Question

what is hypothalamo hypophysial system?discuss the regulatory factors secreted by hypothalamus?​

Answer 1

Answer:

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Answer 2

he hypothalamic–hypophysial portal system is the conduit that connects the brain to the anterior pituitary. The portal system is made up of two capillary beds, one in the median eminence and the other in the anterior pituitary. The portal capillary bed in the median eminence is fed from the superior hypophysial arteries, and is divided into an external and an internal plexus.83 The capillaries of the external plexus form a hexagonal, chicken wire–like mesh embedded in the external surface of the median eminence (Fig. 1-9). The interior of each hexagonal unit is filled with axon terminals and glial tissue, including tanycyte processes. The internal plexus consists of capillary loops that emanate from the external plexus and rise into the upper regions of the internal zone. Blood coming from the capillary plexus of the median eminence is carried into a capillary bed in the anterior pituitary by long portal veins. From the anterior pituitary capillary bed, portal blood drains into the cavernous and posterior intercavernous sinuses. The capillaries and veins of the portal system are fenestrated; thus, molecules that are normally blocked by the blood–brain barrier can readily pass into and out of the portal circulation. Although in their original description of the portal system, Popa and Fielding speculated that the portal system delivered pituitary hormones to the brain,84 observations in living animals have shown that portal blood generally flows from the median eminence to the anterior pituitary,85 delivering hypothalamic hormones, such as GnRH, to the secretory cells they control.