Introduction
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
The mucosa of the esophagus consists of nonkeratinized stratified squamous epithelium, lamina propria (areolar connective tissue), and a muscularis muscosae (smooth muscle). Near the stomach, the mucosa of the esophagus also contains mucous glands. The stratified squamous epithelium associated with the lips, mouth, tongue, oropharynx, laryngopharynx, and esophagus affords considerable protection against abrasion and wear-and-tear from food particles that are chewed, mixed with secretions, and swallowed. The submucosa contains areolar connective tissue, blood vessels, and mucous glands. The muscularis of the superior third of the esophagus is skeletal muscle; the intermediate third is skeletal and smooth muscle. and the inferior third is smooth muscle. The superficial layer is known as the adventitia, rather than the serosa, because the areolar connective tissue of this layer is not covered by mesothelium and because the connective tissue merges with the connective tissue of surrounding structures of the mediastinum, through which it passes. The adventitia attaches the esophagus to surrounding structures.
Physiology of the Airways
Anthony J. Hickey, Sandro R.P. da Rocha in Pharmaceutical Inhalation Aerosol Technology, 2019
Located in the submucosa of cartilage-containing airways and in the lamina propria of the trachea are glands that secrete mucus into the airway lumen (Reid, 1960). Each mucous gland consists of four regions: the ciliated duct, collecting duct, mucous tubules, and secretory tubules (Meyrick et al., 1960). The ciliated duct opens to the lumen of the airways and is lined by ciliated epithelial cells. It merges with the collecting duct, the walls of which comprise columnar cells. Mucous cells line the mucous tubules that lead from the collecting duct. Serous cells (which contribute to the more liquid component of mucus) line the blind-ended serous tubules that are located at the distal ends of the mucous tubules. Several secretory tubules feed into the collecting duct. Mucus is secreted via the collecting and ciliated ducts into the lumen of the airways. Goblet cells, located in the epithelium of the larger central airways, secrete mucus directly into the airway lumen (Rogers, 1994). Mucus hypersecretion results from an increase in the number and/or size of mucous glands and goblet cells in disease states, such as chronic bronchitis (Finkbeiner, 1999; Rogers, 1994).
Relationship Between Airway Wall Thickness and Airway Hyperresponsiveness
Alastair G. Stewart in AIRWAY WALL REMODELLING in ASTHMA, 2020
The studies of airway wall components showed a consistent increase in the area of smooth muscle area ranging from 50 to 230% of control values in cases of fatal asthma and from 25 to 150% in cases of nonfatal asthma. The changes were most marked in central airways in cases of fatal asthma and in the large membranous bronchioles in cases of nonfatal asthma. The differences between the nonfatal and fatal cases with regard to smooth muscle were greatest in the cartilaginous airways. The area of mucous gland was increased in asthma, particularly in the fatal cases. In cases of asthma, epithelial damage was variable and subject to artefact due to post-mortem change or biopsy trauma; however, the area of the epithelium was increased. The data regarding the area of cartilage in cases of asthma are less consistent than for other airway wall structures.
Salamanders and caecilians, neglected from the chemical point of view
Published in Toxin Reviews, 2022
Isadora Alves de Vasconcelos, Jéssica Oliveira de Souza, Jessica Schneider de Castro, Carlos José Correia de Santana, Ana Carolina Martins Magalhães, Mariana de Souza Castro, Osmindo Rodrigues Pires Júnior
The amphibian skin is of extreme importance. Being permeable to water, it has several key roles necessary for the survival of these animals, such as gas exchange, osmoregulation, control of temperature, and defence mechanisms against pathogens and predators (Duellman et al.1994, Clarke 1997). All amphibians have mucous glands and poison glands on their skin that also help with these functions. Mucous glands are small and numerous, usually scattered throughout the body, keeping the skin moist and providing conditions for cutaneous breathing. The poison (= granular) can be found accumulated in specific spots or evenly distributed, depending on the species. They are associated with directly innervated myoepithelial cells, suggesting the release of their products in situations of stress or mechanical compression created by predators (Duellman et al.1994, Toledo and Jared 1995, Clarke 1997).
Nasal mucus proteome and its involvement in allergic rhinitis
Published in Expert Review of Proteomics, 2020
Peter Valentin Tomazic, Barbara Darnhofer, Ruth Birner-Gruenberger
Nasal mucus consists of a variety of lipids, glycoconjugates, cells, cellular debris, and proteins. Nasal mucus proteins work as enzymes or enzyme inhibitors, antioxidants, antibacterial agents, and mediators. Well described and abundant proteins in nasal mucus are mainly antimicrobial proteins like lysozyme and lactotransferrin as well as secretory immunoglobulins IgA, IgE, IgG, and albumin. Other proteins include kallikrein, antiproteases, ß-glucuronidase, and α-galactosidase as described in early, mainly ELISA-based, studies [4,5]. Mucus proteins stem from epithelial cells, goblet cells of sero-mucous glands in the submucosal tissue, either by secretion or cell death. Cellular debris in the mucus can be detected by its DNA or nucleic products such as histones [3]. Another important contributor to the protein composition of the mucus is proteins exudated from plasma, which is regarded as a key defense mechanism [3,4,6,7]. Especially in pathological conditions like allergic rhinitis, lysozyme, and lactotransferrin were shown to be up-regulated after provocation with allergen [4]. These early studies already underlined the importance of the nasal mucus proteome in disease, but were restricted to selected distinct proteins or small groups of proteins.
Novel role for integrin β4 in asthmatic children infected with Mycoplasma pneumoniae
Published in Journal of Asthma, 2023
Xia Ou, Zhongyue Fang, Weijie Li, Yunxin Xia, Jianming Xia, Jihong Zhang
Asthma respiratory diseases are characterized by various degrees of airflow obstruction associated with chronic inflammatory tissue remodeling, which subsequently results in increased contractility of the surrounding smooth muscles. These features, among other factors, lead to bouts of airway narrowing and the classic symptoms of wheezing. Airway narrowing is typically reversible with or without treatment (5,6). Occasionally, the airways change. Typical changes of chronic inflammatory tissue remodeling include an increasing number of eosinophils and thickening of the lamina reticularis. Over time, airway smooth muscles may increase in size with an increase in the number of mucous glands. Other cell types involved in asthma include T lymphocytes, macrophages, and neutrophils (6,7). There may also be involvement of other components of the immune system, including cytokines, chemokines, histamine, and leukotrienes. Goblet cell hyperplasia and mucus hypersecretion in the airway epithelium are hallmarks of chronic inflammatory lung diseases, including chronic obstructive pulmonary disease (COPD) and asthma (8).
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