Moreover, mitochondria are deeply implicated in apoptosis and ageing. Mitochondrial dysfunction is the cause of severe, often maternally inherited diseases. Not surprisingly, mitochondria play a fundamental role in human health. They also act in calcium signaling, stress responses and generally as cellular signaling hubs. Apart from cellular respiration and ATP synthesis, mitochondria have numerous other essential functions, including the production of NADH and GTP in the citric acid cycle, the biosynthesis of amino acids, heme groups and iron-sulfur clusters or the synthesis of phospholipids for membrane biogenesis. These are the products of ATP hydrolysis at the sites where energy is needed in the cell. ATP is generated by the mitochondrial ATP synthase from ADP and phosphate ions. ATP is produced on a massive scale in the human body, amounting to 50 kg per day in a healthy adult, but considerably more in a long-distance runner. These functions include force generation (for example, in muscle contraction and cell division), the biosynthesis, folding and degradation of proteins, and the generation and maintenance of membrane potentials. In all eukaryotes that do not depend on photosynthesis, the mitochondria are the main source of adenosine triphosphate (ATP), the energy-rich compound that drives fundamental cell functions. As the distance from the light source to the object to be illuminated increases, the illuminance decreases in the square.Mitochondria are the powerhouses of the cell. When measuring, make sure that the light meter is placed at working height. With a light meter you can measure the lux value of any surface or space. A lamp that gives the same number of lux at three meters distance than a lamp measured at one meter is much more powerful than the one measured on a meter. Be careful when making a comparison between two lamps. Lux can be measured from different distances. The number of lux is thus found as the quotient of the total received luminous flux, expressed in lumens, and the size of the illuminated area expressed in square meters therefore 1 lux = 1 lumen / m².

The lux thus corresponds to the illuminance that is obtained when each square meter of the considered surface receives a luminous flux of one lumen. The lux (symbol lx), latin for light, is a unit of illumination: 1 lux is the illuminance produced by 1 candela on a surface perpendicular to the light rays at a distance of 1 meter from the source. The smaller the angle of radiation in which the light is emitted, the higher the luminous intensity (with constant luminous flux). An incandescent lamp gives a luminous flux of approximately 12 lm / W. The luminous flux depends on the power of the source and on the color of the light. If one sees a part of a light beam, that part has a smaller luminous flux (in lumen) but (in principle) the same luminous intensity (in candela) as the whole beam. Light intensity is a measure of the light density. Luminous flux is a measure of the total amount of light in a light beam. Lumen is therefore the unit to measure the brightness of a light source independently of the direction of the light beam. Luminous flux takes into account the sensitivity of the eye to the visible part of the electromagnetic radiation. It measures the total amount of light emitted by a light source in all directions. The lumen (symbol: lm) is the unit for luminous flux.

Lumen definition biology