An Introduction to Physiology

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The University Press, 1901 - Electronic books - 314 pages
 

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Page 14 - As a unit of resistance, the international Ohm. which is based upon the ohm equal to 109 units of resistance of the CGS system of electro-magnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grammes in mass, of a constant cross-sectional area, and of a length of 106.3 centimetres.
Page 14 - As a unit of electromotive force, the international volt, which is the electromotive force that, steadily applied to a conductor whose resistance is one international ohm, will produce a current of one international ampere...
Page 14 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 246 - ... between the pump and the principal resistance. (4) The membrane manometer shows a sudden rise and fall indicating a sudden rise and fall in the intraventricular pressure. (5) Close observation shows that on the stroke of the pump the tubing just distal to the aortic valve begins to expand sooner than that farther away. Evidently the change of pressure produced by the stroke of the pump is transmitted from point to point through the liquid in the tubes. (6) The arterial manometer shows a sudden...
Page 246 - Open the side branch near the capillaries by unscrewing' the pressure clip. See that the tubes are well filled with water. Make a single brief, gentle pressure on the bulb. Note (1) that practically all the liquid driven out by the stroke escapes through the side branch, in which the resistance is low, rather than through the high capillary resistance. (2) Only a portion of t"he liquid escapes during the stroke. (3) The portion which cannot escape by the resistance during the stroke finds space in...
Page 250 - The mercuryremains at a mean level broken by a slight accession at each stroke. The pump now merely maintains the constant high arterial pressure. This pressure suffices to drive through the resistance during each stroke and the succeeding interval all the liquid received from the pump during fhe stroke.
Page 248 - ... interval between the strokes is shortened the liquid received from the pump in any one stroke cannot all escape past the resistance during the stroke and the succeeding interval. The stream becomes remittent. Note that the arterial pressure remains low even after the stream becomes continuous. (c) Close the side branch, so that the liquid must pass through a high peripheral resistance. Compress the bulb at such a rate that the outflow shall be continuous. The frequency required to make the flow...
Page 246 - This interval is occupied by the transmission of the pressure change from the pump to the mercury column, and in part by the time required to overcome the inertia of position of the mercury. The oscillations of the. mercury following the primary rise and fall are due to inertia. (7) Observe the action of the valves...
Page 247 - ... following the fall are due to inertia. (7) Observe the action of the valves. (8) Place a finger on the aorta and note the pressure wave pulse as it passes along the vessel. 6. With the side branch open as in experiment 1, compress the bulb rhythmically and gradually increase the frequency of the strokes. It will be found that at about twenty strokes to the minute the stream will be intermittent. As the interval between the strokes is shortened the liquid received from the pump in any one stroke...
Page 27 - The oxidation of a side-chain by means of permanganate solution is one which is commonly employed where the acid is required. The monohalogen derivatives are readily oxidised in this way, but greater difficulty is experienced if two halogen...

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