creatinine is a normal waste product produced by muscle metabolism when your kidneys are functioning normally they filter creatinine and other waste products out of your blood and send them out of the body through urine
Tweet. This follows the page describing the basic anatomy of the lower respiratory tract. The term  tracheobronchial tree  or  respiratory tree  refers to the structures of bronchi and bronchioles that terminate with the alveolar ducts, sacs, and, finally, alveoli-that are contained within the lungs.herefore these structures are also referred to as  airways . This pages includes two diagrams of the airways-the main structure of the tracheobroncial tree being shown immediately below, and a second diagram showing the alveoli in further detail further down the page.
1 The other is the trachea, which is the opening air must pass through to get to the lungs. 2  When swallowing occurs, the trachea is covered by a flap called the epiglottis, which prevents food from entering the lungs. 3  The trachea splits into the left and right main stem bronchae. 4  These lead to the left and right lungs. When swallowing occurs, the trachea is covered by a flap called the epiglottis, which prevents food from entering the lungs. 2  The trachea splits into the left and right main stem bronchae. 3  These lead to the left and right lungs. 4  They branch into increasingly smaller tubes as they spread throughout the lungs.