Anatomy of the Lungs

In man the lungs lie in the pleural portion of the thoracic cavity (Fig. 1) and extend from the diaphragm (base of the lungs) to a point slightly above 

Copyright 1987 by Academic Press, Inc. All rigltts of reproduction in any form reserved. 

The trachea passes from the larynx to the level of the fourth thoracic vertebra, where it divides into the two main bronchi that enter the right and left lungs. The anterior and lateral walls of the trachea and main bronchi are composed of about 20 C-shaped plates of cartilage, which are joined together by a posterior wall composed of bundles of interlacing smooth-muscle fibers, epithelial cells, mucus glands, and elastic fibers. A schematic diagram of the trachea and main bronchi is presented in Fig. 2. Just after the tracheal 

At the terminal point of the airways, the terminal bronchiole becomes the acinus, or the respiratory unit, of the lung. The acini vary in size but in general contain several generations of respiratory bronchioles (bronchioles that have alveolar sacs directly opening to their lumen), which lead to alveolar ducts and ultimately alveolar sacs. Connective tissue lines the airways and forms septa that separate acinus from acinus. Collateral ventilation can occur, however, between acini through the pores (the pores of Kohn) that are located in the adjacent alveolar walls. 

Smoolli Muscle Bosemeni Membront Epiihetiai Cell  

---

Fig. 1 The anatomy of the lungs showing the major airway subdivisions.

The underpressure created in the respiratory tract is the driving force for the airflow through an inhalation device. The attainable underpressure and the rate of the airflow both depend on the total resistance in the airways and inhaler. The pressure drop achieved during inhalation is furthermore a function of the anatomy of the lungs, the effort made by the patient, pathological factors and the presence of exacerbations (e.g. in case of asthma). 

Fig. 3.1 Schematic diagram of the human respiratory system. The gross anatomy of the lung, the covering membranes (pleura), airways and air sacs (alveoli) are shown. The average diameter of portions of the air flow system are indicated trachea, 20 mm bronchus, 8 mm terminal and respiratory bronchioles, 0.5 mnn alveolar duct, 0.2 mm alveolar sacs, 0.3 mm.

We outlined the gross and cellular anatomy of the lung as background for summarizing the mechanisms of disease induction associated with exposure to fibrous materials. Such an exercise is a bit premature, as even the normal biologic processes of fibrosis and cell differentiation or action are not fully understood (Gee and Lwebuga-Mukasa, 1984). We can briefly outline some of the experimental approaches that are yielding information at this time. It should be reiterated that the experimental approach received a tremendous impetus when UICC samples were made available in 1965. 

Typically, uranium is present in limited eoneentrations in the air, and uranium partiele inhalation is minimal (ATSDR, 1999 Harley et al, 1999). Uranium particle deposition in the respiratory traet is governed by the physical forces that effeet partiele behavior in the air, as well as the anatomy of the respiratory traet (ATSDR, 1999 Bleise et al, 2003 Phalen and Oldham, 2006). The anatomy of the lungs is important as this affects the clearance mechanisms available to deal with deposited particles, and the degree of actual uranium absorption that will occur. In addition to the aerodynamic diameter (AD) of the particle, the solubility of the inhaled uranium is an important determinant as to how much uranium will be absorbed (Eidson, 1994 Lang et al, 1994). 

Tyler WS, Julian MD. Gross and subgross anatomy of the lungs, pleura, connective tissue septa, distal airways, and structural units. In Comparative Biology of the Normal Lung, Parent RA, ed. CRC Press Boca Raton, FL, 1991, pp. 37-48. 

Basic Facts about Asthma. Patient s knowledge is improved. The anatomy of the lungs and bronchi and the manner in which inflammation can lead to airway hyperreactivity and bronchoconstriction should be explained in easy-to-understand terms. The link between allergic inflammation and bronchoconstriction should be clarified. Patients may be instructed to use two basic types of medications bronchodilatory (relievers) and anti-inflammatory (controllers) medications. Charts and airway models can clarify the programme. 

Mason, RobertJ., Jay A. Nadel, and John F. Murray. Murray and Nadel s Textbook of Respiratory Medicine. 5th ed. Philadelphia Elsevier Saunders, 2010. The quintessential textbook on pulmonary medicine. Includes chapters on every aspect of pulmonary disease management from basic anatomy of the lungs to lung transplantation. 

The complex functions of the lung and pulmonary system are accomplished through a series of specialized cells (more than forty types have been identified), tissues, and structures. Standard medical texts such as Gray s Anatomy (Warwick and Williams, 1973) and Functional Anatomy erf the Lung (Nagaishi, 1972) should be consulted for details, but for our purposes, we describe four features that ensure optimum lung function, before discussing the diseases that affect the system. 

For more detailed information on the respiratory tract, the pleura, and the lymphatic system, consult Gray s Anatomy or other standard medical texts. A comprehensive review of the lung and its structure and function is presented in Nagaishi (1972). 

Nagaishi, C. (1972). Functional Anatomy and Histology of the Lung. University Park Press, Baltimore, MD, Igaku-Shoin, Ltd., Japan. 

Factors that also govern the therapeutic effect are the anatomy and physiology of the individual and diseases of the lung. These are uncontrollable variables that are important to be aware of. The lung divides dichotomously over 23 generations until it reaches the alveolar sacs. There are 300 million of these covering more than 140 m2. The conducting airways are covered with smooth muscle and are... 

Gaseous pesticides are evenly dispersed in the air. In the case of inhalation, the anatomy and physiology of the respiratory system diminishes the pesticide concentration in inspired air. As pesticides are mostly lipid-soluble, they are usually not removed in the upper airways but tend to deposit in the distal portion of the lung, the alveoli [83] and may then be absorbed into the blood stream. 

FIGURE 11.2 Anatomy of the human respiratory tract. Deposition of nerve agent vapor or aerosols in the different regions of the lung can lead to different symptomology. Upper airway deposition can lead to immediate respiratory distress. Alveolar deposition leads to systemic distribution of the nerve agent. 

Taylor AE, Rehder K, Hyatt RE, Parker JC. Anatomy and function of the lung. In Taylor AE, Rehder K, Hyatt RE, Parker JC, eds. Clinical Respiratory Physiology. Philadelphia Saunders, 1989 3-24. 

Hogg JC, Williams J, Richardson JB, Macklem PT, Thurlbeck WM. Age as a factor in the distribution of lower airway conductance and in the pathological anatomy of obstructive lung disease. N Engl J Med 1970 282 1283-1287. 

Anatomy perceived as a dynamic science, both in its functional orientation and experimental approach, has molded the author into a multifaceted scientist. In the present work, the author successfully combines morphology, biochemistry, and physiology, providing the basis for a comprehensive understanding of the normal and abnormal structure and function of the lung. 

Once again, it is important for the operator to be completely familiar with normal anatomy and superficial anatomic landmarks. The traditional subclavian puncture is carried out in the middle third of the clavicle. This location is frequently associated with an increased risk of vascular trauma, pneumothorax, and a lack of success. An alternate approach calls for the puncture at the apex of an angle formed by the clavicle and first rib (Fig. 4.11) (57). This location is remote from the apex of the lung, and the venous structure is generally much larger. 

---