The Lungs Anatomy, Pictures Health Conditions and More
Lungs are vital for respiration by bringing inspired air into close contact with venous blood in the pulmonary capillaries, they oxygenate the blood.
The lungs of cadavers may have shrunk, become firm or hard, and be discolored, but in healthy people, they are light, soft, and spongy and occupy the entire pulmonary cavity.
Additionally, they are elastic and shrink back to approximately one-third of their original size when the thoracic cavity is opened. Mediastinum separates them from one another.
We will examine in this article, including the anatomical relationships, neurovascular supply, and clinical correlations.
Functions:
| Gaseous Exchange | Oxygen is necessary for every cell in your body to survive. Oxygen and other gases are found in the air we breathe. Oxygen is transported into the bloodstream through the lungs that are then carried through RBCs to the entire body. A waste gas called carbon dioxide is exchanged between each cell in our body. Afterwards, our bloodstream transports these waste gases back to our lungs, where they are exhaled. Gas exchange is a process carried out automatically by our lungs and respiratory system. |
| Moisturization and humidification | The air must be brought to the proper body temperature and properly moisturized, and this function is performed by our lungs. |
| Protection | Our lungs play an important role in protecting our bodies from harmful substances. Coughing, sneezing, filtering, and swallowing are ways to achieve this. |
| Acid-base balance | By releasing carbon dioxide, the lungs control your body's pH balance. The compound carbon dioxide has a slightly acidic pH. It is also a waste product generated by cells in the body as they use oxygen. The kidneys assist the lungs in maintaining an acid-base balance by excreting acids or bases. |
Anatomy of the lungs:
Each has:
| Apex | A blunt end of the lung that ascends above the level of the 1st rib into the root of the neck. The apex of the lung is covered by the cervical pleura. |
| Base | This is the inferior concave drain surface of the lung, opposite the apex, which rests on and accommodates the diaphragm on the opposite side. |
| Lobes | Three in the right lung Two in the left lung |
| Surfaces (Three) | CostalMediastinaldiaphragmatic |
| Borders | AnteriorInferiorposterior |
The surface of the lungs:
Three lung surfaces correspond to three different areas of the thorax.
- The mediastinal surface: the lateral aspect of the middle mediastinum is the mediastinal surface . This surface is home to hilum (where structures enter and leave, also known as the root of the lungs).
- Diaphragmatic surface: This surface is formed where the base of the lung is. Located at the top of the diaphragm, this part is concave in shape. Concavities in the right lung are more prominent because the right dome is higher because of the presence of the liver underneath.
- The coastal surface: Thia surface is smooth and convex. This surface gets its name because it faces the internal surface of the chest wall. In the chest, it is separated from the ribs and innermost intercostal muscles by the costal pleura.
Borders:
- The anterior border: This border of is formed as a result of the convergence of the costal and mediastinal surfaces. A deep notch marks the anterior border of the left lung, created by the apex of the heart. This notch is known as the cardiac notch.
- The inferior border: This border is mainly responsible for the separation of the base from the costal and mediastinal surfaces.
- The posterior border: Anatomically, this border is smooth and rounded (in contrast to the other two borders, both of which are sharp). This border is formed when the costal and mediastinal surfaces meet posteriorly.
Lobes and fissures:
The Left and right lung/lungs are not identical in their lobular structure.
There are three lobes in the right human/lung: superior, middle, and inferior. These lobes are formed when two fissures divide the human/lung
- Oblique fissure: This fissure extends from the inferior border to the posterior border.
- Horizontal fissure: The horizontal fissure runs horizontally from the sternum to the level of the fourth rib, where it terminates by meeting with oblique fissure.
A similar oblique fissure separates the left lung's superior and inferior lobes.
Bronchopulmonary segments:
They are functionally divided into bronchopulmonary segments. In a lobe, the bronchopulmonary segments are the largest subdivisions. Their connective tissue septa separate them from adjacent segments, allowing them to be surgically resectable. In the right lung, there are ten bronchopulmonary segments, while the left has eight.
The bronchial tree:
The bronchi divide further to produce bronchioles less than 1mm in diameter. Each bronchiole is divided into 50 to 80 terminal bronchioles, the final branches of the respiratory bronchioles. As a functional unit, the acinus of the human/lung includes respiratory bronchioles, alveolar ducts, and sacs, and the alveolar. The trachea and terminal bronchioles undergo approximately 16 generations of branching. When the pulmonary airways become smaller, the walls of the lungs change structurally.
Pleura:
Each lung is lined by a double membranous layer known as the pleura. some of the important features of pleura are as follow:
| Pulmonary pleura or visceral pleura | This layer of pleura lines the lung |
| parietal pleura The parietal pleura consist of four parts: coastal pleura mediastinal pleura diaphragmatic pleura cervical pleura | This layer of pleura lines the pulmonary charities and is attached to the thoracic wall, mediastinum, and diaphragm. This part of the pleura lines the internal surface of the thoracic wallThis part of the pleura lines the lateral aspect of the mediastinumThis part lines the superior surface of the diaphragm on both sides of the mediastinum extends into the neck through the superior thoracic aperture, forming a cup-shaped dome over the apex of the lungs |
Pleural Cavity:
The pleural cavity refers to the potential space available between the visceral and parietal pleural layers. It contains serous pleural fluid, which lubricates the surfaces of the pleural layers and allows these layers to slide smoothly over each other during respiration. The pleural cavity provides the cohesion that keeps the lung surface pressed against the thoracic wall (this is because of the surface tension created by the pleural cavity).
Nerve supply of Lungs:
| Nerve supply of lungs Role of the sympathetic innervation Role of parasympathetic innervation | The branches of the sympathetic trunk and vagus nerve innervate the lungs and the airways. The respiratory center controls the lungs through the interaction of peripheral, central chemoreceptors and the pons and medulla oblongata. The sympathetic nervous system stimulates bronchodilation and slight vasoconstriction. Indirect vasodilation and bronchoconstriction result from parasympathetic nerve stimulation. |
| Nerve supply of pleura | The intercostal nerve innervates the costal and cervical portions of the parietal pleura, while the phrenic nerve supplies the diaphragmatic portion. The parietal pleura is the only pain-sensitive portion of the pleura. |
Blood supply:
| Blood supply of lungs Arterial supply Venous drainage | Blood is supplied to the non-respiratory airways, the pleura, and connective tissues through the bronchial arteries arising from the aorta, while the respiratory units (acini) receive blood from the pulmonary arteries. It is primarily the pulmonary venous system (right and left superior and inferior pulmonary veins) that drains the blood, but the bronchial veins drain the blood from the walls of the larger bronchi. Each pulmonary vein empties into the left atrium. |
| Blood supply of pleura | Bronchial circulation supplies the visceral pleura, and intercostal arteries supply the parietal pleura. |
Lymphatic drainage:
The lymphatic vessels that drain the lymph arise from two lymphatic plexuses:
| Lymphatic plexuses | Area drained |
| Superficial (subpleural) | drains the lung parenchyma |
| Deep | drains the structures of the lung root |
The tracheobronchial nodes (located around the bifurcation of the trachea and the main bronchi) empty both of these plexuses. The lymphatic fluid passes from here into the right and left bronchomediastinal trunks.
Pathologies (Diseases) of the Lungs:
| Diseases | Clinical Presentation |
| Pulmonary Collapse | A collapsed lung occurs when air gets into the pleural space, the area between the chest and the lung. As air builds up in the pleural space, it can press against the lung, causing it to collapse partially or completely. A collapsed lung also called a deflated lung or a pneumothorax requires immediate medical attention. |
| Hydrothorax | A pleural cavity containing a collection of non-inflammatory serous fluid is called hydrothorax. Such fluid tends to be clear and straw-colored. Hydrothorax can occur unilaterally or bilaterally. In addition to cardiac failure, cirrhosis of the liver and renal failure can cause hydrothorax. |
| Hemothorax | When the blood gets collected between the chest wall and lungs, the condition is known as hemothorax. |
| Pulmonary Embolism | During pulmonary embolisms (PE), blood clots form in blood vessels in the body (often in the legs); upon reaching a lung artery, it suddenly blocks blood flow. |
| pneumonia | As the name implies, pneumonia is an infection of the lung's air sacs (alveoli). Fluid or pus may fill up in the air sacs, resulting in symptoms such as a cough, fever, chills, and difficulty breathing. |
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