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Thirst, regulation

Blood pressure and electrolyte composition by regulating mechanisms involved with urine output, thirst, salt appetite, maintenance of plasma osmolarity, and vascular smooth muscle tone... [Pg.57]

This is a simpler, better understood emotional system. As with probably every other basic emotion, the hypothalamus is involved in thirst. So too is the endocrine system, which is also common for emotions. See Rosenzweig et al. (1996) on thirst, hunger, and temperature regulation. [Pg.33]

Q1 What factors promote the sensation of thirst and how is thirst related to the regulation of body water content ... [Pg.71]

Isotonicity of the extracellular space is regulated by (i.) thirst mechanism, (2.) ADH, and (S.) dilution and concentration potential of the kidneys. Maintenance of extracellular isovoiaemia is effected by a change in renal sodium excretion. For this reason, disturbances in the sodium supply primarily result in changes in the extracellular fluid volume. Isohydria is also continually regulated within the normal range. [Pg.289]

Thermoregulation Poor temperature-regulating mechanisms 1 shivering 1 metabolic rate i vasconstriction i thirst response i subjective awareness of temperature Medications affecting awareness, mobility, muscular activity, vasoconstrictor mechanisms CNS medications Phenothiazines Barbiturates Benzodiazepines Tricyclic antidepressants Narcotics Alcohol... [Pg.1908]

The thirst center is regulated by many of the same factors that determine AVP release. This center has a higher set point than the osmoreceptors and responds to osmolalities above 290mOsm/kg. Responses involving AVP, thirst, and the kidney are coordinated in a complex scheme to maintain plasma osmolality in healthy individuals within a narrow range (284 to 295mOsm/kg). [Pg.1992]

The sodium-to-water ratio in the body must be properly balanced or unfortunate effects may result. The hypothalamus area of the brain is fairly efficient at regulation of this ratio when sodium is high, thirst results when excess urination causes loss of water, the body also excretes sodium to help maintain the balance. People traveling long distances in desert or other dry climates may ingest salt (NaCl) as a way to retain water in their systems. The kidneys also play a role in sodium regulation. [Pg.59]

In the brain, the hypothalamus links the nervous system to the pituitary gland (hypophysis) and this acts on the endocrine system through a number of hypothalamic hormone releasing factors neurohormones (see Chapter 10). The hypothalamus is responsible for the regulation of body temperature, hunger, and thirst and for chronobiological rhythms. [Pg.243]

Fig. 4.10. Body fluid homeostasis (constant body water balance). Intake is influenced by availability of fluids and food, thirst, hunger, and the ability to swallow. The rates of breathing and evaporation and urinary volume influence water loss. The body adjusts the volume of urinary excretion to compensate for variations in other types of water loss and for variations in intake. The hormones aldosterone and antidiuretic hormone (ADH) help to monitor blood volume and osmolality through mechanisms regulating thirst and sodium and water balance. Fig. 4.10. Body fluid homeostasis (constant body water balance). Intake is influenced by availability of fluids and food, thirst, hunger, and the ability to swallow. The rates of breathing and evaporation and urinary volume influence water loss. The body adjusts the volume of urinary excretion to compensate for variations in other types of water loss and for variations in intake. The hormones aldosterone and antidiuretic hormone (ADH) help to monitor blood volume and osmolality through mechanisms regulating thirst and sodium and water balance.
Human vasopressin, or Arg-vasopressin, is chemicaiiy very simiiar to oxytocin and therefore sometimes is referred to as [Phe, Arg ]oxytocin (Fig. 7.15). The physioiogicai roie of vasopressin is the regulation of water reabsorption in the renal tubules (an antidiuretic action, thus often referred to as the antidiuretic hormone). In high doses, vasopressin promotes the contraction of arterioles and capillaries, resulting in an increase in blood pressure, thus the name vasopressin. An inadequate output of pituitary antidiuretic hormone can cause diabetes insipidus, which is characterized by the chronic excretion of large amounts of pale urine and results in dehydration and extreme thirst. [Pg.317]

Water intake is regulated in part by the thirst mechanism (see I Figure 15.9). When the body loses large amounts of water, salivary secretions decrease, and a dry feeling develops in the mouth. This and other sensations are recognized as thirst, and water is drunk to relieve the condition. The fluid intake compensates for the fluid lost, and balance is reestablished. [Pg.480]

Trace the events of the regulation of fluid balance by the thirst mechanism. [Pg.489]

Quite early in the course of these tracer studies it was noted that marked changes in the uptake of cysteine- S occur following periods of water deprivation. Wells found that in rats thirst causes a marked increase in the uptake of radioactivity in the supraoptic nucleus and to a lesser extent in the paraventricular nucleus. Talanti later observed that thirst accelerates the rate of disappearance of radioactivity from the supraoptic and paraventricular nuclei, as well as the disappearance of radioactivity from the neurohypophysis. These results indicated that thirst activates both the synthesis and release of neurosecretory hormones that regulate the function of the kidneys. [Pg.445]

Extracellular fluid balance is maintained through closely regulated loss and retention to ensure that the total level of fluid in the body remains constant. Mechanisms are in place for regulation of water loss, such as secretion of antidiuretic hormone (ADH) to stimulation retention of water in urine, which helps to prevent excessive fluid elimination. The mechanism of thirst (also stimulated by ADH, as well as by blood pressure) is used to stimulate the ingestion of fluids and fluid-containing foods. 3... [Pg.30]

Problems arise when there is a failure or a decrease in function in any of the fluid regulation mechanisms. For example, in aging, the thirst mechanism is suppressed. The elderly patient may not drink adequate fluids owing to a lack of the thirst drive, and hypovolemia could result. Problems also arise if the regulating mechanisms fail to excrete excess water from the body, such as might occur with renal failure, and fluid overload results. [Pg.85]


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See also in sourсe #XX -- [ Pg.380 , Pg.381 ]




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