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更多“Urinary system is composed of kidney, ureter, urinary bladder and urethra. Please write down compone…”相关的问题
A．balance electrolyte levels
B．balance water
C．excreteunnecessary water
D．productenzyme
A.digestive
B.immune
C.defence
D.urinary
The argument in the passage leads most naturally to which of the following conclusions？
A．A low output of urinary kallikrein is a likely cause of high blood pressure in children.
B．The kallikrein-kinin system plays an important role in the regulation of blood pressure.
C．Essential hypertension may have biochemical precursors which may be useful predictors in children.
D．The failure of the body to produce sufficient amounts of kinins is the cause of essential hypertension.
In 1971, a study of 700 children, ages 2 to 14, used a special blood pressure recorder which minimizes observer error and allows for standardization of blood pressure readings. Before then, it had been well established that the blood pressure of adults aggregates familially, that is, the similarities between the blood pressure of an individual and his siblings are generally too great to be explained by chance. The 1971 study showed that familial clustering was measurable in children as well, suggesting that factors responsible for essential hypertension are acquired in childhood. Additional epidemiological studies demonstrated a clear tendency for the children to retain the same blood pressure patterns, relative to their peers, four years later. Thus, a child with blood pressure higher or lower than the norm would tend to remain higher or lower with increasing age.
Meanwhile, other investigators uncovered a complex of physiologic roles--including blood pressure--for a vasoactive (作用于血管的)system called the kallikrein-kinin(血管舒缓酶－激酞原)system. Kallikreins are enzymes in the kidney and blood plasma which act on precursors (先兆) called kininogens to produce vasoactive peptides(酞)called kinins. Several different kinins are produced, at least three of which are powerful blood vessel dilators. Apparently, the kallikrein-kinin system normally tends to offset the elevations in arterial pressure that result from the secretion of salt-conserving hormones such as aldosterone(醛固酮) on the one hand and from activation of the sympathetic nervous system (which tends to constrict blood vessels) on the other hand.
It is also known that urinary kallikrein excretion is abnormally low in subjects with essential hypertension. Levels of urinary kallikrein in children are inversely related to the diastolic blood pressures of both children and their mothers. Children with the lowest kallikrein levels are found in the families with the highest blood pressure. In addition, black children tend to show somewhat lower urinary kallikrein levels than white children, and blacks are more likely to have high blood pressure. There is a great deal to be learned about the biochemistry and physiologic roles of the kallikrein-kinin system. But there is the possibility that essential hypertension will prove to have biochemical precursors.
The author is primarily concerned with______.
A．questioning the assumption behind certain experiments involving children under the age of 15
B．describing the new scientific findings about high blood pressure and suggesting some implications
C．describing two different methods for studying the causes of high blood pressure
D．revealing a discrepancy between the findings of epidemiological studies and laboratory studies on essential hypertension
In 1971, a study of 700 children, ages 2 to 14, used a special blood pressure recorder which minimizes observer error and allows for standardization of blood pressure readings. Before then, it had been well established that the blood pressure of adults aggregates familially, that is, the similarities between the blood pressure of an individual and his siblings are generally too great to be explained by chance. The 1971 study showed that familial clustering was measurable in children as well, suggesting that factors responsible for essential hypertension are acquired in childhood. Additional epidemiological studies demonstrated a clear tendency for the children to retain the same blood pressure patterns, relative to their peers, four years later. Thus, a child with blood pressure higher or lower than the norm would tend to remain higher or lower with increasing age.
Meanwhile, other investigators uncovered a complex of physiologic roles-including blood pressure-for a vasoactive (作用于血管的) system called the kallikrein-kinin (血管舒缓酶-激酞原 ) system. Kallikreins are enzymes in the kidney and blood plasma which act on precursors (先兆) called kininogens to produce vasoactive peptides(酞)called kinins. Several different kinins are produced, at least three of which are powerful blood vessel dilators. Apparently, the kallikrein-kinin system normally tends to offset the elevations in arterial pressure that result from the secretion of salt-conserving hormones such as aldosterone(醛固酮) on the one hand and from activation of the sympathetic nervous system (which tends to constrict blood vessels) on the other hand.
It is also known that urinary kallikrein excretion is abnormally low in subjects with essential hypertension. Levels of urinary kallikrein in children are inversely related to the diastolic blood pressures of both children and their mothers. Children with the lowest kallikrein levels are found in the families with the highest blood pressure. In addition, black children tend to show somewhat lower urinary kallikrein levels than white children, and blacks are more likely to have high blood pressure. There is a great deal to be learned about the biochemistry and physiologic roles of the kallikrein-kinin system. But there is the possibility that essential hypertension will prove to have biochemical precursors.
The author is primarily concerned with ______.
A．questioning the assumption behind certain experiments involving children under the age of 15
B．describing the new scientific findings about high blood pressure and suggesting some implications
C．describing two different methods for studying the causes of high blood pressure
D．revealing a discrepancy between the findings of epidemiological studies and laboratory studies on essential hypertension
No matter where it is used, "Flextime" system has proved ______.
A．entirely effective
B．a complete failure
C．to be disliked by the employers
D．too difficult to carry out
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