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Respiratory System Breathe in. Breathe out. Any questions? Outline • Functions of the respiratory system • Organs of the respiratory system • Process of breathing Functions of the respiratory system Functions of the respiratory system 1) Fill and empty the lungs 2) Oxygenate and remove CO2 from blood 3) Oxygenate and remove CO2 from tissues Functions of the respiratory system 1) Fill and empty the lungs Ventilation 2) Oxygenate and remove CO2 from blood External respiration 3) Oxygenate and remove CO2 from tissues Internal respiration Organs of the respiratory system Organs of the respiratory system The Airway Organs of the respiratory system The Airway • Other organs (Not the airway) Organs of the respiratory system The Airway • Nasopharynx • Larynx • Trachea • Bronchi • Lungs Upper Respiratory tract Lower Respiratory tract Organs of the respiratory system The Airway • Nasopharynx • Larynx • Trachea • Bronchi • Lungs • Other organs (Not the airway) Organs of the respiratory system The Airway • Nasopharynx • Larynx • Trachea • Bronchi • Lungs • Other organs (Not the airway) • Oral pharynx • Vocal cords • Epiglottis • Ribs / intercostal mm. • Diaphragm • Pleura The Airway--Nasopharynx • The nose is the primary airway, (connected to oropharynx as backup airway) • Nasal cavity warms & filters inspired air – Nasal conchae allow air to pass over blood supply to warm it – Vibrissae (nose hair) and mucus trap dust • Important in smell, voice The Airway--Larynx • AKA--voice box • Contains vocal cords, vibrate against each other to produce sound—requires skeletal muscle contraction • Covered by epiglottis during swallowing to separate GI tract from airway. • More prominent in men (Adam’s apple) The Airway--Trachea • • • • AKA—windpipe Below larynx. Splits into two bronchi Has C-shaped rings of cartilage for structure – Otherwise, it would collapse as you inhale. – Rings are open at back to allow for expansion. The Airway--Bronchi • • • • Smaller than trachea Still has rings of cartilage One leads to left lung, the other to the right. Lined with ciliated pseudo-stratified columnar ET – epithelia makes mucus – Cilia move mucus upwards- to be coughed out The Airway--Lungs • Bronchi split into lobar bronchi – Three on the right, two on the left • Lobar bronchi split into bronchioles – Smooth muscle can constrict them • Bronchioles split smaller and smaller alveoli Process of breathing • We use a negative pressure system • To breathe in: lift ribs, lower diaphragm, open airway, and air rushes in to fill the space provided in the lungs. • To breath out: relax. The elasticity of the lungs will push out (enough) air Process of breathing • We use Inspiration a negative pressure system • To breathe in: lift ribs, lower diaphragm, open airway, and air rushes Together: in to fill the space provided in the lungs. Respiration • To breath out: relax. The elasticity of the lungs will push out (enough) air Expiration Pressure • Pressure differences allowing inspiration and expiration are only ~1/150 atm. • Using breathing muscles with the airway closed can change pressure more, forcing blood into and out of the chest The lungs—as organs • One lung on each side, two lobes on the left lung, three on the right • One can be surgically removed (or individual lobes) • In the thoracic cavity—protected by ribs, sternum, spine, shoulder blades • Covered by pleura Pleura • Two layers of pleura—parietal & visceral. • The space between them has fluid for lubrication Pleura • Two layers of pleura—parietal & visceral. Lining chest wall Lining lung surface • The space between them has fluid for lubrication Control of breathing Respiratory center: in brain stem (pons/medulla) Pneumotaxic area controls breathing rate Breathing volume=breathing rate x inflation Control of breathing • Normally: 12 breaths/min. x .5 L /breath=6 L/min. (can increase to 200 L / min. in emergency) Volumes • • • • • • • Tidal volume (TV) about .5 L Inspiratory reserve (IR) about 2.5L Inspiratory capacity (IC) (=TV+IR) Expiratory reserve(ER) about 1.5L Expiratory capacity (EC) (=TV+ER) Vital capacity (VC) (=TV+IR+ER) Residual volume (RV) about 1.5 L Control of breathing CO2 sensors —(pH of blood)higher breathing rate when pH falls – In respiratory center O2 sensors —(not as effective) increase breathing rate & volume when O2 is low – In major arteries Remember how the blood carries gasses? • O2 is bonded to hemoglobin in RBC • CO2 can be bonded to hemoglobin, but is usually dissolved in plasma. Acidity and CO2 • H2O + CO2 H2CO3 (carbonic acid) • pH falls as CO2 dissolves in blood • pH rises as CO2 leaves blood • Low pH makes it easier for RBC’s to give up O2. Branching of the airway • • • • • Trachea Bronchi Lobar bronchi Bronchioles Alveoli Structure of an alveolus Gas exchange • Alveoli are very thin (simple squamous ET) • Filled with inspired air (mixed with unexhaled air already in the lungs) Gas exchange • Capillaries have the thinnest possible ET (simple squamous) • CO2 leaves blood, enters alveolar air • O2 leaves alveolar air, enters blood (By diffusion) Gas exchange in tissues • Cells in the tissues use O2 and make CO2 • Capillaries have the thinnest possible ET (simple squamous) • O2 leaves blood, enters interstitial fluid • CO2 leaves interstitial fluid, enters blood (By diffusion) Respiratory pathology • • • • • • Pneumothorax • Cancer • Emphysema • Punctured lung• Hiccups • Hyper• ventilation • • Cystic fibrosis • Coughing Pneumonia Bronchitis Asthma Pleurisy Cold Influenza Asphyxia • • • • Strep throat COPD Asbestosis Pulmonary Edema • Sinusitis • Anoxia • Nosebleeds