Functional anatomy of the respiratory tract

Atmospheric oxygen is an indispensable element required in order for mammalian cells to function normally. The mammalian respiratory system, through pulmonary ventilation and gas diffusion, provides the physical mechanisms by which oxygen gains access to all body cells and through which carbon dioxide is eliminated from the body. The network of tissues and organs of the respiratory system helps the mammalian body cells to absorb oxygen from the air to enable the tissues and organs to function optimally. The advent of the coronavirus disease 2019 (Covid-19) Pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has stimulated heightened and refocused interest in the study of various aspects of the respiratory system. The SARS-CoV-2 targets the respiratory system mucosal cells and in a cascade of biological processes curtails the ability of the respiratory system to absorb and deliver oxygen to the pulmonary blood and body cells often resulting in severe disease and/or death. The mucosa and submucosa of the respiratory tract are adapted to provide both innate and adaptive immune defense mechanisms against pathogens including the SARS-CoV-2. The entire respiratory tract is covered by a mucosa that transitions in its structural and functional characteristics from the upper respiratory tract to the lower respiratory tract. This chapter provides an overview of the functional anatomy and immunology of the respiratory tract covering the mucosa from the upper respiratory tract all the way up to the alveolar epithelium. In the advent of the covid-19 pandemic, a broader perspective and understanding of the anatomy and immunology of the respiratory tract will enable general readers and researchers to fully appreciate the discourse in covid-19 research as it affects the respiratory tract.

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New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099544 ◽

1981 ◽

Vol 39 ◽

pp. 624-625

Author(s):

J.L. Carson ◽

A.M. Collier

Keyword(s):

Respiratory Tract ◽

Airway Epithelium ◽

Defense Mechanisms ◽

Normal Growth ◽

Fetal Lung ◽

Secretory Cells ◽

Airway Epithelial ◽

Ciliated Cells ◽

Conducting Airway ◽

Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

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Functional Anatomy Underlying Pharyngeal Swallowing Mechanics and Swallowing Performance Goals

Perspectives of the ASHA Special Interest Groups ◽

10.1044/2019_pers-sig13-2018-0014 ◽

2019 ◽

Vol 4 (4) ◽

pp. 648-655

Author(s):

William G. Pearson ◽

Jacline V. Griffeth ◽

Alexis M. Ennis

Keyword(s):

Functional Anatomy ◽

Neuromuscular Control ◽

Upper Esophageal Sphincter ◽

Performance Goals ◽

Laryngeal Elevation ◽

Port Closure ◽

Swallowing Dysfunction ◽

Hyoid Movement ◽

Pharyngeal Swallowing ◽

Pharyngeal Constriction

Purpose Rehabilitation of pharyngeal swallowing dysfunction requires a thorough understanding of the functional anatomy underlying the performance goals of pharyngeal swallowing. These goals include the safe and efficient transfer of a bolus through the hypopharynx into the esophagus. Penetration or aspiration of a bolus threatens swallowing safety. Bolus residue indicates swallowing inefficiency. Several primary mechanics, or elements of the swallowing mechanism, underlie these performance goals, with some elements contributing to both goals. These primary mechanics include velopharyngeal port closure, hyoid movement, laryngeal elevation, pharyngeal shortening, tongue base retraction, and pharyngeal constriction. Each element of the swallowing mechanism is under neuromuscular control and is therefore, in principle, a potential target for rehabilitation. Secondary mechanics of pharyngeal swallowing, those movements dependent on primary mechanics, include opening the upper esophageal sphincter and epiglottic inversion. Conclusion Understanding the functional anatomy of pharyngeal swallowing underlying swallowing performance goals will facilitate anatomically informed critical thinking in the rehabilitation of pharyngeal swallowing dysfunction.

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