How does an organism exist and develop? We commonly speak of the number of calories in different types of food products. The main idea seems to be that the more calories we consume, the more weight we gain. Simple Western dietary systems are based on the calculation and restriction of calories. However, after initial enthusiasm for this system and after thousands of pages published on the subject it was discovered that in most cases it simply did not work. An individual organism is much more complicated than an oven, where you can calculate heat produced from the fuel loaded. Some people can eat quite sparingly and stay active and healthy; some need a lot of food all the time. Many families suffer from the permanent hunger of growing children.

 On the other hand, we need to ask the question: do we produce physical energy only from food? If this was the case, then how could little birds fly across the Atlantic? Let us make a simple calculation. A direct measurement of energy expenditure for free-flying songbirds migrating from Panama to Canada by using doubly labeled water was reported by a big international group [1]. In accordance with their measurements migratory flight used 15.5 kJ* h-1 total energy while flying, which agrees with predicted values estimated from multiple models and wind-tunnel studies [2,3]. For songbirds, one nocturnal non-stop flight for up to 600 km lasts about 7.7 h, which takes 119.35 kJ of energy. At the same time researchers found by direct measurements that individual birds had roughly the same body weight and fat content in the mornings before and after their migratory flights (6% body-weight loss), no change in fat content [1]. For 30 g bird, 6% is 1.8 g. Each gram of carbohydrate provides four kcal of energy (16.75 kJ), one gram of fat provides nine kcal (37.68 kJ) [4]. Direct transformation of 1.8 g of body mass to energy provides from 30 to 68 kJ of energy. In reality only part of weight loss generates energy, so this number would be even less. As we see, from 119 kJ spent less than half would be covered by body mass. For birds flying through Atlantics for 3000-4000 miles non-stop, these calculations demonstrate that they should have lost more than half of their weight during flight, which they do not. So the typical belief that “a few grams of fat can be enough to fuel a hummingbird or a warbler for a thousand miles over the Gulf and beyond” is wrong. Birds need fat to protect their body from the low temperatures and winds, which they meet at high altitudes, but this fat is not enough to fuel their flight. From the classical point of view it is impossible for the little birds to fly across the ocean, but they do and have been doing so for thousands of years! Technically and scientifically speaking, they should fall into the sea halfway across and be drowned but they do not. Do they follow another set of physical laws than those affecting inanimate objects?
We believe that there is one and the only Physics: The Physics of the Material World that is valid both for inanimate subjects and living beings. The only difference consists in the complexity and time-span of the processes. When a stone accepts sun energy, its temperature increases: the more sun, the higher the temperature. To some extent, a stone may be accepted as a CLOSED SYSTEM. When a healthy person stays in the sun, his temperature remains constant and we can assume that a person maintains HOMEOSTASIS – that is equilibrium, or balance with the surrounding environment. This is only possible due to the two-sided process of interchange. We accept energy from the sun, from food, from the air, and we dissipate energy in space. Schrödinger and later, Prigogine, Haken and others developed the concept that biological subjects are so-called OPEN SYSTEMS. It means that all during the lifetime they exchange not only material stuff, but both energy and information with the environment.
How this may help a bird in a migratory flight to generate an extra energy?
We do not believe that cells work as a “nuclear reactor,” but we assume that birds may extract energy directly from the air. Birds breathe using a unique system in which air follows a one-way route through the respiratory system. This system is unlike our lungs, in which the air backtracks where it came from. Their system of respiration (breathing) is very efficient - much more efficient than our system. Birds have two relatively small lungs (where gas exchange occurs), but the lungs are augmented by bellows-like air sacs (where no gas exchange occurs). These air sacs keep the lungs perpetually inflated (even when the bird is exhaling). Our lungs alternately fill and empty out. The bird's respiratory system takes up 20% of a bird’s volume (our respiratory system takes up only 5% of our volume). In the bird's respiratory system, air first flows through air sacs (located even inside their hollow bones) that direct fresh, oxygenated air into the tube-like lungs (parabronchi, where gas exchange occurs) both when the bird inhales and when it exhales [3]. We assume that together with molecular oxidation there should exist some alternative way of O2 utilization, which provides metabolic energy.
Oxygen molecule (O2) is unique among other molecules in the environment. It has two electrons with parallel spins (unpaired electrons) on its valence molecular orbital (M↑↑, where ↑ represents an electron with a certain spin) [5]. Such constitution of an outer electron shell is termed a triplet state. Triplet О2 is a vast energy store, able to release more than 180 kcal/mole upon its reduction to two water molecules after gaining four electrons (together with their carriers – protons). However, it cannot be spontaneously reduced, because according to Wigner spin conservation rules it cannot directly interact with singlet state molecules [6], and that is one of the reasons of triplet oxygen stability. There are several ways to activate oxygen, and one of them – one-electron oxygen reduction. When electrons are taken by О2 one after another, intermediate products – reactive oxygen species (ROS) arise. Some of them are free radicals: chemical species, which unlike usual molecules possess an odd number of electrons at their valence electron shell. In the desire to get a pair for a lone electron free radicals avidly interact with the neighboring electron donors, which are normally represented by molecules. A free radical gains an electron from a molecule and turns into a molecule, while a molecule turns into a free radical and starts to look for another electron donor. Thus, free radicals may initiate chain reactions in solutions containing bioorganic molecules such as lipids, proteins, nucleic acids, carbohydrates. The best solution of this kind is blood [7].

Can a bird fly across the Atlantics? (*.doc)