Vasopressin is released once the osmoreceptors
in the hypothalamus detect an increase in serum osmolality or the baroreceptors detect hypovolaemia.
The MnPO receives inputs from the circumventricular organs and peripheral osmoreceptors
with reciprocal connections with paraventricular nucleus of hypothalamus (PVN), parabrachial nucleus, and ventrolateral medulla that are involved in cardiovascular regulations [14, 27-31].
However, simultaneously with the activation of facilitatory mechanisms, increased activity of osmoreceptors
produced by hyperosmolarity also activates LPBNinhibitory mechanisms, which strongly curb sodium appetite (43,45) (Figure 1).
If you get too little liquid, it's going to shrink your cells, and osmoreceptors
in your brain and other parts of your body are going to sense that cells need water.
in the hypothalamus and heart/blood vessel baroreceptors detect changes in plasma concentrations, producing or reducing anti-diuretic hormone (ADH) concentrations to increase, or decrease water absorption respectively (von Duvillard, 2004).
It appears as though the osmoreceptors
are 'reset' at a lower level to avoid a continuous diuresis.
Another interesting observation is the localization of AQP4 in the neurohypophysis, where osmoreceptors
control the release of ADH by an undefined process.
GFR, on the other hand, is influenced by volume sensors, osmoreceptors
, and arterial oncotic pressure.
Two afferent pathways, one from baroreceptors and one from osmoreceptors
, control the secretion of AVP in the presence of hypovolemia or hyperosmolality.
Dry mucous membranes, hyperosmolality, and reduced plasma volume activate hypothalamic osmoreceptors
, which trigger thirst and stimulate the secretion of ADH from the posterior pituitary.