Systemic circulation

P-Endorphin. A peptide corresponding to the 31 C-terminal amino acids of P-LPH was first discovered in camel pituitary tissue (10). This substance is P-endorphin, which exerts a potent analgesic effect by binding to cell surface receptors in the central nervous system. The sequence of P-endorphin is well conserved across species for the first 25 N-terminal amino acids. Opiates derived from plant sources, eg, heroin, morphine, opium, etc, exert their actions by interacting with the P-endorphin receptor. On a molar basis, this peptide has approximately five times the potency of morphine. Both P-endorphin and ACTH ate cosecreted from the pituitary gland. Whereas the physiologic importance of P-endorphin release into the systemic circulation is not certain, this molecule clearly has been shown to be an important neurotransmitter within the central nervous system. Endorphin has been invaluable as a research tool, but has not been clinically useful due to the avadabihty of plant-derived opiates. 

The bioavadabihty of a dmg can be defined as the fraction of a dose, L, that reaches the systemic circulation. When L < 1,... 

Fig. 3. Schematic representation showing the anatomical basis for differences in the quantitative supply of absorbed material to the Hver. By swallowing (oral route), the main fraction of the absorbed dose is transported direcdy to the Hver. FoUowing inhalation or dermal exposure, the material passes to the pulmonary circulation and thence to the systemic circulation, from which only a portion passes to the Hver. This discrepancy in the amount of absorbed material passing to the Hver may account for differences in toxicity of a material by inhalation and skin contact, compared with its toxicity by swallowing, if metaboHsm of the material in the Hver is significant in its detoxification or metaboHc activation.

Dmgs, such as opiates, may undergo metabolism both in the intestinal wall and in the fiver (first-pass metabolism). The metabolism may be extensive and considerably reduce the amount of dmg reaching the systemic circulation. Alternatively, the metabolite may be metabofically active and contribute significantly to the action of the parent dmg. Some compounds undergo enterohepatic circulation in which they are secreted into the GI tract in the bile and are subsequently reabsorbed. Enterohepatic circulation prolongs the half-life of a dmg. 

Steam-Generator Circulation System Circulation systems for utility application are generally classified as natural circulation and forced or pump-assisted circulation in drum-type boilers, and as once-through now in subcritical- and supercriticaf-pressure boilers. The... 

D = Cooling system duty, Btu/hr C = System circulation rate, GPM AT = Cooling system temperature difference (hot return water minus cold supply water), °F... 

The Loss of Heat Sink has three subclasses total loss of primary system circulation (5%), los,s of secondary cooling from effluent header failures (1 %), and total loss of secondary cooling from inlet... 

The eye has its own hydraulic system, and disturbances in it may cau.se serious damage to the eye. The normal eye pressure is 22 mm Hg, but when the pressure increases to 28-30 mm Hg, the optic nerve is squeezed and becomes hypoxic. This increase in the eye pressure may be due to acids or alkali causing inflammation in the anterior chamber of the eye, blocking the outflow of aqueous humor back into the systemic circulation. 

The frame lubrication system circulates oil to the frame bearings, connecting rod bearings, crosshead shoes, and can also supply oil to the packing and cylinder lubrication system. Splash lubrication systems are... 

Condenser Controls. .Miscellaneous (Condensing System). Circulating Water. System. Condensate Sysrem. . Pumpa, Piping and Valves. .Low/Tnter. Press- Heater/Oeaerators 3350-3352. .Polishers/Chemical Addle Ion 3360-3399. .Miscellaneous (Condensate System) 3901-3999. Feedwater System 3501-3509. Heater Drain Systems 3520-3529. Entractlon Steam. Electrical. Auxiliary Systems. .Service Water (Open System)... 

In Section 21.4 tlie effects of the release of toxic vapors were considered in connection witli an accident sequence initiated by the failure of a plant programmable automatic controller. In tliis study, event tree analysis and fault tree analysis led to identification of tlie glycol cooling system circulation pumps as components meriting high priority for inspection. 

Piping system Main steam Process steam Feedwater Raw water Treated water Potable water Aux. cooling system Firefighting system Clarified water Filtered water Water-intake system Circulating-water system Chemical dosing Station drains Fuel oil Fuel gas... 

First-pass metabolism is the elimination of an orally administed drug by the liver or sometimes the gut wall, before it reaches the systemic circulation. First-pass metabolism results in a decreased systemic bioavailability. 

Pharmacodynamics deals with the drag s action and effect within the body. After administration, most dra enter the systemic circulation and expose almost all body tissues to possible effects of the drug. All dra produce more than one effect in the body. The primary effect of a drag is the desired or therapeutic effect. Secondary effects are all other effects, whether desirable or undesirable, produced by the drag. 

When otic drugs are applied topically, the amount of drug that enters die systemic circulation is not sufficient to produce adverse reactions. Prolonged use of otic... 

Systemic overloading of calcium ionsin the systemic circulation resultsin acute hypercatcemic syndrome. Symptoms of hyper-catcemic syndrome indude elevated plasma calcium, weakness, lethargy, severe nausea and vomiting, coma, and, if left untreated, death. The nurse reportsany sgnsof hypercatcemic syndrome immediately to the primary health care provider. 

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