That this action is a direct and not a nervous one is shown by the fact that if the eye be suddenly shaded the pupil will dilate a little, showing that the nerves which cause dilatation are still competent after the administration of physostigmine.
When this gland becomes enlarged, and its secretion consequently increases, the vessels dilate, the heart beats more rapidly, the skin becomes too hot, the nervous system becomes irritable, and tremors occur in the limbs.
The Veda, it is true, does not usually dilate much on the worst of these adventures.
Small doses of any of them dilate the blood vessels from an action on the vaso-motor centre in the medulla oblongata, as a result of which the heart beats more rapidly and the blood circulates more freely; but larger doses have a general depressing effect upon the circulatory system.
Drugs acting on the blood vessels, which either dilate the vessels when taken internally or applied locally, or contract the superficial arterioles.
Internally: Dilate solutions of potash, like other alkalis, are used to neutralize the poisonous effects of strong acids.
Externally chloroforrr ‘ is an antiseptic, a local anaesthetic if allowed to evaporate, and a rubefacient, causing the vessels of the skin to dilate, if rubbed in.
But whilst the characteristic action of atropine is to dilate the blood-vessels, its first action is to stimulate the vaso-motor centre - thereby causing temporary contraction of the vessels - and to increase the rapidity of the heart's action, so that the blood-pressure rapidly rises.
Atropine is universally and constantly used in ophthalmic practice in order to dilate the pupil for examination of the retina by the ophthalmoscope, or in cases where the inflamed iris threatens to form adhesions to neighbouring parts.
Symptoms attendant on the hypnotic state are closure of the eyelids by the hypnotizer without subsequent attempt to open them by the hypnotized subject; the pupils, instead of being constricted, as for near vision, dilate, and there sets in a condition superficially resembling sleep. But in natural sleep the action of all parts of the nervous system is subdued, whereas in the hypnotic the reactions of the lower, and some even of the higher, parts are exalted.
They therefore lessen all the secretions, and among other actions dilate the pupil and increase the rapidity of the heart by paralysing the vagus.
Taking up a piece, he would request his visitor not to breathe upon it, nor handle it; he would dilate upon the many merits of the drug and the cures it had effected.
Loch Dilate lies 11 m.