This article traces the trajectory of respiratory complexity from invertebrates to vertebrates and as organisms moved from the deep ocean onto land and into the sky. Gas exchangers arose as simple air-blood diffusion interfaces that in active animals progressively gained in complexity in coordination with the cardiovascular system, leading to serial “step-downs” of oxygen tension to maintain homeostasis between uptake distribution and cellular protection.Īll gas exchangers share basic features, for example, thin blood-gas barrier, large interface, ventilatory regulation, and low cost of breathing. The respiratory organ is the “gatekeeper” that determines the amount of oxygen available for distribution. Each system is adapted to deliver enough oxygen and eliminate enough carbon dioxide to allow the species to surmount specific environmental and predatory pressures while simultaneously limiting the energy cost of breathing and cumulative oxidative stress in cells and organelles within an acceptable range. Harnessing the energy from oxidative phosphorylation while minimizing cellular stress and damage is an eternal struggle transcending specific organ systems or species, a conflict that shaped an assortment of gas-exchange systems. While aerobic respiration is essential for efficient metabolic energy production, a prerequisite for complex organisms, cumulative cellular oxygen stress has also made senescence and death inevitable. Oxygen, a vital gas and a lethal toxin, represents a trade-off with which all organisms have had a conflicted relationship. Through the evolutionary directions and variety of gas exchangers, their shared features and individual compromises may be appreciated. We, therefore, survey the comparative anatomy and physiology of respiratory systems from invertebrates to vertebrates, water to air breathers, and terrestrial to aerial inhabitants. In an evolutionary context, certain species also become adapted to environmental conditions or habitual organismic demands. Within an organism's lifespan, the respiratory apparatus adapts in various ways to upregulate oxygen uptake in hypoxia and restrict uptake in hyperoxia. Here, we review the origin of oxygen homeostasis, a primal selection factor for all respiratory systems, which in turn function as gatekeepers of the cascade. Efficient respiratory gas exchange, coupled to downstream convective and diffusive resistances, comprise the “oxygen cascade”-step-down of PO 2 that balances supply against toxicity. Disparate systems exhibit similar directions of adaptation: toward larger diffusion interfaces, thinner barriers, finer dynamic regulation, and reduced cost of breathing. adult lungs) or simultaneous (e.g., skin, gills, and lungs in some salamanders). Habitat expansion compels the use of different gas exchangers, for example, skin, gills, tracheae, lungs, and their intermediate stages, that may coexist within the same species coexistence may be temporally disjunct (e.g., larval gills vs. Ambient oxygen tension ( PO 2) fluctuated through the ages in correlation with biodiversity and body size, enabling organisms to migrate from water to land and air and sometimes in the opposite direction. So before doing I wanted to be shure, that you dont have a clue or hint for me.Life originated in anoxia, but many organisms came to depend upon oxygen for survival, independently evolving diverse respiratory systems for acquiring oxygen from the environment. I thought of building a new Project B and step by step extend all the improvements - lots of work waiting. Removed service installation in Project B for test - no change. Many 100-thousand installations was sucessfully processed last 2 years. It was first build with IA6 or 7 I assume and "mirgrated" throught all IA versions. NET Dependencies for 32 and 64 bits referenced as web media blocks, german translation, rebranding, installing a windows service, running MS-Redistribution-Install if necessary, no install dir dialog when updating, detecting/terminating running executable before (un)installation, reduced dialog sequence, running pre-uninstall- and post-install administration executable, and so on. Our Project A has lots of custom adjustments: extended dialogs. B after A and A after B can be installed without error - as it should be. NET Project B installing only one different. Using "Product Code" of Project A in Project B will result in: "Previous version uninstallation" - (as expected).Ĭreating a simple.
0 Comments
Leave a Reply. |