AC, Arterial canal or foramen.
It is not surprising that with so highly developed an arterial system Limulus and Scorpio should have a highly developed mechanism for determining the flow of blood to the respiratory organs.
The chief varieties of haemorrhage are arterial, venous and capillary.
The heart has a pair of venous ostia, often blending into one, and an anterior arterial aorta.
The right and left halves are completely divided by septa, no mixture of the venous and arterial blood being possible, an advance upon reptilian conditions, even the highest.
Mackay, " The Development of the Branchial Arterial Arches in Birds, with special reference to the Origin of the Subclavians and Carotids," Phil.
If the flow of arterial blood only is arrested, the part depending upon it for nutrition becomes numb, cold and shrivelled, and the form of mortification known as dry gangrene occurs.
- Diagram of the arterial system of A, Scorpio, and B, Limulus.
They supposed that it was accompanied by a peculiar hyaline thickening of the arterial wall, usually of the tunica intima, and hence they termed the supposed diseased state " arterio-capillary fibrosis," and gave the fibrous substance the name " hyaline-fibroid."
And it is not alien from the present point of view to turn for a moment to the light thrown on the cardio-arterial pulse and the measurement of its motions by the more intimate researches into the phenomena of the circulation by many observers, among whom in the 19th century James Hope, E.
Such injuries are apt to occur in syphilitic endarteritis, or senile arterial decay, whereby an artery may be blocked permanently, as if with an embolus, and the area supplied by it, in so far as it was dependent upon this vessel, deprived of nutrition.
In the sphere of physiology and in the interpretation of associated arterial diseases much obscurity still remains; as, for instance, concerning the nature of the toxic substances which produce those bilateral changes in the kidneys which we call Bright's disease, and bring about the "uraemia" which is characteristic of it.
And on the influence of these inconspicuous bodies and of the pituitary body in sustaining arterial blood pressures physiologists have thrown some important light.
Marey, 1863) attention was drawn to the physical features of the circulation, to the signs of degeneration of the arterial tree, and less definitely to the fluctuations of blood pressure; but as we have said under the consideration of diseases of the heart, the kymographs of Ludwig and his pupils brought out these fluctuations far more accurately and completely.
The valley of the Brahmaputra (q.v.), or Yaru Tsang-po or simply Tsang-po - the river has also various local names - is the great arterial valley of southern Tibet.
The respiratory rhythm is less frequent and the breathing less deep; the heart-beat is less frequent; the secretions are less copious; the pupil is narrow; in the brain there exists arterial anaemia with venous congestion, so that the blood-flow there is less than in the waking state.
This may occur suddenly, as when the resistance is increased in the arterial system by a e on f sudden exertion or strain, and more slowly when the resistance is increased in the pulmonary circulation of the by inflammation of the respiratory passages.
3 and 4, snp), and further a dorsal gastric canal and arterial canal which transmit the alimentary tract and the dorsal artery respectively (figs.
In Scorpio the completion of the horizontal plate by oblique flaps, so as to form an actual diaphragm shutting off the cavity of the prosoma from the rest of the body, possibly gives to the organs contained in the anterior chamber a physiological advantage in respect of the supply of arterial blood and its separation from the venous blood of the mesosoma.
The arterial system is very completely developed in both Limulus and Scorpio, branching repeatedly until minute arterioles are formed, not to be distinguished from true capillaries; FIG.
The connexion is not so intimate in Scorpio, but is nevertheless a very close one, closer than we find in any other Arthropods in which the arterial system is well developed, e.g.
Scorpio certainly comes nearer to Limulus in the high development of its arterial system, and the intimate relation of the anterior aorta and its branches to the nerve centres and great nerves, than does any other Arthropod.
Nitroglycerin is valuable as a preventive in cases of cardiac pain, such as angina pectoris, and it is also used in other conditions where it is desirable to reduce the arterial tension.