Lung anatomy, lobes, and fissures

Hello students and friends, today we are going to discuss lung anatomy, here we also learn what are bronchopulmonary segments, lobes of the lungs, fissures of the lungs, and also about its covering (pleura). 

Tests, treatment, and conditions are also included in today’s topic. So let us start with its gross anatomy.

Gross anatomy

>Lungs are located in the chest on both sides of the heart in the rib cage(thoracic cavity).

>They are conical in shape.

>They are narrowly rounded – Apex at the top.

>They have a broad base – rest on the diaphragm (matching its concavity)

>The apex of the lung extends into the root of the neck and reaches shortly above the level of the sternal end of the 1st rib.

>The medial surface of the lungs faces towards the center of the chest and lies against the heart, great vessels, and the carneae.

Great vessels [IVC(Inferior vena cava), pulmonary artery, PV(pulmonary vein), SVC(superior vena cava), and aorta] where the two main bronchi branch off from the base of the trachea.

Lungs are the central part of the respiratory system.

~Central recession -> hilum at the root of both the lungs.

~Blood vessels and Airways pass into the lungs from the hilum.

~Bronchopulmonary lymph nodes are also present on the hilum.

Blood supply through the pulmonary artery(deoxygenated blood to the lungs through hilum)- 1 for each lung.

Pleura » 2 serous membranes  

✓the outer parietal pleura lines the inner wall of the rib cage.

✓the inner visceral pleura directly lines the surface of the lungs.

″ Pleural fluid is being in the pleural cavity. ″

Each lung is divided into lobes by the invaginations(folds) of the pleura as fissures. The fissures are double folds of pleura that section the lungs and help their expansion.

Bronchopulmonary segments :

✓The lung has three lobes and is further divided into a bronchopulmonary segment based on the location of bronchioles.

Right lung:

Superior lobe

1) Apical segment

2) Posterior segment

3) Anterior segment

Middle lobe

1) Medial basal segment

2) Lateral segment

Inferior lobe

1) Superior segment

2) Posterior basal segment

3) Anterior basal segment

4) Lateral basal

5) Posterior basal

Left lung:

Superior lobe:

1) Apical 

2) Posterior segment

3) Anterior segment

4) Superior lingular segment

5) Inferior lingular segment

Inferior lobe:

1) Superior basal segment

2) Lateral basal segment

3) Anterior middle segment

4) Medial basal segment

5) Posterior basal segment

Lung fissures:

1) oblique fissure

• right and left lung

• starts at 3rd thoracic spine cutting the midaxillary line in the 5th and ending at the six costal cartilage 3 inches from the midline.

2) transverse fissure

• arises at the fourth costal cartilage

• runs horizontally to meet the oblique features in the midaxillary line in the 5th rib.

• right lung

Pleura

1) visceral pleura

2) parietal pleura

Parietal pleura

1) costal pleura

• lines thoracic wall ( ribs intercostal spaces ).

2) mediastinal pleura

• lines the corresponding surface of the mediastinum.

• reflected over the root of the lung.

• become continuous with visceral pleura around it.

3) cervical pleura

• extends into neck about 2 inches above first costal cartilage and one inch above medial one-third clavicle.

4) diaphragmatic pleura

•lines the superior surface of the diaphragm.

>The lungs contain the respiratory tract and its lining, which terminate in alveoli the tissue in between and veins, nerve, artery, and lymphatic vessels.

The respiratory tracks begin with the trachea and bronchi.

These structures are lined with columnar epithelial cells that possess cilia.

>Goblet cells are present which produce mucus.

Club cells with short microvilli and they do not have Cilia and action is similar to macrophages.

Club cells are cubicle and dome-shaped and secrete mucus.

Cartilage rings are present which helps to maintain stability.

The respiratory tract end in lobules.

These consist of a respiratory bronchiole that branches into alveolar ducts and alveolar sacs which in turn divides into alveoli.

Alveoli consist of two types of alveolar cell and alveolar macrophages.

Two types of cells are known as type 1 and type 2 alveolar cells (pneumocytes).

Type 1 cells provide 95% of the surface area of each alveolus ( they are flat & squamous).

Type 1 are squamous epithelial cells that make up the alveolar wall structure.

They have extremely thin walls from that gas exchange that may easily occur.

Makeup alveolar septa which separate each alveolus.

The septa consist of the epithelial lining and associated basement membranes.

Type 1 cells are not able to divide and consequently relay on differentiation from type II cells.

Type 2 cell  generally cluster in the corners of the alveoli {they are cuboidal in structure}

Type 1 and type 2 buildup the walls and septa of alveoli.

Type 2 are larger and they line the alveoli and produce and secrete epithelial lining fluid and surfactant.

Type 2 cells are able to divide and differentiate to type 1 cells.

Cells occur in a rough ratio of 1:1 & 6:4.

LUNG CONDITIONS-

1- Emphysema

2-COPD[chronic obstructive pulmonary disease]

3-Asthma

4-Acute Bronchitis

5-Pleural effusion

6-Bronchiectasis

7-Lung cancer

9-ARDS[acute respiratory distress syndrome]

10-Pneumothorax

11-Severe acute respiratory syndrome [SARS]

TESTS FOR LUNGS-

1- Chest X-Ray

2- Spirometry

3-Lung biopsy

4-Bronchoscopy

5-Sputum culture

TREATMENT-

1-Thoracostomy

2-Antibiotics

3-Bronchodilators

4-Corticosteroids

5-Lung transplant

6-Vasodilators

7-In case of lung cancer-chemotherapy and radiation therapy.

Hope you all find this helpful for you, if you have any query related to this topic or any other topic then you all are free to contact me via contact us or you can also ask your doubts on the comment box. Thank you! 

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