The ability of living organisms to respond to external influences is an innate property and protective reaction

The ability of living organisms to respond to external influences is one of its most important properties with which it comes into being. What does this ability mean for all living things? Let's find out more.

The concept of "irritability"

From the point of view of physiology, any reaction of the organism to the influence of the environment is considered irritability. Because the conditions of existence are constantly changing, its inhabitants must be able to adapt to them in order to survive. It is an innate property of the nervous system. Although representatives of wildlife that do not have it, they also react very actively to external influences.

Plant Taxis

The ability of living organisms to respond to external influences is also characteristic of plants. And this despite the fact that they do not have a nervous system. Try to touch the leaves of the mimosa bush - literally before your eyes they will begin to form in response to mechanical irritation. This is a manifestation of irritability in the form of motor reactions - taxis. Naturally, plants do not overcome significant distances. Their movements are rostovye and arise in response to a number of factors. They can be lighting, gravity, pressure or chemical compounds. Check the existence of taxis is very simple. To do this, simply rotate the houseplant from the light, and after a while its leaf blades will again settle in its direction.

Instincts and reflexes of animals

But the ability of living organisms to respond to external influences in multicellular animals is due to the presence of the nervous system. It consists of specialized cells, which are called neurons. In them, as a result of external action, electrical impulses arise. On the processes they are transferred to the centers of the brain, where they are analyzed. After that, the signals are transferred back to the working bodies. This process is almost instantaneous. Such responses of animal organisms to stimulation are called reflexes. They can be of two kinds.

Congenital provide the vital functions of the body from the moment of its appearance. It is respiratory, sucking, grasping, blinking, protective reflexes. Some reactions are formed in animals only during life. These are acquired reflexes. For example, a dog can be trained to perform an action after a certain command. Many animals have a system of complex behavioral reactions - instinct. This is marital behavior, caring for the offspring, bird migration, migration, construction of honeycombs by insects, etc.

Single-celled animals are also able to respond to changing environmental conditions. This happens in the form of taxis, as in plants. If a drop of salty and fresh water is applied to the slide on which the infusorians are located, the protozoan will start moving towards the second. Movement can be carried out both from a source of irritation, and to it. For example, the unicellular alga of chlamydomonas moves towards the source of sunlight. This provides better conditions for the process of photosynthesis.

Reaction to external influences: value for living organisms

First of all, the ability of all living organisms to respond in some way to the effects of the environment is of protective importance. In animals, nervous regulation is very fast. Due to this they immediately react to various stimuli. Along with the nervous for animals, the humoral regulation of functions is also characteristic. It is carried out with the help of endocrine glands. Its effect is much slower. For example, the pituitary gland secretes growth hormone for many years, during which quantitative changes in the body gradually occur. In its totality, the nervous and humoral regulation represents a coherent and perfect system of work and irritability of organisms.

So, the response of all living things to stimuli provides the conditions for their existence, protection and the basis of adaptation. The ability of living organisms to respond to external influences manifests itself in the form of taxis and reflexes.