When they are given by inhalation or by the mouth their first effect is to produce marked dilatation of the small arteries, with a fall of blood-pressure and a greatly increased rapidity of the heart's action.
The terminal branches of the arteries supplying these organs are usually described as not anastomosing but many, if not all, of Cohnheim's end-arteries have minute collateral channels; which, however, are usually insufficient to completely compensate for the blocking that may occur in these arteries, therefore, when one of them is obstructed, the area irrigated by it dies from malnutrition.
Gull and Sutton asserted that in particular states of body, and more especially in the condition associated with cirrhotic kidney, such a fibrosis becomes general, running, as they alleged it does, along the adventitia of arteries and spreading to their capillaries.
The aortic trunk is very short, sends off the coronary arteries and then the left aorta brachiocephalica, while the rest divides into the right brachiocephalic and the aorta descendens.
The vascular system is not extensive, the arteries soon ending in the well-marked spongy tissue which builds up the muscular foot, parapodia, and dorsal body-wall.
A very remarkable feature in Limulus, first described by Owen, is the close accompaniment of the prosomatic nerve centres and nerves by arteries, so close indeed that the great ganglion mass and its out-running nerves are actually sunk in or invested by ch.
It seems that there is a primitive tendency in the Arthropoda for the arteries to accompany the nerve cords, and a " supra-spinal " artery - that is to say, an artery in close relation to the ventral nerve cords--has been described in several cases.
On the other hand, in many Arthropods, especially those which possess tracheae, the arteries do not have a long course, but soon open into wide blood sinuses.
Ce, Cerebral arteries; sp, supra - spinal or medullary artery; c, caudal artery; 1, lateral anastomotic artery of Limulus.
The figure B also shows the peculiar neural investiture formed by the cerebral arteries in Limulus and the derivation from this of the arteries to the limbs, III, IV, VI, whereas in Scorpio the latter have a separate origin from the anterior aorta.
The main arteries of the city are the Zeil, a broad street running from the Friedberger Anlage to the Rossmarkt and thence continued, by the Kaiserstrasse, through the fine new quarter built after 1872, to the magnificent principal railway station; and the Steinweg and Goethestrasse, which lead by the Bockenheimer Tor to the Bockenheimer Landstrasse, a broad boulevard intersecting the fashionable residential suburb to the N.W.
The Rhine, so long the home of romance, has become one of the great arteries of traffic, and lines of railways on both sides have caused small villages to become large towns.
The motor nerves of the arteries, of the bladder and rectal sphincters, and also of the bronchi, are paralysed by atropine, but the nervous arrangements of those organs are highly complex and until they are further unravelled by physiologists, pharmacology will be unable to give much information which might be of great value in the employment of atropine.
The rivers play a very important part in the economy of Borneo, both as highways and as lines along which run the main arteries of population.
Vital spirit, inhaled from the outside air, rushes through the arteries till it reaches the various centres, especially the brain and the heart, and there causes thought and organic movement.
As main arteries for this circulation of water through its system great canals, constituting in reality so many branches of the river, connected all parts of Babylonia, and formed a natural means both of defence and also of transportation from one part of the country to another.
The feeling of heat is at first an internal one, but it spreads outwards to the surface and to the extremities; the skin becomes warm and red, but remains dry; the pulse becomes softer and more full, but still quick; and the throbbings occur in exposed arteries, such as the temporal.
These soluble salts combine with the albumins in the body, and are deposited as minute granules of silver albuminate in the connective tissue of the skin papillae, serous membranes, the intima of arteries and the kidney.
With changes of the pressures of the blood in arteries, veins or capillaries, and in the heart itself and its respective chambers, static changes are apt to follow in these parts; such as degeneration of the coats of the arteries, due either to the silent tooth of time, to persistent high blood pressures, or to the action of poisons such as lead or syphilis.
His knowledge of anatomy, physiology and pathology was necessarily defective, the respect in which the dead body was held by the Greeks precluding him from practising dissection; thus we find him writing of the tissues without distinguishing between the various textures of the body, confusing arteries, veins and nerves, and speaking vaguely of the muscles as " flesh."
In Anodonta the blood is driven by the ventricle through the arteries into vessel-like spaces.
The other drainage arteries are all small, but many in number; while lakes and marshes aggregate fully 222% of the total surface.
Nitrite of amyl has the power of dilating the arteries; it has consequently been employed with much success in lowering the blood pressure and removing the pain in angina pectoris.
But if such a remedy were given alone it might, and probably would, act on the arteries as well as the heart, and by causing the contraction of the vessels do more harm than good.
By raising the hand nearly to a level with the head both the constant pain and the severity of the throbs may be relieved, as the blood is not sent with such great force into the arteries and returns more readily through the veins.
The reason probably is that the application of cold causes contraction of the arteries leading to the inflamed part, while heat by dilating the vessels around forms a side channel through which the blood passes, the tension in the seat of inflammation being thus lessened in both cases.
Blisters applied at some distance from inflamed parts are also sometimes useful; and probably they produce this good effect by causing a reflex contraction of the arteries in the inflamed part, and thus acting like a cold application.
High tension in the arteries is often associated with sleeplessness, the pressure of blood being such that the circulation in the brain is constantly maintained at a high rate of speed and the brain is unable to obtain rest.
The Hab river, which forms the boundary west of Karachi; the Purali (the ancient Arabus), which drains the low-lying flats of Las Bela; the Hingol (the ancient Tomerus) and the Dasht, which drain Makran, are all considerable streams, draining into the Arabian Sea and forming important arteries in the network of internal communication.
Directly south are the beginnings of the meridional arteries, the Hab, the Purali and the Hingol, which end in the Arabian Sea, leaving a space of mountainous seaboard (Makran) south of the Panjgur and west of the Hingol, which is watered (so far as it is watered at all) by the long lateral Kej river and several smaller mountain streams. Thus southern Baluchistan comprises four hydrographical sections.
Such are the Takazze in the north, the Abai in the centre, and the Sobat in the south, and through these three arteries is discharged about four-fifths of the entire drainage.
Traces of former rivers and channels, which were the main arteries of prosperous regions within the period of written history, have now disappeared.
BASSEIN, the chief town and port, is the capital of the district and division, and is situated on the eastern bank of the Bassein river, one of the main arteries by which the waters of the Irrawaddy discharge themselves into the sea.
The main roads laid out as arteries of intercommunication by the Romans, suffered to fall into neglect, and revived in the coaching days of the beginning of the 19th century, fell into a second period of comparative neglect when the railway system was completed; but they have recovered a very large share of their old importance in consequence of the development of motortraffic. Following the Roman roads, the high roads of the Eastern Division very frequently run along the crests of ridges or escarpments; but in the Western Division they are, as a rule, forced by the more commanding relief of the country to keep to the river valleys and cross the rougher districts through the dales and passes.
- In England and Wales the high-roads, or roads on which wheeled vehicles can travel, are of two classes: (I) the main roads, or great arteries along which the main vehicular traffic of the country passes; and (2) ordinary highways, which are by-roads serving only local areas.
In the time of Alexander the Great Praxagoras discovered the distinction between the arteries and the veins.
It has been found that in many cases of this disease the pressure of blood within the arteries becomes increased, probably from spasmodic contraction of the arteries themselves.
Its first action on any of the body-tissues is upon unstriped muscle, so that the first consequence of its absorption is a contraction of the arteries and arterioles.
Physostigmine, indeed, stimulates nearly all the non-striped muscles in the body, and this action upon the muscular coats of the arteries, and especially of the arterioles, causes a great rise in blood-pressure shortly after its absorption, which is very rapid.
It consists of arteries, veins and sinuses, but ramified capillaries are usually absent except in the integuments of Cephalopods.
The arteries and veins have proper endothelial walls; they pass abruptly into the sinuses and in some cases communication is effected by orifices in the walls of the vessels, as for example in the vena cava of Nautilus.
The ramifications of the arteries convey the blood to all parts of the body, and it finally reaches the venous sinuses, the chief of which are the pedal, the pallial and the median-ventral.