Blood brain

Blood brain occurs through vertebrates and internal carotid arteries (Fig.). Vertebral arteries are connected at the rear edge of the bridge on the main artery.

the scheme of the arteries of the brain base The scheme of the arteries of the brain base:
1-front connection;
2 - the front of the brain;
3 - internal carotid;
4 - middle cerebral;
5 - front artery vascular plexus;
6 - rear connection;
7 - rear brain;
8 - superior cerebellar;
9 - main;
10 - the lifeline of the maze;
11 - front lower cerebellar;
12 - vertebral;
13 - back lower cerebellar;
14 - back and 15 - anterior spinal artery.

At the front edge of the bridge, the main artery divides into two posterior cerebral artery, connecting the rear connecting arteries with the internal carotid artery. From the latter depart middle cerebral artery. Anterior cerebral artery are connected anterior communicating artery. The ring formed by the arteries at the base of the brain, called blood (millisievert) range. The medulla and the bridge supplied by the branches of the anterior spinal cord and vertebral arteries, middle brain - branches of the posterior cerebral arteries. The latter also feeds the occipital lobe and the lower part of the temporal lobe of the brain. Anterior cerebral artery supplies the basal Department of the frontal lobe, and the medial surface of the frontal and parietal lobes and a large part of the corpus callosum. Middle cerebral artery runs on the base of the brain, in the area of the front perforatum space provides a number probcause branches getting into the substance of the brain and supplying subcortical nuclei. Then she falls in lateral sulcus and nourishes the outer surface of the hemisphere.
The venous system of the brain presents superficial veins that lie in the soft the meninges and the deep, bringing the blood of subcortical structures and ventricles in a large cerebral vein (Galen Vienna). All veins flow into the venous sinus Dura, from which the blood flows into the internal jugular vein. Along with this they have outflow in the system of external veins through the graduates.
The brain regulates the physiological processes in the body, controls the behavioral responses of human rights and carries out his mental activity. Regulation of vegetative processes carried out by keeping the body constancy of the internal environment (blood and osmotic pressure, blood sugar level, pH, body temperature , etc.,). The constancy of the internal environment of the body is supported on the principle of self-regulation, namely, that the deviation of one or another internal constants from normal level causes excitation in the brain certain entities that align these deviations. This process is carried out by different departments of a brain. In the medulla are such important centers as vasomotor, breathing. There are centers which simplest reaction: sucking, swallowing, chewing, vomiting, sneezing, coughing, blinking and other More complex vegetative processes are regulated by the upstream sections of the brain-the limbic system and hypothalamus (see Subcortical functions). In the hypothalamus, for example, are the centers of hunger and satiety, thermoregulation, sleep and wakefulness. In the structures of the limbic system are the centers of regulation of the sexual function of the body. Graduate regulation of vegetative processes carried out a bark of the big hemispheres, which is very thin fits for them to various activities of the body.
Human activities in the environment manifests itself in physical activity, which is carried out by reducing the various muscle groups. The brain subtly regulates these processes, ensuring adaptation of a person to any environmental conditions. Excitation caused by irritation from outside, enter the brain, are distributed in different subcortical structures, where they come into the bark of the big hemispheres. Bark they go in two ways. The first is projected by, the continuing through the nucleus of the thalamus to the flat areas of the cerebral cortex (visual, auditory, somatosensory). Damage to these areas leads to violation of the relevant functions (vision, hearing , etc.,) that speaks of localization of function in the brain (see Analyzers).
The second way of receipt of excitations in the cerebral cortex passes through the reticular formation of the middle brain. She sends ascending fluxes of excitement to all areas of the cerebral cortex, activating its cells and providing the waking state of the brain in General. The decrease in incoming brain stimuli decreases aguirutee impact of the reticular formation on the crust, which leads to the development of natural sleep. On the basis of the analysis and synthesis of a large number of irritants in the bark of the big hemispheres set the return motor reaction is carried out by motor area. Constant circulation of excitation between the cortex, thalamus, and other subcortical structures combines the brain into a single whole in the implementation of behavioral reactions. They are based on unconditional reflexes (see) and conditioned reflexes (see) and are always accompanied by emotional reactions (see Emotions).
The brain of a person performs mental activity, which consists in the subjective reflection of the objective world and in the formation in connection with this behavior. The leading role in the implementation of mental activity belongs to the cerebral cortex. Having great potential in the formation of many new temporary connections, it allows you to develop and maintain complex program behavior. Mental activity especially has been enriched by the development of human speech that resulted in his abstract thinking and allowed him to gain a dominant position in the animal world. It creates the basis for complex forms of conscious perception of the world and forms of higher mental functions (see Higher nervous activity).