The lungs are one of the most important organs present in the body. These are the organs of the respiratory system that are responsible for helping us breathe, and thus, actually form the main part of the respiratory system. The lungs are divided into the right lung and left lung. The right lung has three lobes, whereas the left lung has only two lobes. However, all the lobes help in the exchange of gases and aid breathing.
The nose leads into the trachea, which then splits into two bronchi, which in turn branch into various bronchioles. These bronchioles then lead into small alveoli, which is where the exchange of air takes place. The lungs are basically made up of parenchymatous tissue that is present in this form on the right and left, which thus, constitutes the right and left lungs. Each lung has a specific number of lung lobes.
Right Lung
The right lung weights more than the left lung…
The right lung is shorter than the left lung by about five centimeters. This is due to the diaphragm rising higher on the right side so as to accommodate the liver. However, the right lung is broader due to the inclination of the heart on the left side. Due to this reason, the total capacity, volume and weight of the right lung is more than that of the left lung.
The right lung has three lung lobes:
- Superior lobes
- Middle lobes and
- Inferior lobes
These are separated from each other by the interlobular fissures. One of these fissures, the oblique fissure, separates the inferior lobe of the lung from the middle and superior lobes. This fissure corresponds closely with the fissure in the left lung. However, its direction is more vertical and it cuts the lower border of the right lung around 7.5 cm behind its anterior extremity. The other fissure, which is the horizontal fissure, separates the superior from the middle lobe. This fissure begins in the previous fissure near the posterior border of the lung and running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage. On the mediastinal surface of the lung, it may be traced backwards to the hilum.
The middle lobe is the smallest of all the lung lobes of the right lung. It is wedge-shaped and includes the lower part of the anterior border and the anterior part of the base of the lung. The right upper lobe is one of the largest lobes of the lungs and is located on the anterior surface of the chest, taking up most of the space here. On the other hand, the inferior right lobe is primarily located towards the posterior surface of the chest and very little is projected onto the anterior chest.
Left Lung
The left lung is two lobed…
The left lung lacks a proper middle lobe. The reason why there is no middle lobe, which makes the left lung smaller than the right, is that it makes room for the heart as the human heart is placed slightly towards the left side of the chest.
The left lung is divided into two lobes:
- Superior lobe and
- Inferior lobe
The upper and lower lobe is divided by a fissure known as an oblique fissure. This fissure extends from the costal to the mediastinal surface of the lung, both above and below the hilum. This fissure begins on the mediastinal surface of the lung at the upper and posterior part of the hilum and then runs backwards and upwards to the posterior border which it crosses at a point about six centimeters below the apex of the left lung.
The superior lobe, which is the larger of the two lobes of the lungs, lies above and in front of this fissure and includes the apex, the anterior border and a part of the costal surface and the greater part of the mediastinal surface of the lung. The inferior lobe is the smaller of the two lung lobes and is situated below and behind the fissure and comprises almost the entire base, a large portion of the costal surface and a greater part of the posterior border. The lobe that is missing or is not present in the left lung when compared to the right lung is the middle lobe. Instead there is a small projection of the upper lobe of the left lung which is known as lingula. Lingula means ‘little’ in Latin. It is also known as tongue of the lung because of its shape. It is further divided into two segments, upper or superior and lower or inferior.
Lobes of the lungs further divide into lobules. There are approximately 130,000 lobules in the lungs which have bronchi branching out of them. These bronchi further branch and finally get down to air sacs which are known as alveoli, where gaseous exchange takes place. So we can say that all the lung lobes have the same function of aiding in respiration and exchange of gases. Despite the structural differences, all the lobes are equally susceptible to various infections and diseases due to internal and external factors. Though there are effective medications and surgeries to treat lung diseases, some diseases may even be life-threatening. Hence, it is very important to take care of the lungs and avoid smoking and other factors which may trigger dangerous conditions.
