Anatomy &amp; <a href="/keyword/physiology-ii/" >physiology ii</a> Notes 3/29/07 <a href="/keyword/respiratory-system/" >respiratory system</a> Need oxygen because it is the last electron acceptor (needed to make ATP) Path of air: inhale through nose or mouth pharynx trachea trachea branches into two bronchi (one to each lung) bronchi branch into bronchioles bronchioles open into air sacs called alveoli o Lungs are essentially the alveoli and blood vessels not dense (mostly air) o Inhaling through nose is advantageous, especially if it is cold because the hair has an opportunity to warm up, nose hairs also filter any particles from the air Epiglottis cartilaginous structure that prevents anything besides air from entering the trachea, acts like a lid and closes when we swallow and forces food and fluid into the esophagus o Heimlich maneuver Vocal cords vibrate to make sound Trachea cartilaginous structure, stiffer than the esophagus Ciliated cells produced mucus, cilia is involved in getting particles out of the <a href="/keyword/respiratory-system/" >respiratory system</a> o Cilia are very sensitive stop functioning where they're exposed to certain chemicals (in cigarette smoke, pollution, etc.) Macrophages ready to phagocytize microorganisms or particulate matter in the <a href="/keyword/respiratory-system/" >respiratory system</a> o Also affected by cigarette smoking and pollutants ~70% of cancers are attributed to smoking Alveolus is only one cell-layer thick diffusion distance for oxygen and carbon monoxide is very short o Type II cells secrete surfactant Surfactant coats the inside of the alveoli, prevents collapse of alveoli, phospholipid-like Difference in pressure air movement o Inhalation contraction of intercostal muscles and diaphragm (comes down and increases space), thoracic cavity enlarges, parietal pleura gets pulled, interpleura space pressure gets lower and acts as a vacuum to pull lungs open and pressure goes from 760 to 758 mm Hg o D Respiratory muscles intercostal muscles and diaphragm Diaphragm dome-shaped when relaxed Pleura parietal (on outside, attached to thoracic wall), visceral (against lungs)