Lung Anatomy PDF

# Lunger ## Hilum pulmonis - Hilum pulmonis is a comma-shaped area without pleura, where the lung root enters the lung. - Hilum is the only place on the lung surface that is not covered by pleura. ## Heart impression - The heart makes an impression on both the right (8) and left (12) lungs, but...

# Lunger ## Hilum pulmonis - Hilum pulmonis is a comma-shaped area without pleura, where the lung root enters the lung. - Hilum is the only place on the lung surface that is not covered by pleura. ## Heart impression - The heart makes an impression on both the right (8) and left (12) lungs, but it is more prominent on the left lung. - The esophagus forms a groove (6) on the right lung and the aorta (13) on the left lung. ## Lung lobes - Lungs are divided into lobes, and the lobes are separated by deep fissures (2) that almost reach the hilum pulmonis. - The right lung has three lobes: - An overlap (5) - A middle lobe (4) - A lower lobe (3). - The left lung has only two lobes, an overlap (10) and a lower lobe (11). - The right lung has two fissures, the left lung has one. ## Bronchus, Arterie, Vener (BAVfra) - The components of the lung root are easily remembered by the name 'BAVfra'. - The order is Bronchus (10), Arterie (9) and Vener (8). ## Trachea and bronchi - The trachea (1) divides into two main bronchi (2), which in turn divide into lobe bronchi (3). - The number of lobe bronchi in each lung corresponds to the number of lobes: three on the right and two on the left. ## Segmentbronchi - Each lobe bronchus gives rise to a number of segment bronchi (4), which supply a specific lung segment. - These segment bronchi further divide into finer and finer branches. - Only some of the segment bronchi (4) are marked. - Fine branches that enter the lung lobules and branch there are called bronchioli (5). - Each lobule receives one bronchiolus, which is about 1 millimeter in diameter. ## Branching of the bronchial tree - The branching of the bronchial tree reflects the division of the lungs into different units. - The largest 'unit' is the lobes, which are supplied by the lobe bronchi (3). - The next 'unit' is the segments, which are not visibly demarcated on the surface. - Each segment is supplied by a segment bronchus (4). - There are a limited number of segments: 10 on the right and 9 on the left. - The smallest unit is the 'lobule'. ## Lobulus - Each lobule is supplied by a bronchiolus (5) which enters the lobule and branches. - Lobules appear as 1 to 2 centimeter large areas on the lung surface, and there are a large number of them. - Cartilage and glands are absent from the wall of the bronchiolus where it enters the lobule. - Scattered lung alveoli (6) appear on the wall of the bronchioli after the bronchioli. - Alveolar ducts (2) follow. These are almost entirely covered by alveoli. - Alveolar ducts terminate in alveolar sacs (3), which are blind-ended and have walls exclusively consisting of alveoli (6). ## Alveolar sacs - Alveolar sacs (2) are small vesicles that are just visible to the naked eye. - They are bowl- or bell-shaped, and their wall contains a dense capillary network (1) which is separated from the air in the alveolar lumen by flat cells that line the alveolar wall (not shown). - Amorphous ground substance and various connective tissue fibrils are found between the capillaries in the alveolar wall. - The dense capillary network makes the exchange surface between alveolar air and blood very large. - The respiratory surface, which corresponds to the alveolar area, has an extent of about 55-80 square meters. ## Blood circulation - Blood is carried to the capillary network in the alveolar wall through branches from the pulmonary artery, the truncus pulmonalis, which originates from the right ventricle. - In the lung, the arterial branches (5) follow the bronchial tree throughout the entire way (fig. 28), both outside and in the lobules. - Once the blood has been oxygenated in the capillary network in the alveolar wall, it is carried through the veins (4), which do not follow the bronchial tree, to the pulmonary veins, vv. pulmonales, which empty the oxygenated blood into the left atrium. ## The functional vascular system - The truncus pulmonalis and the vv. pulmonales are part of the functional vascular system in the lungs. ## The nutritive vascular system - The nutritive vascular system of the lungs supplies the bronchial wall and connective tissue in the lungs. - The nutritive system consists of small arteries, aa. bronchiales (right line from 11), from the aorta thoracica (9), and veins, vv. bronchiales, which drain into the azygos system (11) along the vertebral column, in the posterior mediastinum. ## The small circulation - The lungs are connected to the small circulation, that is, between the truncus pulmonalis and the vv. pulmonales. - This location is related to function, not nutrition. - The blood that nourishes the tissue in the lungs comes from the aorta, and it returns to veins in the azygos system (11), which acts as anastomoses between the superior vena cava (1) and the inferior vena cava (6). ## Pleura - Each lung is surrounded by a pleura. - It is a serous membrane that consists of a visceral (2) and a parietal layer (3). - The visceral layer covers the lung (5), except at the hilum pulmonis (1), where it joins the parietal layer.