Presence Or Absence Of Food, Physical Conditions Of

Presence or absence of food, physical conditions of environment, degree of its pollution - here those primary factors, with which inseparably linked organism ability to live. At the same time any organism can exist, only if the structure of its body is supported in certain, usually enough narrow limits. Great French physiologist Claude Bernard has formulated more 100 years ago this position as follows: the constancy of the internal environment is a necessary condition of a free life of an organism. The law of a constancy of the internal environment of an organism - the fundamental law of biology. I even would designate it as the First fundamental biological law (though in this case a little that speaks a serial number: all fundamental laws are characterised by that any of them cannot be broken). The metabolism based on receipt in an organism of food, water and oxygen, first of all provides a constancy of the internal environment. At monocelled beings reserves of power materials in an organism are very insignificant and according to their dependence on food receipt, as a rule, is extremely expressed.

In Space, Or A Crack ( A Crack),

In space, or a crack ( a crack), between nervous cages from a shoot are allocated substances-intermediaries which, like hormones, operate on receptors of a membrane of the next nervous cage, stimulating or, on the contrary, braking its activity. And everyone a cage, besides, has on the membrane receptors-aerials for an attachment of working hormones glands. These hormones operate on on a feedback mechanism, stimulating or braking activity cages. Each of three basic systems has in the representations - kernels, or the centres, and even a number of the interconnected centres. In cages of these centres are made special hormones which supervise production of each hormone of a forward share of a hypophysis. In turn, on the nervous cages forming these centres, have an effect, as hormones, and hormones peripheral glands, that is working hormones. The structure provides ample opportunities for change of a threshold of sensitivity of this regulator. Really, most simple way of change of a threshold of sensitivity to action of working hormones is change of number of aerials-receptors on a membrane of cages corresponding the centre, for example "the sexual centre" reproductive system.