Anatomyof the lungs

The lungs refer to two large organs located in the thorax (ATS,2015). Each lung is made of spongy tissue and positioned on one sideof the chest. The lungs function as the zone of gaseous exchangebetween air and blood. In this regard, they impart oxygen into theblood stream while eliminating carbon dioxide before it reaches toxiclevels (ATS, 2015). Inhaled air enters the lungs via the primary andsecondary trachea. The tubular branches of the bronchi split intosmaller branches called bronchioles (ATS, 2015). Further divisionleads to microscopic structures referred to as alveoli. The exchangeof oxygen and carbon dioxide occurs in the alveoli (ATS, 2015). Theinterstitium forms an intricate network of cells that support thefunction of the microscopic air sacs. The air-filled lungs are linedwith a layer of thin tissue referred to as the pleura (ATS, 2015).The smooth expansion and contraction of the lungs are aided by alayer of lubricating fluid.

Airwayand epithelial anatomy

The airways consist of nasal passages that clean, warm, and moisteninhaled air. Subsequently, the resultant mucus is transmitted to thepharynx. Notably, the tonsils are located in the pharynx. Duringswallowing, the epiglottis blocks the larynx (ATS, 2015). This occursbecause the larynx is stretched up and forward while the tongue ispushed backward (ATS, 2015). The trachea consists of primary andsecondary bronchi that extend into minor branchings. Submucosalglands and smooth muscles line the walls of the trachea (ATS, 2015).Respiratory and terminal bronchioles lack cartilage tissue. Ciliatedepithelium lines the airways. In the epithelium, basal cells causethe regeneration of other cells. Moreover, submucosal glands secretefluid and mucus while goblet cells release mucus (ATS, 2015).

Vascularand lymphatic anatomy

The vascular system comprises a network of vessels that carry lymphand blood in the body. In particular, veins and arteries transportnutrients and oxygen to body tissues while removing wastes fromorgans and tissues (Evans, 2015). Arteries transmit oxygenated bloodto the body while veins transport deoxygenated blood to the heart.Capillaries refer to tiny vessels that branch away from the veins andjoin to form veins (Evans, 2015). The exchange of nutrients, oxygen,and wastes occurs in the capillaries. Furthermore, the vascularsystem forms a significant component of the digestive and respiratorysystems. The lymphatic system comprises of vessels that transportclear liquid known as lymph (Johns Hopkins Medicine). Such a systemexists within the vascular network as it helps to maintain the body’sfluid environment.

Pulmonarynervous system

The pulmonary nerve plexus has several branches that occur along theroots of both lungs (Ross, 2015). Pulmonary circulation consists ofthe transport of deoxygenated blood from the heart to the lungs. Italso includes the subsequent transmission of oxygenated blood fromthe lungs to the heart. Blood from the right atrium and ventricle ispumped to the pulmonary artery and into each lung. After an exchangeof oxygen and wastes occurs at the alveoli, oxygenated blood passesthrough the pulmonary veins back into the heart. Consequently, bloodfrom the left ventricle enters the systemic circulation. Thepulmonary nervous system works to regulate the function of thepulmonary nerves, arteries, and veins (Ross, 2015).

Immunestructure and function

The lungs have an adept immune system that offers protection againstmicrobes that enter the spongy tissue. Inertial forces carry largeparticles out of the airstream and into the pharyngeal wall.Particles in the major airways are collected at the surface bygravity (Parham &amp Janeway, 2015). Subsequently, the particles aremixed with soluble liquids present in the airways. In this manner,the soluble constituents contribute to the lungs` innate immunity.The immune system acts as the primary defense against pathogens suchas viruses, bacteria, foreign cells and tissues (Parham &ampJaneway, 2015).


Evans, J. D. W. (2015). Cardiovascular system (4thed.). Edinburgh, UK: Elsevier.

Johns Hopkins Medicine. Overview of the Vascular Retrieved from,P08254/

Parham, P. &amp Janeway, C. (2015). The immune system. NewYork, NY: Taylor &amp Francis Group.

Ross, J. (2015). Nervous system. St. Louis, Miss.: Mosby.

The American Thoracic Society (ATS). (2015). Anatomy and Function ofthe Normal Lung. Retrieved from