Lung compliance

Examples of Lung compliance in the following topics:

• Factors Affecting Pulmonary Ventilation: Compliance of the Lungs

  • Lung compliance refers to the magnitude of change in lung volume as a result of the change in pulmonary pressure.
  • Compliance depends on the elasticity and surface tension of the lungs.
  • Compliance is inversely related to the elastic recoil of the lungs, so thickening of lung tissue will decrease lung compliance.
  • A low lung compliance means that the lungs are "stiff" and have a higher than normal level of elastic recoil.
  • A high lung compliance means that the lungs are too pliable and have a lower than normal level of elastic recoil.

• Lung Cancer

  • Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung.
  • Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung.
  • Most cancers that start in lung, known as primary lung cancers, are carcinomas that derive from epithelial cells.
  • The main types of lung cancer are small cell lung carcinoma (SCLC), also called oat cell cancer, and non-small cell lung carcinoma (NSCLC).
  • Accounting for 25% of lung cancers, squamous cell lung carcinoma usually starts near a central bronchus.

• Lungs

  • The lungs are cone-shaped—the apex refers to the top of the lung, while the base refers to the bottom of the lung.
  • The right lung is larger than the left lung, and the left lung contains the cardiac notch, a concave impression that the heart lies against.
  • The lungs are divided into lobes by fissures on the outer surface of the lung, and divide further into segments and finally into hexagonal lobules, the smallest divisions of the lungs.
  • The elastic recoil of the lungs automatically pulls the lungs inward during exhalation.
  • The major function of the lungs is gas exchange, which occurs in the alveoli of the lung.

• Lobes, Fissures, and Lobules

  • There are three lobes in the right lung and two in the left lung.
  • The right lung is divided into three lobes.
  • It is a small, tongue-like projection of the left lung that is analogous to the middle lobe of the right lung.
  • There is a hilium for each of the lungs found in the mediastinum (backside) of the lungs.
  • The right lung has three lobes and the left lung has two.

• Blood Flow in the Lungs

  • Pulmonary circulation in the lungs is responsible for removing carbon dioxide from and replacing oxygen in deoxygenated blood.
  • From the right ventricle of the heart, blood is pumped through the pulmonary semilunar valve into the left and right pulmonary arteries (one for each lung) and travels through the lungs.
  • Air is inhaled through the nose or the mouth and fills the lungs.
  • The alveoli are the site of oxygen and carbon dioxide exchange in the lungs.
  • Outline the path of pulmonary circulation: blood flow in the lungs

• Lung Capacity and Volume

  • Lung volumes and capacities refer to phases of the respiratory cycle; lung volumes are directly measured while capacities are inferred.
  • Capacity of the lungs generally refers to the total amount of volume of air inside the lungs at certain phases of the respiratory cycle.
  • In general, measuring lung capacity is important because it serves as potentially the best indicator of lung health through quantifying the functional ability of the lungs to cycle air.
  • It is not very reduced in those with obstructive lung diseases.
  • Other important lung volumes related to lung capacity are residual volume (RV) and total lung capacity (TLC).

• Development of the Respiratory System

  • Lung development can be divided into distinct stages: the pseudoglandular period, the canalicular period, and the terminal saccular period.
  • The development of the lungs is divided into three stages.
  • By the end of this period, all major lung elements, except those required for gas exchange (e.g. alveoli), have appeared.
  • Figure 1 shows the right and left lung buds from which the bronchi and lungs will develop.
  • Lung buds from a human embryo of about four weeks, showing commencing lobulations.

• Chronic Obstructive Pulmonary Disease (COPD)

  • The diagnosis of COPD requires lung function tests and a chest X-ray .
  • A little of the air of the previous breath remains within the lungs when the next breath is started, resulting in an increase in the volume of air in the lungs, a process called dynamic hyperinflation.
  • A high-resolution computed tomography scan of the chest may show the distribution of emphysema throughout the lungs and can also be useful to exclude other lung diseases.
  • Enlarged view of lung tissue showing the difference between healthy lung and COPD
  • Note the small size of the heart in comparison to the lungs.

• Functional Anatomy of the Respiratory System

  • The respiratory system include lungs, airways and respiratory muscles.
  • Ventilation is the rate at which gas enters or leaves the lung.
  • Minute Ventilation (VE): The amount of air entering  the lungs per minute.
  • The lungs have high degree of elastic recoil, so they rebound from the stretch of inhalation and air flows out until the pressures in the lungs and the atmosphere reach equilibrium.
  • The reason for the elastic recoil of the lung is the surface tension from water molecules on the epithelium of the lungs.

• Aging and the Respiratory System

  • In mammals, breathing is produced by a flattening of the diaphragm and lung expansion.
  • Lung elasticity declines with aging.
  • When the diaphragm relaxes, air is expelled by the lung's elasticity.
  • As alveoli die, the number of lung capillaries decreases and the elastin of the lungs begins to break down, causing loss of pulmonary elasticity.
  • Emphysema is a common lung disease in the elderly.