Exam 3 Review:  Chapter 22:  Respiratory Tree

trachea - A thin-walled, cartilaginous tube, anterior to the esophagus, descending from the larynx to the primary bronchi which carries air to the lungs; its wall consists of a pseudostratified columnar ciliated epithelium, a loose fibrous connective tissue submucosa, C-shaped hyaline cartilage rings, and smooth muscle.  nickname - windpipe

trachealis muscle - A thin sheet of smooth muscle running the length of the posterior wall of the trachea, spanning the space between the open ends of the C-shaped cartilage rings which keep the trachea open; its contraction narrows the tracheal diameter (opening) to increase air velocity during a cough or sneeze

carina - The angle made between the two primary bronchi when they diverge at the tracheal bifurcation; it is richly innervated with sensory nerve endings to respond to the arrival of any aspirated material by initiating a cough reflex; it may be visualised as a ridge within the bronchial tree when using a bronchoscope.

tracheotomy - A surgical operation which creates an opening into the trachea with a tube inserted to provide a passage for air; performed when the pharynx is obstructed by edema or cancer or other causes.

endotracheal tube (intubation) - A procedure by which a flexible plastic tube is inserted through the mouth to go down into the trachea; the clinician inserts the tube with the help of a laryngoscope (an instrument which permits one to see down into the trachea, and even see the vocal cords); the purpose of endotracheal intubation is to permit air to pass freely to and from the lungs in order to ventilate the lungs; endotracheal tubes can be connected to ventilator machines to provide artificial positive pressure ventilation.

 
bronchial tree - The bronchi together with all their branches which deliver air to the alveoli of the lungs.

primary bronchi - The thin-walled, cartilaginous tubes, the first branches (right and left) of the trachea, which carry air to the lungs; their walls consist of a pseudostratified columnar ciliated epithelium, a loose fibrous connective tissue submucosa with submucosal glands, O-shaped hyaline cartilage rings, and smooth muscle.

lobar bronchi - The thin-walled, cartilaginous tubes, the first branches of the primary bronchi, which carry air to the individual lobes of the lungs; their walls consist of a pseudostratified columnar ciliated epithelium, a loose fibrous connective tissue submucosa thrown into irregular folds with submucosal glands, O-shaped hyaline cartilage rings, and smooth muscle; as the diameter of the bronchi decreases the size of the cartilage cross-sections also decreases.

segmental bronchi = secondary bronchi - The thin-walled, cartilaginous tubes, the first branches of the lobar bronchi, which carry air to the ~ten bronchopulmonary segments of each lung; their walls consist of a pseudostratified columnar ciliated epithelium, a loose elastic connective tissue submucosa thrown into irregular folds with submucosal glands, O-shaped hyaline cartilage rings, some diffuse lymphatic tissue and smooth muscle; as the diameter of the bronchi decreases the size of the cartilage cross-sections also decreases.

tertiary bronchi - The thin-walled, cartilaginous tubes, the first branches of the the segmental bronchi, which carry air to the lobules of each lung; their walls consist of a pseudostratified columnar ciliated epithelium, a loose elastic connective tissue submucosa thrown into irregular folds with submucosal glands, small O-shaped hyaline cartilage rings, some diffuse lymphatic tissue and smooth muscle; as the diameter of the bronchi decreases the size of the cartilage cross-sections also decreases.

bronchioles - The fine airways which constitute the passages produced by the 11th to 17th divisions of the bronchi within the lung parenchyma; they have luminal diameters from 0.5 mm to 0.2mm; they have no submucosal glands or hyaline cartilage rings within their walls which are lined by a a pseudostratified columnar ciliated epithelium; as the diameter of the bronchioles decrease, the lining epithelium changes to a simple columnar ciliated epithelium and then to a cuboidal ciliated epithelium; they have a prominent outer wall layer of smooth muscle cells capable of constricting the bronchiolar lumen in response to parasympathetic (vagal) inputs; sympathetic fibers dilate the bronchioles.

terminal bronchioles - The final divisions of the bronchioles which are lined by a cuboidal ciliated epithelium and only occasional smooth muscle fibers are observed in their walls; they carry air toward the alveoli.

respiratory bronchioles - The final divisions of the terminal bronchioles which are lined by a cuboidal ciliated epithelium and only occasional smooth muscle fibers are observed in their walls; their walls are interrupted by the presence of occasional alveolar sacs where gas exchange takes place; they divide into the alveolar ducts, which are the smallest branches of the bronchial tree; they carry air toward the alveoli.

ciliated pseudostratified columnar epithelium - The lining membrane of the majority of the branches of the bronchial tree, consisting of a tissue sheet which gives a superficial appearance of being in several layers because the cell nuclei are at different levels, but in which all cells reach the basement membrane, hence it is classed as a simple epithelium; on its apical surface is a brush border of hairlike projections which are the cell organelles known as cilia which are microtubluar motile structures which beat in a oar-like fashion to propel mucus secretions upward through the bronchial tree to the pharynx where they can be swallowed or otherwise expelled.

bronchoscopy  - An examination used for inspection of the interior of the tracheo-bronchial tree, performance of endobronchial diagnostic tests, taking of specimens for biopsy and culture and removal of foreign bodies using a thin, flexible instrument (bronchoscope) which is a flexible plastic tube that can be inserted through the mouth to go down into the airways and which has optical devices and various accessories to perform the actions listed above.

For images from a bronchoscopy, take this link.

For a set of images of the lung made with the Scanning Electron Microscope, take the Lung Tour.

List:

1. In correct sequence the structures of the conducting portion of the respiratory system through which a gas molecule passes during inspiration.

nose/mouth → pharynx → larynx → trachea → primary bronchi → lobar bronchi → segmental bronchi = secondary bronchi → tertiary bronchi → bronchioles → terminal bronchioles → [ respiratory bronchioles* → alveolar sacs* → alveoli*  --  *Note: these last three portions of the airway are not technically a part of the "conducting portion" of the airway because actual respiratory gas exchange occurs in these locations.]

Identify:

1. The type of epithelial tissue lining each part of the conducting portion of the respiratory system and explain why this type of epithelium promotes the functions of its respective part.

2. The structural divisions of the lung supplied by a primary bronchus, lobar bronchus, secondary bronchus, tertiary bronchus, and a terminal bronchiole.