First Responder EMS Curriculum for Training Centers in Eurasia

that the pharynx performs the dual function as a passageway for both air and food/water.This makes it a site for possible airway obstruction. The tongue is not part of therespiratory system, but may obstruct the airway as well. At the lower portion of thepharynx lies the epiglottis, a leaf-shaped structure that prevents food and water fromentering the trachea during swallowing. Below the epiglottis is the entrance to thetrachea (windpipe). This entrance houses the vocal cords within the cartilaginous larynx(voicebox). The trachea then divides into smaller and smaller airways (bronchi,bronchioles) before reaching the lungs. The lungs are the site of oxygen and carbondioxide exchange. The diaphragm is a muscle that separates the thorax from theabdomen. Its primary function, along with the intercostal muscles of the chest wall, is toventilate the lungs. Ventilation is the process of moving air into and out of the lungs.The physiology, or function, of the respiratory system is to bring oxygen-rich air intothe lungs, exchange oxygen for carbon dioxide, and remove the carbon dioxide–rich airfrom the lungs. The diaphragm moves down, the chest wall expands, thus drawing airinto the lungs (inhalation). Oxygen and carbon dioxide are exchanged in the lungs. Thediaphragm then moves up, the chest wall moves inward, and air is moved out of thelungs (exhalation).Special consideration is given to the respiratory system in infants and children, becausethe airway is much more easily obstructed in this group of individuals. All of thestructures of the respiratory system are smaller in this group, compared with adults. Thetongue of infants and children is proportionately larger. The trachea is of smallerdiameter and more flexible, allowing this area to collapse or become obstructed morereadily. Always remember that the primary cause of cardiac arrest in infants andchildren is an uncorrected respiratory problem.c. Circulatory SystemThe circulatory system functions to deliver oxygen and other nutrients to the tissues ofthe body, as well as remove waste products from these tissues.The anatomy of the circulatory system is composed of the heart and blood vessels. Theheart functions as the pump of the body’s blood supply. The heart is composed of fourchambers: two upper atria and two lower ventricles. The right atrium receives oxygenpoorblood returning from the veins of the body. The right ventricle then pumps thisblood into the lungs to replenish it with oxygen and remove carbon dioxide. Theoxygen-rich blood is then returned into the left atrium, which pumps the blood into theleft ventricle. The left ventricle pumps this oxygen-rich blood to the entire body. Valvesare located in between the atria and ventricles to prevent back flow of blood. Valves arealso located at the exits of the ventricles into the blood vessels.The blood vessels consist of the arteries, veins, and capillaries. They carry bloodthroughout the entire body. The arteries are muscular tubes that carry oxygen andnutrient-rich blood away from the heart to the rest of the body. The heart is alsosupplied by its own special arteries called the coronary arteries. Anatomically, severalarteries are very important, because their pulsations can be palpated at the skin surface.Familiarity with these arteries is vital for circulatory assessment. Four major arteries canbe readily palpated. The carotid arteries supply the brain and can be palpated on eitherside of the neck, just lateral to the trachea (windpipe). The femoral arteries supply thelower extremities and can be palpated in the groin area (groove between the abdomenFirst Responder EMS Curriculum/AIHA, July 2002 33