Posterior Pituitary Gland MARISSA MIARA, DEVON PARODI, TAMARA NEBRIGIC - TABLE 4

Posterior Pituitary (neurohypophysis)  It is arguable that the pituitary gland is not a gland  Collection of axonal projections from hypothalamus that terminate behind the anterior pituitary gland  These axons release peptide hormones into the capillaries of the hypopyseal circulation  Hormones are synthesized by the hypothalamus then are stored in the neurosecretory vesicles before being secreted by the posterior pituitary into the blood stream  Stores and secretes oxytocin and vasopressin

Location  Posterior Pituitary (neurohypophysis) is located in the posterior lobe of the pituitary gland.  Attached to the hypothalamus by the infundibulum

Hormones  The posterior pituitary only secretes 2 hormones: Vasopressin and Oxytocin  Vasopressin:  also called arginine vasopressin (AVP) and antidiuretic hormone (ADH)  Acts on the collecting ducts of the kidneys to facilitate reabsorption of water into the blood- reducing the volume of urine formed  Deficiency of vasopressin leads to excessive loss of urine which causes Diabetes Insipidus  Oxytocin:  Acts on certain smooth muscles  Stimulates contractions of uterus during birth  Stimulates release of milk for baby  Usually given to mothers to hasten birth

Homeostasis and Feedback loops  Vasopressin keeps blood pressure at a constant rate, keeping all autonomic nervous systems functioning properly  Hypothalamus senses changes in the body and notifies the pituitary gland if vasopressin or oxytocin is needed  Oxytocin is one of the only hormones with a positive feedback loop.

Releasing Hormones and Glands  Hypothalamus makes and releases inhibiting hormones for posterior pituitary gland

Hypersecretion Conditions  Acromegaly- causes enlargement in the extremities of the body  Cushing’s Disease- Causes excessive amounts of cortisol to be excreted  Prolactinoma- Causes excess amounts of prolactin

Hyposecretion Conditions  Adult Growth Hormone Deficiency- Fails to produce Growth Hormone  Diabetes Insipidus- Passing dilute urine, increased thirst and urination.  Hypopituitanism- Failure of the pituitary gland to produce one or more hormones it normally produces.

Medical Treatment  Medications via injections, patches, pills, nasal spray  Surgery  Some are untreatable

Sources   En.Wikipedia.org/wiki/posterior_pituitary  Emoryhealthcare.org/pituitary/treatments/index.html   anatomy-and-physiology-textbook/the-endocrine-system-16/the- pituitary-gland-hypophysis-155/the-posterior-pituitary-and- hormones-of-the-posterior-pituitary / anatomy-and-physiology-textbook/the-endocrine-system-16/the- pituitary-gland-hypophysis-155/the-posterior-pituitary-and- hormones-of-the-posterior-pituitary /  tml tml