Parathyroid glands control free floating calcium ions. It is more important to have calcium ions in the
blood than in the bone. Negative feedback loop allows for the bone, kidney and gut to release/increase
absorption of calcium when parathyroid hormones are secreted.
Corticotopin releasing hormone interacts with adrenal glands to form a double feedback loop as
glucocorticoid level increases.
2 cell types: anterior and posterior (adenohypophysis and neurohypophysis). Anterior is endocrine,
posterior is neuronal.
Posterior pituitary produces oxytocin and arginine vasopressin, caused by gene duplication diversion,
Anterior pituitary: Dopamine is THE prolactin-inhibiting hormone, derived from free tyrosine. There is
NO dopamine gene.
Posterior Pituitary Gland – an outgrowth of the hypothalamus, connected by the pituitary stalk.
Supraoptic and paraventricular ganglions send down axons in the pituitary stalk and synthesize oxytocin
and vasopressin. Prohormones processed while being transported down the axon, by the time it is
released, they are mature. Carried by neurophysins with a half life of 1-3 min.
Oxytocin: no known function in males. In females, the primary function is motor, parturition
(childbirth) uterus becomes very sensitive to oxytocin at the end of pregnancy (high number of
receptors produced for the end of pregnancy). Baby head stretches the cervix cause release of oxytocin.
Secondary effect of milk ejection.
Filled with colloid, which is made mostly of thyroglobulin, a huge protein of 700k Da. Thyroglobulin
provides the tyrosine residues for the thyroid hormones (VERY low % of thyroglobulin becomes thyroid
hormones). Controlled by TSH hormone from the pituitary. 15-20g, larger in females than males, only 3g
is needed to maintain physiology. Iodine is actively absorbed by the thyroid follicular cells, and only the
thyroid cells with special transporter are able to take up iodine. Iodine binds to TGB to form MIT and DIT
(mono and di iodotyrosines). 2 DIT into T4, 1 DIT and MIT to form T3.TSH production and release