lung volumes - vital capacity - functional residual capacity - respiratory minute volume - dead space - spirometry - body plethysmography - peak flow meter The Respiratory System Among four-legged animals, the respiratory system generally includes tubes, such as the bronchi, used to carry air to the lungs, where gas exchange takes place. ... Human physiology is the science of the mechanical, physical, and biochemical functions of normal humans or human tissues or organs. ... It has been suggested that Gas exchange be merged into this article or section. ... The average pair of human lungs can hold about 6 litres of air, but only a small amount of this capacity is used during normal breathing. ... Vital capacity is the total amount of air that a person can expire after a complete inspiration. ... Functional Residual Capacity (FRC) is a medical term referring to the amount of air present in the lungs at the end of passive expiration. ... Respiratory minute volume (or minute ventilation, or flow of gas) is the volume of air which can be inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a persons lungs in one minute. ... In physiology, dead space is air that is inhaled by the body in breathing, but does not partake in gas exchange. ... Spirometry (meaning the measuring of breath) is the most common of the Pulmonary Function Tests (PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. ... Body Plethysmographs-To do a body plethysomograph, the person is enclosed in an airtight chamber often referred to as a body box. ... A peak flow meter is a small, hand-held device used to manage asthma by monitoring airflow through the bronchi and thus the degree of restriction in the airways. ...

ventilation (V) (positive pressure) breath (inhalation, exhalation) - respiratory rate - respirometer - pulmonary surfactant - compliance - hysteresivity - airway resistance In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. ... Positive Pressure ventilators help patients with respiratory problems to breathe easier. ... Breathing redirects here. ... Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing. ... It has been suggested that this article or section be merged with Minute volume. ... ... Diagram of the alveoli with both cross-section and external view Pulmonary surfactant is a surface-active lipoprotein complex formed by type II alveolar cells. ... Compliance of the lungs is an important measurement in respiratory physiology. ... “Hysteresivity” derives from “hysteresis”, meaning “lag”. It is the tendency to react slowly to an outside force, or to not return completely to its original state. ... Airway resistance is a concept used in respiratory physiology to describe mechanical factors which limit the access of inspired air to the pulmonary alveoli, and thus determine airflow. ...

pulmonary circulation - perfusion (Q) - hypoxic pulmonary vasoconstriction - pulmonary shunt Pulmonary circulation is the portion of the cardiovascular system which carries oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood back to the heart. ... In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. ... Hypoxic Pulmonary Vasoconstriction is the phenomenon when pulmonary arterioles vasoconstrict in the presence of hypoxia (low oxygen levels) without hypercapnia (high carbon dioxide levels). ... Pulmonary shunts exist when there is normal perfusion to an alveolus, but ventilation fails to supply the perfused region. ...

ventilation/perfusion ratio (V/Q) and scan - zones of the lung - gas exchange - pulmonary gas pressures - alveolar gas equation - hemoglobin - oxygen-haemoglobin dissociation curve (2,3-DPG, Bohr effect, Haldane effect) - carbonic anhydrase (chloride shift) - oxyhemoglobin - respiratory quotient - arterial blood gas - diffusion capacity - Dlco In respiratory physiology, the ventilation/perfusion ratio (or V/Q ratio) is a measurement used to the efficiency and adequacy of the matching of two variables:[1] V - ventilation - the air which reaches the lungs Q - perfusion - the blood which reaches the lungs A normal value is approximately 0. ... A ventilation/perfusion scan, also called a V/Q scan, is a medical test to measure the circulation of air and blood within a patients lungs. ... The zones of the lung proposed by West in 1964,[1] divide the lung into three vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), and the veins (Pv): #1: alveolar > arterial > venous #2: arterial > alveolar > venous #3: arterial > venous > alveolar The... Gas exchange or respiration takes place at a respiratory surface - a boundary between the external environment and the interior of the body. ... Following is a list of average partial pressures (in torr) for a human at rest: // The alveolar oxygen pressure is lower than the atmospheric O2 partial pressure for two reasons. ... The alveolar pO2 is not routinely measured but is calculated from blood gas measurements by the Alveolar gas equation: where: R is the Respiratory quotient (normally about 0. ... 3-dimensional structure of hemoglobin. ... The oxygen-haemoglobin dissociation curve plots the proportion of haemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis. ... 2,3-bisphosphoglycerate (2,3-BPG, also known as 2,3-diphosphoglycerate or 2,3-DPG) is a three carbon isomer of the glycolytic intermediate 1,3-bisphosphoglycerate and is present at high levels in the human red blood cell (RBC; erythrocyte) in the same molar concentration as hemoglobin. ... The Bohr effect is an adaption in animals to reduce the affinity of hemoglobin for oxygen as a response to an increase in blood carbon dioxide levels and a decrease in pH. It was first described by the Danish physiologist Christian Bohr in 1904. ... The Haldane effect is a property of hemoglobin first described by the British physician John Scott Haldane. ... Carbonic anhydrase (carbonate dehydratase) is a family of metalloenzymes (enzymes that contain one or more metal atoms as a functional component of the enzyme) that catalyze the rapid interconversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. ... The Respiratory Quotient is used in BMR calculations (basal metabolic rate) and is a form of indirect calorimetry. ... Arterial blood gas measurement is a blood test that is performed to determine the concentration of oxygen, carbon dioxide and bicarbonate, as well as the pH, in the blood. ... In biology, diffusion capacity is a measurement of the lungs ability to absorb and excrete gases, notably, oxygen and carbon dioxide. ... There are very few or no other articles that link to this one. ...

control of respiration: pons (pneumotaxic center, apneustic center) - medulla (dorsal respiratory group, ventral respiratory group) - chemoreceptors (central, peripheral) - pulmonary stretch receptors - Hering-Breuer reflex Control of ventilation refers to the physiological mechanisms involved in the control of ventilation (physiology). ... Position of the pons in the human brain The pons (sometimes pons Varolii after Costanzo Varolio) is a knob on the brain stem. ... The pneumotaxic center of the upper pons antagonises the apneustic centre. ... The apneustic center of the lower pons appears to promote inspiration by stimulation of the I neurons in the medulla oblongata providing a constant stimulus. ... The medulla oblongata is the lower portion of the brainstem. ... The dorsal repiratory group is found in many types of fish and marine mammals. ... The ventral respiratory group is a group of neurons in the medulla which initiates inhalation. ... A Chemosensor, also known as chemoreceptor, is a cell or group of cells that transduce a chemical signal into an action potential. ... Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface, are sensitive to the pH of their environment. ... Peripheral chemoreceptors act most importantly to detect variation of the oxygen in the arterial blood, in addition to detecting arterial carbon dioxide and pH. These nodes, called the aortic body and carotid body, are located on the arch of the aorta and on the common carotid artery, respectively. ... Pulmonary stretch receptors are mechanoreceptors found in the lungs. ... The Hering-Breuer reflex is a reflex triggered to prevent overinflation of the lungs. ...

high altitude - oxygen toxicity - hypoxia There are several effects of high altitude on humans: The percentage saturation of hemoglobin with oxygen determines the content of oxygen in our blood. ... Oxygen toxicity or oxygen toxicity syndrome is severe hyperoxia caused by breathing oxygen at elevated partial pressures. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...