Explore chapters and articles related to this topic
Health Effects Due to Particle Matter
Published in Ko Higashitani, Hisao Makino, Shuji Matsusaka, Powder Technology Handbook, 2019
Yasuo Morimoto, Toshihiko Myojo
The primary purpose of the respiratory organ is to act as a gas exchange mechanism. Figure 7.1.1 shows a schematic anatomy of the lung. Air inspired through the nose or the mouth enters the larynx and then the trachea, which is divided into two main bronchi. The bronchial tubes repeatedly divide and diminish in diameter with bifurcation, the smallest tubes being called bronchioles. The diameter of the main bronchi and terminal bronchioles are 1.2 cm and 0.5 mm, respectively. These dimensions and numbers have major implications with respect to deposition and clearance of particles entering the lung while entrained in respired air. Terminal bronchioles lead into the respiratory bronchioles and then into the respiratory space which is composed of a number of alveoli. A very thin layer of venous blood is circulated through the pulmonary capillaries, which are arranged in a network over the surface of approximately 300 million air-containing alveoli. The total effective gas exchange surface of the alveoli has been estimated at 100 m2. The alveolar capillary wall separating the blood from the gas phase is on average 0.55 µm in thickness. During the passage of venous blood over the surface of this barrier, the rapid movement of oxygen from the air into the blood and of carbon dioxide out of the blood into the air phase is carried out by gas diffusion.
Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2016
David J. Baker, Naima Bradley, Alec Dobney, Virginia Murray, Jill R. Meara, John O’Hagan, Neil P. McColl, Caryn L. Cox
Physiologically, four phases of respiration are recognised:Ventilation: the movement of air to and from the lungs.Distribution: air entering the lungs is distributed to all parts including the small air sacs (alveoli) where gas transfer to and from the blood takes place.Diffusion: the oxygen from the air diffuses through the walls of the alveoli to the adjacent blood vessels and carbon dioxide from the blood vessels diffuses back in to the alveoli.Blood rich in carbon dioxide and low in oxygen is pumped to the lungs via the pulmonary arteries, by the right ventricle of the heart. Blood low in carbon dioxide but loaded with oxygen is returned to the heart via the pulmonary veins. Matching of ventilation and perfusion (i.e. blood supply to the alveoli – air sacs) within the lung ensures normal gas exchange.
Flexible and Wearable Chemical Sensors for Noninvasive Biomonitoring
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Hiroyuki Kudo, Kohji Mitsubayashi
Humans consume oxygen and release carbon dioxide by the exchange of gases in the lungs. Gas exchange takes place between millions of alveoli in the lungs and the capillaries that envelop them. The partial pressure of oxygen in arterial blood (PaO2) is known to reflect the severity of lung disorders such as pulmonary embolism or atelectasis. It is also used in the diagnosis, treatment and management of respiratory depression. This parameter is usually measured by obtaining blood from an artery. This involves puncturing an artery, often at the wrist, and drawing a small volume of blood with a syringe. Normally, PaO2 is kept within a range of 80 to 100 mmHg, and abnormal PaO2 values are seen in hypoxemia or hyperoxemia. At a PaO2 of less than 60 mmHg, supplemental oxygen should be administered. In premature neonates, it is especially important to monitor arterial oxygen levels continuously to ensure they are maintained at normal levels as these infants have immature cardiopulmonary systems.
Mathematical analysis of oxygen and carbon dioxide exchange in the human capillary and tissue system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Ahsan Ul Haq Lone, M. A. Khanday
The human respiratory system has two main functions: oxygen intake from the surrounding air to the body, and to exhale carbon dioxide from the blood to outside air. Those transfers are achieved through passive diffusion across a membrane which separates the gaseous air and the liquid blood, at an instantaneous rate by means of the difference in partial pressures, the area of the exchange surface, and its properties in terms of diffusion (Guyton and Hall 2011; West 2011). As this diffusion tends to reduce the partial pressure difference, a constant renewal must be made on both sides of the membrane. Renewal of air is achieved by the ventilation process, which consists of in periodic inspiration-expiration cycles that provide the inside of the lung with fresh air, whereas venous blood is periodically pumped onto the exchange zone by the heart. The exchange area is the boundary of a huge collection of small cavities (around 300 million units), called alveoli, which makes an exchange area of about 100 m2 (Guyton and Hall 2011; West 2011; Tortora and Derrickson 2012; Nunn 2013). Each of this alveolus is surrounded by a network of very small blood vessels, called capillaries, whose diameter is about 5–10 μm (Guyton and Hall 2011; West 2011). Gas exchange occur through the alveolar-capillary membrane, which is less than a micrometre wide (West 2011; Tortora and Derrickson 2012). The alveoli are connected to the outside world through the respiratory tract, which is an assembling of interconnected pipes following a dyadic-tree structure.
Inspiratory muscle training effects on oxygen saturation and performance in hypoxemic rowers: Effect of sex
Published in Journal of Sports Sciences, 2019
Christos Riganas, Zacharoula Papadopoulou, Nikos V. Margaritelis, Kosmas Christoulas, Ioannis S. Vrabas
Regarding the effects of this phenomenon on exercise capacity, Powers, Lawler, Dempsey, Dodd, and Landry (1989) suggested that EIAH limits VO2max in endurance athletes who experience EIAH by 1% for each 1% decrease in oxygen arterial saturation. This phenomenon is not surprising considering that [(A-a)DO2] has been demonstrated to increase almost linearly with increasing oxygen uptake, which implies an alteration in gas exchange during exercise. Several mechanisms have been proposed to explain this gas exchange failure during EIAH. Contemporarily, ventilation-perfusion inequality/mismatching (VA/Q) and pulmonary diffusion limitations are considered the major contributors to EIAH compared to the inadequate hyperventilatory compensation mechanism and the veno-arterial shunt, which are thought to minimally add to EIAH (Boutellier, Buchel, & Kundert et al., 1992; Dempsey, 1984; Gale, Torre-Bueno, Moon, Saltzman, & Wagner, 1985; Hopkins, 2006; Hopkins, McKenzie, Schoene, Glenny, & Robertson, 1994; Inbar, Weinstein, Kowalsky, Epstein, & Rotstein, 1993; O’ Kroy, 1992; Powers, 1993; Powers et al., 1988; Torre-Bueno et al., 1985).
Organizational Diseases
Published in Cybernetics and Systems, 2020
Mario Iván Tarride, Brenda Villena, Julia González
As explained by Thibodeau and Patton (2007), the function of the lungs is to take the air that comes from the upper respiratory tract through the ducts of the bronchial tree and pass it through the alveoli to the blood capillaries, where the gas exchange with the blood takes place, i.e., giving it oxygen and removing carbon dioxide from it.