It contains superior and inferior bronchopulmonary segments. Above and behind the cardiac impression is a triangular depression named the hilum. The hilum is the root of the lung where that contains structures that supply the lungs with blood, lymph fluid, and innervation, such as the pulmonary vein, pulmonary artery, pulmonary nerves, and lymphatic vessels. These structures are enclosed by pleura. There is a hilium for each of the lungs found in the mediastinum backside of the lungs.
The hilium is thinner in the left lung compared to the right lung because it lies between the cardiac notch and the groove for the aorta. The hilium is important because it is the primary way in which the respiratory system links with the cardiovascular and nervous systems. Pulmonary circulation transports oxygen-depleted blood away from the heart to the lungs and returns oxygenated blood back to the heart.
Bronchial circulation by the bronchial arteries supplies blood to the tissues of the bronchi and the pleura, and is considered part of systemic circulation. The right side of the heart deals with pulmonary circulation. At the end of systemic circulation, the veins take blood back to the heart through the vena cava. The vena cava fills the right atrium with blood, which then ejects blood into the right ventricle by passing through the tricuspid valve.
After blood fills in the right ventricle, it contracts and pumps the blood through the pulmonary valve, and into the pulmonary arteries. There are two pulmonary arteries one for each lung that bring the deoxygenated blood to the lungs through the hilium. The arteries branch into the capillaries of the alveoli. Capillaries are the thinnest and smallest type of blood vessel, and they supply oxygen to individual tissues everywhere in the human body.
Gas exchange occurs by passive diffusion in the alveoli, so that dissolved oxygen enters the capillaries, while carbon dioxide leaves pulmonary circulation. The oxygenated blood then leaves the lungs through pulmonary veins also contained in the hilium , which return the blood to the left side of the heart, completing the cycle of pulmonary circulation.
This blood then enters and fills inside the left atrium, which pumps it through the mitral valve also called bicuspid into the left ventricle. The blood fills inside the left ventricle and is then pumped through the aortic valve into the aorta, which marks the beginning of systemic circulation. Systemic circulation and pulmonary circulation form the overall cycle of the circulatory system: transporting oxygen throughout the body.
Pulmonary circuit : Diagram of pulmonary circulation. Oxygen-rich blood is shown in red; oxygen-depleted blood in blue. While the cycle of pulmonary and systemic circulation is a well designed and effective system, it is not immune to certain problems. The most serious issue in pulmonary circulation is a pulmonary embolism, which is where a blood clot travels to the lung and causes an infarction of the lung tissue death from lack of oxygen.
These blood clots typically originate in the deep veins of the legs part of systemic circulation as a result of blood pooling from injury or immobilization.
As the veins of the leg are on their way to the right side of the heart, the clots are less likely to break up before they reach pulmonary circulation.
When the clot reaches the pulmonary artery, it obstructs the flow of blood into the lung, which causes the alveoli in the effected lung to die as a result. This results in an increase in aveolar dead space and decreased perfusion, leading to shortness of breath and chest pain and can be fatal if not treated in time by fibrinolytics medications that dissolve the clot.
Privacy Policy. Skip to main content. Respiratory System. URL of Article. There are a few differences between the two lungs: The right lung is larger in volume than the left lung , with a larger transverse dimension due to the heart on the left but a shorter longitudinal dimension due to the liver causing the right hemidiaphragm to be higher than the left. The right main bronchus also differs to the left main bronchus , as it is longer, larger caliber and more vertical. The right lung has 2 fissures : the oblique and horizontal fissures.
The right lung contains 3 lobes and 10 bronchopulmonary segments : right upper lobe apical segment posterior segment anterior segment right middle lobe lateral segment medial segment right lower lobe superior segment anterior segment medial segment lateral segment posterior segment For a detailed description of lung anatomy and function, see the lung article here. Clinically oriented anatomy. Read it at Google Books - Find it at Amazon. Related articles: Anatomy: Thoracic.
Chronic bronchitis and emphysema are considered COPD diseases. About Sometimes, those with COPD get lung transplants, replacement lungs garnered from organ donors, to save their lives. Research is also being done on growing new lungs from stem cells. Currently, stem cells extracted from the patient's blood or bone marrow are being used as a treatment to heal damaged lung tissue. Lung infections , such as bronchitis or pneumonia, are usually caused by viruses, but can also be caused by fungal organisms or bacteria, according to Ohio State University.
Some severe or chronic lung infections can cause fluid in the lungs and other symptoms such as swollen lymph nodes, coughing up blood and a persistent fever. Being overweight can also affect the lungs. One of the best ways to promote good lung health is to avoid cigarette smoke because at least 70 out of the 7, chemicals in cigarette smoke damages the cells within the lungs. According to the Mayo Clinic, people who smoke have the greatest risk of lung cancer. The more a person smokes, the greater the risk.
Those who smoke are 15 to 30 times more likely to get lung cancer according to the Centers for Disease Control and Prevention. If a person quits, their lungs can heal from much of the damage, said Dr. Norman Edelman, a senior scientific adviser for the American Lung Association and a specialist in pulmonary medicine. The Rush University Medical Center also suggests practicing deep breathing exercises, staying hydrated and regular exercise to keep the lungs healthy.
Parsons also recommends having homes tested for radon. Dilation and constriction of the airway are achieved through nervous control by the parasympathetic and sympathetic nervous systems. The parasympathetic system causes bronchoconstriction , whereas the sympathetic nervous system stimulates bronchodilation. Reflexes such as coughing, and the ability of the lungs to regulate oxygen and carbon dioxide levels, also result from this autonomic nervous system control.
Sensory nerve fibers arise from the vagus nerve, and from the second to fifth thoracic ganglia. The pulmonary plexus is a region on the lung root formed by the entrance of the nerves at the hilum. The nerves then follow the bronchi in the lungs and branch to innervate muscle fibers, glands, and blood vessels. Each lung is enclosed within a cavity that is surrounded by the pleura. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum.
The pleurae consist of two layers. The visceral pleura is the layer that is superficial to the lungs, and extends into and lines the lung fissures Figure 2. In contrast, the parietal pleura is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm. The visceral and parietal pleurae connect to each other at the hilum. The pleural cavity is the space between the visceral and parietal layers.
The pleurae perform two major functions: They produce pleural fluid and create cavities that separate the major organs. Pleural fluid is secreted by mesothelial cells from both pleural layers and acts to lubricate their surfaces. This lubrication reduces friction between the two layers to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall.
This adhesive characteristic of the pleural fluid causes the lungs to enlarge when the thoracic wall expands during ventilation, allowing the lungs to fill with air. The pleurae also create a division between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection.
The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette.
Second-hand smoke, which is a combination of sidestream smoke and the mainstream smoke that is exhaled by the smoker, has been demonstrated by numerous scientific studies to cause disease.
At least 40 chemicals in sidestream smoke have been identified that negatively impact human health, leading to the development of cancer or other conditions, such as immune system dysfunction, liver toxicity, cardiac arrhythmias, pulmonary edema, and neurological dysfunction. Furthermore, second-hand smoke has been found to harbor at least compounds that are known to be toxic, carcinogenic, or both. Some major classes of carcinogens in second-hand smoke are polyaromatic hydrocarbons PAHs , N-nitrosamines, aromatic amines, formaldehyde, and acetaldehyde.
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