage to maintain lumen Implications for asthmatics Alveoli “where the action takes place” Alveoli Clusters of elastic tissue One cell thick Surrounded by pulmonary capillaries Tissue fluid on internal surface Pulmonary surfactant Potential problem: surface may stick to itself – collapsed alveoli Coats tissue fluid Reduces surface tension – preventing collapsed alveoli Hyaline Membrane Disease – Respiratory Distress Syndrome (“RDS”) Lung Tissue Base rests on diaphragm Apex is at the level of clavicle Hilus Indentation on medial surface of lungs Bronchus & pulmonary artery/vein enter lung at the Hilus Visceral pleura Parietal pleura Serous fluid Prevents friction Keeps pleura from separating Ventilation Movement of air to/from alveoli Inhalation Exhilation Under control of medulla and pons Muscles of ventilation Diaphragm External intercostals Pulls ribs upward/outward Inhalation Internal intercostals Pulls ribs downward/inward Exhalation Air pressures Atmospheric pressure: 760mm Hg Intrapleural pressure 756mm Hg “negative pressure” Intrapulmonic pressure Pressure within bronchial tree and alveoli Pressure depends on point within the breathing cycle Inhalation/inspiration An active process Brain detects high levels of CO2 in the blood and sends an “impulse” Medulla phrenic nerves intercostal muscles Diaphragm contracts moves downward Inhalation/inspiration External intercostals pull ribs outward and upward Intrapulmonic pressure decreases below 760mm Hg Air rushes in – until intrapulmonic pressure equals atmospheric pressure Intrapleural pressure becomes more negative ?? Question ?? What’s different about a COPD patient? Exhalation/expiration Passive process in “normal” people Impulses from medulla decrease Diaphragm and external intercostals relax – internal intercostals contract Intrapulmonic pressure rises above 760mm Hg Air rushes out until intrapulmonic pressure equals atmospheric pressure Lung and healthy alveoli recoil to initial shape Respiration Two types External respiration Gas exchange at alveoli/pulmonary capillaries Internal respiration Gas exchange at body tissue/systemic capillaries Diffusion Within the body a gas will diffuse from an area of greater concentration to an area of lower concentration Partial Pressure of Gases The partial pressure (measured in mm Hg) of a particular gas within a mixture of gases is the pressure that the gas exerts Gas may be in gas form or dissolved in a liquid (e.g. blood) “P” – e.g. PO2 means the partial pressure of oxygen a mixture of gasses Typical partial pressures PO2 PCO2 Atmosphere 160 0.30 Alveoli 104 40 Pulmonary blood (venous) Systemic blood (arterial) Tissue fluid 40 45 100 40 40 50 Calculation of partial pressures Pgas = % of gas in the mixture X total pressure For example: PO2 = 21% X 760 = 160mm Hg in the atmosphere Why is this important? What does this have to do with diffusion? Movement of gasses Inspired air in alveoli: High PO2; low PCO2 Blood in pulmonary capillaries: Low PO2; high PCO2 What happens? O2 diffuses from alveoli to pulmonary capillaries CO2 diffuses from pulmonary capillaries to alveoli Life continues nicely! Internal respiration Arterial blood reaching systemic capillaries: High PO2; low PCO2 Body tissues (after production of energy): low PO2; high PCO2 What happens? O2 diffuses from blood to tissues CO2 diffuses from tissues to blood Life continues nicely! Some definitions Tidal Volume (TV): volume inspired in one quiet breath Minute Volume (MV): volume inspired in one minute of quiet breathing MV = RR X TV MV approximately 5 – 6 liters See book for other similar definitions Respiratory Disease Processes Arise from problems with one or more of: Brain’s sensing O2 needs Chest wall movement Blood flow to lungs Air exchange Amount of lung surface area Quality of lung surface area Problems with brain’s sensing O2 needs CO2 retention Head trauma Depressant drugs (e.g. narcotics) Hypo/hyperthermia Stroke Problems with chest wall movement Trauma Rib fractures Flail chest Ruptured diaphragm MAST usage Pregnancy Gastric distention Airway constriction FBAO Asthma, croup, epiglottitis Problems with blood flow to lungs Pulmonary emboli caused by: Blood clots (e.g. DVT) Air Amniotic fluid (explosive delivery) Fat/marrow (long bone fracture) Problems with air exchange Thick alveolar walls (lung diseases) “Water” (A.P.E.) Loss of elasticity (COPD – emphysema) Mucus/pus (pneumonia) Mucus/pus (COPD – chronic bronchitis) Insufficient perfusion (shock) Problems with amount of lung surfaces “Water” (A.P.E., aspiration) Pneumothorax (“atelectasis” – “collapsed lung”) Obstruction Emphysema Gastric distention Problems with quality of lung surfaces A.P.E. Emphysema Pulmonary burns Pulmonary contusions In summary… Items needed for quality respiration: O2 usage Sufficient lung surface area Quality lung surface area Brain function Functioning chest wall Known as the “Fick Principle”