Brain

See also: Brain (homonymy)

In Anatomy Animal E and human E, the brain (or Prosencéphale ) is the central Organe supervising the Nervous system. Although the brain is readily quoted like centers supervision of the central Nervous system of the Vertébré S, the same term can be employed for the central nervous system of the Invertébré S.

To note that in the language running, the term “brain” is employed to indicate the whole of the Encéphale, i.e. the part of the central nervous system located in the cranial box , which includes for example, the Cervelet. The brain is also called vulgarly brain .

Overall picture

The brain of the Vertébré S controls and coordinates the majority of the movements, of the Comportement, the Homéostasie of the internal functions, such as the Cardiac rhythm, the blood Pressure and the Température of the body.

The brain presents a functional organization: certain parts of the brain manage more specifically certain aspects of the behavior or the thought. But this functional division is not strict, it would be indeed illusory to assign a function as complex as the memory, for example, with an isolated region. One can nevertheless draw a cartography of the brain in cerebral surfaces according to their role in the Cognition: the driving functions in the frontal Lobe, the Vision in the posterior part of the occipital Lobe, the language articulated in the frontal Lobe on the level of the Surface of Broca, etc At the majority of the Vertebrate S, the brain is in the cranial box , where it is protected by the Os from cranium, like by the Liquide céphalo-spinal. It is a even Organe consisted of two hemispheres connected between them by fibers of white Substance via the callous Corps and the Commissure S.

At the stage Embryo naire, the brain of vertebrate develops starting from the Neuroderme, itself resulting from the Ectoderme (which will give also the Peau).

See also: Neurodéveloppement

Comparison and evolution

The Ver S Nématode S do not have more few hundreds of Neuron S in all their nervous system, when the human being has them approximately 20 billion in the Néocortex. Among the Mammalian S, Homo sapiens is one of the animals whose relationship between the mass of the brain and the body mass is highest (report/ratio masses cerebral/body mass of 1/46-48 for the man, but of 1/31 for the mouse for example). Other animals have a larger brain, like the dolphin or the elephant. From the point of view of the Phylogenetic evolution , the human brain underwent an important cortical expansion. But this expansion was not homogeneous: certain areas increased more cuts some than others, it is for example the case of the Cortex préfrontal.

Anatomy

The brain is coarsely divided into three parts: the posterior pit, where one finds the lengthened Moelle and the Métencéphale (left most antiquated which manages the essential functions: Cardiac rhythm, Breathing, temperature interns…) ; the “average” brain (Mésencéphale); and the “former” brain (Prosencéphale: Diencephalon and Télencéphale).

The human brain has a Cervelet, connected in parallel on the cerebral Tronc, with the posterior face of this one.

The nervous system of the Vertébré S is characterized by the Encéphalisation and symmetry from the hemispheres.

The animals more advanced developed a complex organization, in layer and network, their cells.

The human brain is composed of two hemispheres connected by the callous Corps (nervous fiber bridge, therefore of white Substance)

In addition, the convolutions appear, and make it possible to increase the surface of the gray Substance in periphery of the brain. This substance is consisted of the cellular body of the neurons, i.e. where are received, processed and integrated the electric data, before emitting an answer. The white Substance, it, is made up of nervous fibers: i.e. made up of Axon S of neurons, which move towards their destination in the brain, or the remainder of the body.

Example: the pyramidal Faisceau is composed of the fibers which will order the Muscle S and will allow the voluntary Motricité. This beam is originating in the cortical gray substance of the frontal areas of the brain (left former the brain), then it walks on in the brain, the cerebral trunk, the spinal-cord, where it regularly gives nerves made up of some of its fibers, towards the muscles of the body.

One finds also substance gray in Cores gray central, which is small formations coarsely ovoid, which are with deepest brain and which manages certain vital functions, as well as the memory.

The Méninges are the fabric envelopes which are between osseous cranium and the brain. They are made up of the Dure-mère (all against the Crâne), of the Arachnoïde, and the Pie-mère (which papers the brain very closely).

Functions

The brain of vertebrate receives signals by the related nerves (i.e. their information “goes up” towards the brain. It is the case of the sensory nerves, which convey the Sensation S, for example the pain: Skin with the brain) on behalf of each portion of the body; it receives this signal, the interpreter, and an answer based on integration draws some from the received electrical signals, then transmits it.

This set of receptions and emission of signals (after their integration) represents the major function of the brain, which explains at the same time the feelings, the movement, the memory… and also the Conscience.

The higher cognitive activities (intelligence, the reflection) proceed in the former parts of the brain: frontal lobes (right and left), particularly by their interactions with the limbic system (thalamus, hippocampus brain), which belong to the gray cores.

The brain has also a role of hormonal production, starting from the Hypophyse, of the Hypothalamus, the épiphyse in particular (three small areas located at the base of the brain implied in the management of the other hormones)

Thus, by the central role which he exerts in the collecting of the external stimuli, the brain occupies the central role of creation of the reactions to the environment. Hunger, fear, danger, pain, need to urinate, etc are stimulations the final goal is in zones specialized of the brain, which analyzes the Information there, before answering by the appropriate response.

On the other hand, one should not mistake to think that the brain is responsible for the movements reflexes, such as for example the fact of removing our hand immediately when it comes into contact with an extreme surface. It is spinal-cord, and not brain, which these movements reflexes come.

See too

brain|brain

Related articles

External bonds

  • the brain on all the levels
  • See a diagram detailed on the brain (sagittal cut)
  • the three brains, medical Encyclopedia Vulgaris
  • the brain Its operation, its development, its diseases and analysis of our behaviors in this body.

; Animations

  • Presentation of the various lobes of the brain and their respective roles (animation flash)
  • cerebral surfaces specialized and their specific functions (animation flash)
  • Various interactive anatomical atlases and vidéos
  • the language and the brain on the site of the neurologist Jean Métellus
  • the operation of the brain

Simple: Brain

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