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Countercurrent flow occurs when deoxygenated blood moves through the gill in one direction while oxygenated water moves through the gill in the opposite direction. This mechanism maintains the concentration gradient thus increasing the efficiency of the respiration process as well and prevents the oxygen levels from reaching an equilibrium .
Later in the day when solar radiation is reduced and during the night when there is no light, respiration still occurs in the absence of gross primary production resulting in net consumption of O 2 and production of CO 2. Data for this figure are from Harp Lake on August 1, 2014. [5]
The roof of the lung is highly vascularised, and it is through this surface that gas exchange occurs. The majority of pulmonates are fully terrestrial. Most have the typical lung arrangement described above, but in the Athoracophoridae , the mantle cavity is replaced by a series of blind tubules, while the Veronicellidae respire through their ...
Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the diffusion and transport of metabolites between the organism and the external environment.
Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into ATP, and then release waste products. [1] Cellular respiration is a vital process that occurs in the cells of all [[plants and some bacteria ]].
A current of water is maintained through the gills for gas exchange, and food particles are filtered out at the same time. These may be trapped in mucus and moved to the mouth by the beating of cilia. [16] Respiration in the echinoderms (such as starfish and sea urchins) is carried out using a very primitive version of gills called papulae.
The concentration of oxygen in water is lower than air and it diffuses more slowly. In a litre of freshwater the oxygen content is 8 cm 3 per litre compared to 210 in the same volume of air. [7] Water is 777 times more dense than air and is 100 times more viscous. [7] Oxygen has a diffusion rate in air 10,000 times greater than in water. [7]
Artificial respiration, the act of simulating respiration, which provides for the overall exchange of gases in the body by pulmonary ventilation, external respiration and internal respiration Cheyne–Stokes respiration , an abnormal pattern of breathing characterized by progressively deeper and sometimes faster breathing, followed by a gradual ...