Y

1 Hematocrit

J Plasma Oncotic Pressure

f Plasma Volume

FIGURE 10 Summary of cardiovascular and renal changes in pregnancy. ERPF, effective renal plasma flow; GFR, glomerular filtration rate.

infusions. Thus, as already described for renin and AVP, control mechanisms that govern ANF secretion respond normally to acute changes in volume but defend vascular volume at a higher set point.

Figure 10 summarizes the cardiovascular and renal changes produced in the first trimester and continued throughout gestation. Hormonal signals arising in the tro-phoblast and/or the ovary and acting directly on vascular smooth muscle and the osmoreceptors initiate the series of changes that ultimately increase placental perfusion. It is likely, but not established, that these peripheral effects are reinforced by complementary effects on regulatory centers in the brain. The adaptive value of most of these changes appears to reside in ensuring adequacy of uteroplacental perfusion while maintaining sufficient circulatory reserve to service the needs of the mother. The adaptive value of the increase in GFR is unknown, but it may facilitate excretion of fetal wastes and dietary toxins.

Keep Your Weight In Check During The Holidays

Keep Your Weight In Check During The Holidays

A time for giving and receiving, getting closer with the ones we love and marking the end of another year and all the eating also. We eat because the food is yummy and plentiful but we don't usually count calories at this time of year. This book will help you do just this.

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