hypothalamus & pituitary Flashcards
where is the pituitary gland located
The pituitary gland is located in the middle of the base of the brain, below the hypothalamus
why is the hypothalamus important
- has inputs from the thalamus, reticular activating system, limbic system, eyes
- Close to the regions controlling: autonomic nervous system, emotional response, temperature, food intake, water balance, sleep-wake cycles
- Has connections with pituitary via hypothalamic-hypophyseal tract, hypophyseal portal system
what are the posterior pituitary hormones
- antidiuretic hormone (ADH)
2. Oxytocin
what is antidiuretic hormone
acts on the kidneys to stimulate water reabsorption
what is oxytocin
acts on the uterus to contract and acts on the ducts of the breasts to cause milk ejection
how are antidiuretic and oxytocin similar
both peptides
cyclical structures
9 amino acids with 2 different
how is oxytocin and ADH transported to the posterior pituitary
via the hypothalamic hypophyseal tract
where is oxytocin and ADH stored
in the nerve terminals of the posterior pituitary
how is oxytocin and ADH released
activity in the nerves of the hypothalamus induces the release of hormones from the pituitary
where is oxytocin synthesised
mainly in the paraventricular nucleus
where is ADH synthesised
mainly in the supraoptic nucleus
how does oxytocin induced contractions
uses IP3/DAG second messengers
what are the actions of oxytocin
- Stimulates myoepithelial cells of ducts in the breast to contract
- Suckling stimulates the release
- Contracts uterus
what is the stimulus for release of the antidiuretic hormone
- rise in blood osmolality
normal = 280mOsm/L - Fall in blood volume
what are the actions of antidiuretic hormone
- increase the permeability of collecting ducts in kidney and promotes water retention
via V2 receptors (cAMP second messenger), increase the number of aquaporins. - vasoconstriction, V1 receptor (IP3/DAG second messenger)
