Mechanics of Ventilation (Breathing) PDF SBI3U(G)

THE MECHANICS OF VENTILATION (BREATHING) SBI3U(G) BREATHING CONSISTS OF TWO MOVEMENTS: 1. INHALATION (inspiration) air IN 2. EXHALATION (expiration) air OUT  Lungs Intercostal Action Diaphragm...

THE MECHANICS OF VENTILATION (BREATHING) SBI3U(G) BREATHING CONSISTS OF TWO MOVEMENTS: 1. INHALATION (inspiration) air IN 2. EXHALATION (expiration) air OUT  Lungs Intercostal Action Diaphragm Air movement Muscles (IM) volume pressure External IM contracts Inhale contract (pull ribs Air in (flattens) up and out) External IM relaxes Exhale relaxes (ribs Air out (rises) down)  RELAXES CONTRACTS CONTRACTS ◼ During strenuous exercise, internal intercostal muscles will contract to pull the ribcage down to force air out of lungs more quickly. Measuring Lung Volumes To measure different lung volumes, we use a spirometer (a machine that measures the volume of air inhaled/exhaled). A spirograph is the diagram that shows the volumes of air a person moves depending on their breathing movements (breathing normally, deep breathing in and out, etc) The resulting graph is called a spirograph. Lung Volumes and Capacities Spirometer Graph S6keEWgG CAPACITY Total lung capacity (TLC) = the maximum volume of air that can be held in your lungs during a single breath (the sum of your vital capacity and your residual volume). **Your textbook describes it inaccurately) LUNG CAPACITY Tidal volume (TV) = the volume of air inhaled or exhaled during a normal, involuntary breath (approx. 0.5 L) LUNG CAPACITY Inspiratory reserve volume (IRV) = the volume of air that can be forcibly inhaled after a normal inhalation LUNG CAPACITY Expiratory reserve volume (ERV) = the volume of air that can be forcibly exhaled after a normal exhalation LUNG CAPACITY Vital capacity (VC) = the maximum amount of air that can be inhaled or exhaled LUNG CAPACITY Residual Volume (RV) = is the volume of air remaining in the lungs after maximum forceful expiration. LUNG VOLUMES & CAPACITIES ◼ Total lung capacity (TLC) ◼ average about 4 - 6 L of air ◼ only a small amount of this capacity is used during normal respiration ◼ TLC depends on the person's: a) age (lungs lose their elasticity with age) b) body size c) chest size d) Anatomical sex (females about 20-25% lower TLC than males) e) general fitness (athletic, sedentary) f) choices/disorders (smoker, emphysema, asthma, cystic fibrosis) A collapsed lung occurs when air enters the pleural space, the area between the chest wall and the lung. Air in the pleural space can build up and press against the lung, causing it to collapse partially or fully. Also called a deflated lung or pneumothorax, a collapsed lung needs immediate medical care. HOMEWORK ◼ P 446#5,8