Speculations on Physicochemical Fluid Properties in Physiological Regulation

Speculations on physicochemical fluid properties in physiological regulation.

Physiological variability of fluid-regulation hormones in young women.

We tested the physiological reliability of plasma renin activity (PRA) and plasma concentrations of arginine vasopressin (P[AVP]), aldosterone (P[ALD]), and atrial natriuretic peptide (P[ANP]) in the early follicular phase and midluteal phases over the course of two menstrual cycles (n = 9 women, ages 25 +/- 1 yr). The reliability (Cronbach's alpha >/=0.80) of these hormones within a given phas...

Nectar: properties, floral aspects, and speculations on origin.

Although nectar is crucial for most pollinators, its evolutionary origin has received scant attention. Nectar is derived from the phloem solution. Both have high sugar concentrations (usually 10-30% solutes by fresh mass); the main solute in the phloem is sucrose, whereas nectar can also contain considerable amounts of fructose and glucose. The phloem, not the xylem, is the supplier of water to...

The physiological regulation of thirst and fluid intake.

Thirst is important for maintaining body fluid homeostasis and may arise from deficits in either intracellular or extracellular fluid volume. Neural signals arising from osmotic and hormonal influences on the lamina terminalis may be integrated within the brain, with afferent information relayed from intrathoracic baroreceptors via the hindbrain to generate thirst.

Physiological and physicochemical controls on foliar volatile organic compound emissions.

Plant leaves emit a broad spectrum of organic compounds that typically play multiple roles in plant protection. Furthermore, most of these compounds actively participate in tropospheric chemistry. There has been rapid progress in understanding how the emission of volatiles is regulated, mostly focusing on the biochemical controls over compound production. However, physicochemical characteristic...