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Pituitary Gland - Anatomy & Physiology (view source)
Revision as of 11:19, 2 January 2011
, 11:19, 2 January 2011→Action on the Blood Vessels
====Action on the Blood Vessels====
====Action on the Blood Vessels====
It causes vasoconstriction of blood vessels as a secondary function. It binds to V1 receptors on vascular smooth muscle and acts via the '''IP3 signal transduction pathway'''. It increases the arterial pressure. Normal physiological concentrations do not cause vasoconstriction, if severe hypovolaemic shock is suffered, lots of ADH is released due to decreased plasma volume - the amount of ADH released is relative to the degree of hypovoleamia. These very high levels are what is called ''vasoactive'' and help with a compensatory mechanism of increased vascular resistance. This increased vascular resistance increases arterial blood pressure. Stretch, or volume receptors in the veins and atria can detect a decrease in volume of the blood. This causes nervous impulses to be sent to the hypothalamus, resulting in an increase in ADH production, conserving water at the kidneys. This mechanism is only triggered by a large loss of volume, but results in a large amount of ADH being produced. It should be noted that thirst stimulation is the main method of correcting a dehydration status.
Stretch, or Volume receptors in the veins and atria can detect a decrease in volume of the blood. This causes nervous impulses to be sent to the hypothalamus, resulting in an increase in ADH production, conserving water at the kidneys. This mechanism is only triggered by a large loss of volume, but results in a large amount of ADH being produced.
It should be noted that Thirst Stimulation is the main method of correcting a dehydration status.
===Oxytocin===
===Oxytocin===