Vascular organ of lamina terminalis

The vascular organ of lamina terminalis (or supraoptic crest) ^[1] is one of the circumventricular organs of the brain. Other circumventricular organs are the subfornical organ and the area postrema in the brainstem.

Anteroventral third ventricle region

The vascular organ of the lamina terminalis and the subfornical organ are both strongly interconnected with the median preoptic nucleus of the hypothalamus, and together these three structures comprise the anteroventral third ventricle region – the region anterior and ventral to the third ventricle. This region is very important in the regulation of fluid and electrolyte balance by controlling thirst, sodium excretion, blood volume regulation, and vasopressin secretion.

Function

The vascular organ of the lamina terminalis is one of the three sensory circumventricular organs providing information to other brain regions.^[2] The other circumventricular organs are secretory.

The vascular organ lacks a blood brain barrier, and so neurons in this region can respond to osmotic pressure factors that are present in the systemic circulation.^[3]

Some neurons in this organ are osmoreceptors, being sensitive to the osmotic pressure of the blood. These neurons project to the supraoptic nucleus and paraventricular nucleus to regulate the activity of vasopressin-secreting neurons. In a situation of lowered blood volume, secretion of renin by the kidneys results in the production of angiotensin II, which stimulates the vascular organ and the subfornical organ to complete a positive feedback loop.^[4] These neurons also project to the median preoptic nucleus which is involved in controlling thirst.

References

External links

• http://www.sci.uidaho.edu/med532/lamina.htm