Licence: Public Domain Mark
Credit: Surgery. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![the injured part will he scl-h to almost ininiecliatL-ly dilate, an increased current of blood will be seen to at once flow to the [)artand ra[)idly traverse its vessels. Or, if a grain of dust becomes lodged in the eye, vessels will be seen shooting over parts which were previously j)erfectly white, denoting an increased afflux of blood to the part. The dilatation of the blood- vessels appears to be caused in one of two different ways: either as a reflex act due to irritation of the sensory nerves supplying the part, in which case it may be either a normal or a diseased action ; or, secondly, by acting injuriously on the arteries and paralysing their muscular coats, in which case the condition is an abnormal one, and is, indeed, the first stage of inflam- mation.' The manner in which determination is set up as a reflex action is believed to be as follows : the muscular coats of the arteries are supplied by symi)alhetic nerves, and it is proved by experiment that when the sensory nerve supplying a given area is irritated, a condition of inhibition is set up, by reflex action, in the sympathetic vasomotor fibres of the vessels supplying the area. As a result of this inhibition the tonic contraction of the muscular coat is lost and the vessels become dilated, with the natural result that an increased quantity of blood finds its way into them and there is a condition of active congestion. ^Vhen, however, the irritant applied is sufficiently powerful to injuriously affect the coats of the vessels, the muscle cells of the middle coat become paralysed, and as a natural consequence the vessels become dilated and active congestion is set up as a morbid process, forming, as we shall hereafter see, the first phenomenon in the ])ro(ess of inflammation. Symptoms.—The symptoms of active congestion are those which we should expect to find in a part in which there is an increased quantitv of blood flowing with increased rapidity, and therefore parting with less oxygen, and consequently being of a brighter colour than natural, (i) In consequence of there being an increased quantity of blood in the part there is a certain but variable amount of swelling and a sensation of fulness. (2) Flowing with increased rapidity, the blood has time to part with but little of its oxygen to the tissues in its passage through the capillaries, so that that portion of it which is finding its way into the radicles of the veins, carrying the blood away from the congested area, is still to a considerable extent arterial, and this gives to the part, if it is on the .surface of the body, a bright scarlet hue. (3) In consequence of the increased quantity of blood in the part there is an increase in its temperature, appreciable not only to the patient's sensations, but also to the hand of the surgeon. So far it will be seen that the symptoms of active congestion, are almost identically the same as those which were stated above as being the cardinal signs of inflammation, viz. modification of sensation—scarcely amounting, it is true, to pain —heat, redness, and swelling ; but there is, in addition to these, another symptom-increased functional activity of the part—which is always found where the active congestion occurs as a physiological condition, in which there is an important difference from inflammation, where the functional activity is either perverted or diminished or, it may be, abolished. Effects.—The effects of active congestion may be stated to be nil, as regards any evil consequences, so long as it is not long continued or fre- quently repeated. If this be so it may give rise to permanent dilatation of the capillaries and hypertrophy of the tissues comprised in the con- gested area. ' See page 7.](https://iiif.wellcomecollection.org/image/b21210846_0029.jp2/full/800%2C/0/default.jpg)
