Reading of Chest Radiographs Some basic Anatomy and Physiology; including Pleural Fissures, Mediastinal Lines, The Bronchi and Para-Tracheal Lines, Hilar Anatomy, the Pulmonary Lobules, Acini and Lung Cortex, Distribution of Lung Disease in Relation to Anatomy and Physiology, Basic CT and Pathological Anatomy.
Fred W Wright in Radiology of the Chest and Related Conditions, 2022
Within each lobe and segment; the airways divide by asymmetric dichotomy (i.e. usually into two at each division, but often into unequal parts. Cartilage is continued in the bronchial walls, but stops in the bronchioles. The smaller bronchi divide at almost 1 cm intervals until the terminal bronchioles are reached, when branching occurs at 1 - 2 mm intervals, i. e. with branches passing into the secondary lobules, which are partially separated from one another by the inter-lobular septa - these secondary lobules appear to be the most important radiological sub-units of the lung. Within the secondary lobules, each terminal bronchiole gives rise to between two and seven respiratory bronchioles which take part in gas exchange and also give rise to the alveolar ducts and alveoli. The primary lobules are much smaller, and consist of a group of alveoli arising from a respiratory bronchiole, via an alveolar duct. An acinus is produced by the branchings of a terminal bronchiole, and may be seen on bronchograms as a 'rosette' if 'bronchiolar filling' occurs. Disease processes may give rise to similar 'alveolar patterns', especially the 'acino-nodose' (or 'tree in bud') pattern seen in some cases of tuberculosis.
Molecular Pathophysiology and the Clinical Presentation of COVID-19
Srijan Goswami, Chiranjeeb Dey in COVID-19 and SARS-CoV-2, 2022
The trachea separates into two primary (main) bronchi called right and left bronchi. Inside the lungs, each primary bronchus separates into secondary bronchi which are further subdivided into tertiary bronchi. These tertiary bronchi form bronchioles. Bronchioles having a diameter of 1 mm or less are known as terminal bronchioles. The trachea and bronchi are together called the tracheobronchial tree. The structural and functional unit of lungs, known as the respiratory unit, consists of respiratory bronchioles, alveolar ducts, alveolar sacs, antrum, and alveoli, and is responsible for the actual exchange of gases between lungs and blood. Each alveolus is lined by epithelial cells called alveolar cells or pneumocytes. Pneumocytes are of two types (Hall, 2015; Ralston et al., 2018):Type I alveolar cells. Type I alveolar cells are the squamous epithelial cells forming about 95% of the total number of cells. These cells form the site of gaseous exchange between the alveolus and blood (Hall, 2015; Ralston et al., 2018).Type II alveolar cells. Type II alveolar cells are cuboidal in nature and form about 5% of alveolar cells. These cells are also called granular pneumocytes. Alveolar fluid and surfactant are secreted by these cells (Hall, 2015; Ralston et al., 2018) (Figure 3.5).
Ageing
Henry J. Woodford in Essential Geriatrics, 2022
In older adults, there is a reduction in lung elastic recoil (making them stretchier) but also a reduction in chest wall compliance (making expansion less easy). Associated with frailty, muscles of respiration (including the diaphragm) become less strong. The combined effect of these changes is that total lung capacity (TLC) remains constant, but the reduced elastic recoil results in an increase in residual volume (RV). Vital capacity (VC) can be calculated by subtracting RV from TLC. Therefore, VC becomes reduced (seeFigure 1.4). Forced expiratory volume in one second (FEV1) is lower in older adults. As is diffusing capacity. Loss of terminal bronchioles contributes to age-related decline in pulmonary function.58 Partial pressure of oxygen (pO2) is reduced but that of carbon dioxide (pCO2) is unchanged. Respiratory drive in response to hypoxia or hypercapnia is impaired.
Adverse pulmonary effects after oral exposure to copper, manganese and mercury, alone and in mixtures, in a Spraque-Dawley rat model
Published in Ultrastructural Pathology, 2023
M Draper, Mj Bester, M Van Rooy, Hm Oberholzer
The general histology of pulmonary tissue was evaluated with H&E and representative images, at X40 magnification, are shown in Figure 1 and Figure 2. In Figure 1A, the alveolar tissue of the control (saline) group has a well-defined alveolar space (A), thin epithelial walls, fine interstitium, type I (P1) and II (P2) pneumocytes and capillaries (c) containing erythrocytes (Er). The alveolar tissues of the experimental groups are presented in Figure 1(B–H). The histological architecture of the pulmonary tissue shows thickened inter-alveolar septa (red arrows) and altered intra-alveolar (green arrows) spaces in all the experimental groups (B to H). In Figure 2A, the bronchiole structure of the control (saline) group is depicted and has an intact epithelial lining (E) and smooth muscle (SM) surrounding the bronchiole. The bronchiole tissue of the experimental groups are presented in Figure 2(B–H). Histological architecture of the bronchioles shows stratification of epithelium (SE), disrupted smooth muscle (black ring) and desquamation of the epithelia (asterisk) to varying degrees in all the experimental groups (B to H). Stratification of epithelia occurs due to the metaplasia of normal pseudostratified pulmonary epithelia to an abnormal stratified form.34,35 The desquamation is evident by the presence of cellular debris within the bronchioles.
Liposomal drug delivery to the lungs: a post covid-19 scenario
Published in Journal of Liposome Research, 2023
S. Swathi Krishna, M. S. Sudheesh, Vidya Viswanad
For e.g. The fungi Aspergillus is located in the lungs’ terminal bronchioles and terminal airways (Carpagnano et al. 2014). The virus herpes simplex virus is located in the oropharynx region (Robinson 2004). Inhaled antibiotics are used for treating bacterial biofilm infection (Boisvert et al. 2016, Lin et al. 2020, Sharma et al. 2021). It reduces the systemic adverse effect and delivers a highly concentrated dose at the respiratory site (Lin et al. 2020). Another group of anti-infective, anti-fungal agents, itraconazole, through inhalation, is effective against Aspergillus. This inhaled drug can reduce the systemic toxicity of the drugs and is a better alternative (Vieira et al. 2016). Also, the anti-viral Zanamivir, formulated as an inhalational powder, is effective against influenza. It is formulated under the brand name Relenza (Cai et al. 2016). Some examples of anti-infective agents used through the inhalational route are given in Table 3 below.
Nanocrystals based pulmonary inhalation delivery system: advance and challenge
Published in Drug Delivery, 2022
Pengfei Yue, Weicheng Zhou, Guiting Huang, Fangfang Lei, Yingchong Chen, Zhilin Ma, Liru Chen, Ming Yang
The lungs are the organs that contact with the exchange of air between the organism and the outside world. They are divided into two main regions: the conducting airway region and the respiratory region. The airway is a continuous branch from the bronchi to the lungs and consists mainly of bronchi, bronchioles, and terminal bronchioles. As the bronchi continue to branch, the diameter of the tubes becomes smaller, the tube wall becomes thinner, and the structure of the tube wall changes gradually. The annular smooth muscles of the bronchi contract or relax under splanchnic nerves innervation and it is responsible for the regulation of airflow passage into the alveoli. This is the site where the lung tissue completes gas exchange consisting of respiratory bronchioles, alveolar ducts, lung sacs, and alveoli. The respiratory bronchiole is the transitional pipes between the pulmonary airway and the respiratory site. Each respiratory bronchiole branch is divided into 2–3 alveolar ducts. The alveolar sacs are the common opening of several alveoli and are connected to the alveolar ducts. The gut is the main site for the digestion and absorption of nutrients.
Related Knowledge Centers
- Bronchus
- Epithelium
- Gas Exchange
- Respiratory Tract
- Smooth Muscle
- Submucosa
- Lung
- Cilium
- Respiratory System
- Pulmonary Alveolus