PHYSIOLOGY OF PERSPIRATIONMECHANISMS OF CONTROL OF PERSPIRATION :
They are nervous and hormonal.
I) Nervous mechanisms:
They comprise the sweat nerves and the overlying nerve centres.
They stimulate perspiration directly.
a) The sweat nerves train a rich person network of fibres around gland. A part is intended for the secreting cells and the others innervent the driving cells. The system sympathetic nerve controls perspiration the glands can be stimulated by the agonists cholinergic and adrenergic a and
b.
b) Medullary and cerebral centers.
The principal center is in the hypothalamus. It sends fibers in the ventral roots of marrow which make relay in the ganglia sympathetic nerves para vertébraux.
The ganglionic fibers post use the corresponding spinaux nerves to be distributed to glands of sudation.
The D1 ganglia in D4 innervent glands  head and neck, D2 with D8 those of the upper limbs, D6 with D10 the trunk, D11 etD12 those of the lower limbs.
The related ways are stimulated by sensors sensitive to the central temperature and that of the skin.
The rate of sudation is also modulated by physical parameters in the immediate vicinity of glands. They are stimulated by an increase in temperature of 5° approximately. A fall of the local temperature of the skin, moisture or local blood flow decrease the activity of gland concerned. A lack of water inside the human body will decrease the total rate of sudation.
2) Hormonal mechanisms:
They have especially an action on the composition of the sweat.
They make it possible at the time of sudation to maintain a balance hydro electrolytic.
III) COMPOSITION OF SWEAT:
Sweat is a hypotonic solution salt works (99% of water) of which it is difficult to give an exact composition which is not an instantaneous stereotype so much this one can vary according to the seat, conditions of renewal, type of sweat stimulation and adaptation of the subject.
IV) STIMULI OF PERSPIRATION :
a) The thermal sweat answer:
It is initially related to the number of stimulated glands, then with an increase in the output of each one. This takes a certain latency time. Coarsely,
the trunk ensures 50% of thermal sudation, the lower limbs 25%, the remainder being ensured by the upper limbs and the head. Certain zones are particularly active for example: the face, the back and the former area medio thoracic. It is thus the trunk which takes part above all in the thermal sweat adaptation.
b) The psychic sweat answer:
This one appears only after one emotional stress which was worth the qualifier to him of "cold sweat".
This sudation is characterized by its central origin, its speed of appearance (less than 20 seconds) which seems related to the contraction of glands outside driving out sweat. Its topography is particular since it appears in zones, either almost exclusively cold like the palms and the plants, or in zones mixed like the face, the folds axillaires,
groin or poplitea; nevertheless in a raised ambient temperature, above 31°, it can be seen on all the surface of the body.
c) The gustatory sweat answer:
It occurs at many normal people after the pepper ingestion. This perspiration of the face which extends sometimes to the neck and the higher part of the trunk is dependent on a medullary arc reflex.
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