The Anterior Pituitary develops from the _____, while the Posterior Pituitary develops from the ______.
The Anterior Pituitary develops from the pharyngeal arches, while the Posterior Pituitary develops from the third ventricle of the brain.
The hypothalamus is divided into four regions from Rostral to Caudal:
- 1. Preoptic area: (contains the medial and lateral preoptic nucleus)
- 2. Anterior/Supraoptic Area: (anterior hypothalamic nucleus, supraoptic nucleus, paraventricular nucleus, suprachiasmatic nucleus)
- 3. Middle/Tuberal Region: dorsomedial, ventromedial, arcuate nuclei
- 4. Posterior/Mammilary Region: Mammilary, and posterior nulei
The hypothalamus releases the following 7 trophic hormones:
- 1. Gonadotropin Releasing Hormone (GnRH)
- 2. Thyrotropin Releasing Hormone (TRH)
- 3. Corticotropin Releasing Hormone (CRH)
- 4. Growth Hormone Releasing Hormone (GRH)
- 5. GRIH (leads to release of Somatostatin)
- 6. Prolactin Releasing Hormone (PRH)
- 7. PRIH (inhibits prolactin release)
Describe the drug: BROMOCRIPTINE
Bromocriptine is a Dopamine Agonist often used in treatment for Hyperprolactinemia
There are five specific lobes of the Hypothalamus which release the trophic hormones and inhibiting hormones. List these lobes and what they release
- 1. Arcuate Nucleus: releases GHRH and Dopamine
- 2. Paraventricular Nucleus: TRH and CRH
- 3. Periventricular Nucleus: Somatostatin
- 4. Preoptic Area: GnRH
- 5. Dorsal Anterior Periventricular: PRF (prolactin releasing factors)
Describe the condition of: Craniopharyngioma
Craniopharyngioma is a tumor of the Hypothalamic region and is most common in children and adolescents.
Leads to deficiency of FSH, LH, GH, TSH, and ACTH.
Diabetes Insipidus (salt and water disorder) is common in 15% of patients.
Being a hypothalamic disorder, other than general symptoms the patient may present with abnormal thirst, temperature disorders, abnormal eating feelings and behavior, and general behavior disorders
Describe the condition of: Sellar/Suprasellar Tumors - Pituitary Adenomas
Is a tumor of the Pituitary Gland
Can lead to multiple endocrine effects such as hypersecretion of GH (may cause acromegaly in adults or gigantism in children), Prolactin (may cause infertility, amenorrhea, galactorrhea), and ACTH (may cause Cushing's Syndrome)
Larger tumors may potentially cause under secretion of pituitary hormones, effecting GH and the gonadotropes first, followed by TSH and ACTH.
Describe the condition of: Pituitary Apoplexy
A hemorrhage within a tumor
What are the surgical methods for reaching the pituitary/hypothalamus?
The two approaches are Trans-sphenoidal or Trans-frontal
Describe the condition of: Sheehan's Syndrome
Condition characterized by a severe uterine hemorrhage during childbirth due to Placentia Previa (insertion of placenta close to the cervix of the uterus) where the resulting blood loss leads to tissue death of the Pituitary Gland (Hypopituitarism)
Describe the condition of: Simmond's Syndrome
A pituitary disorder due to trauma, vascular lesions, or tumors leading to Hypopituitarism in which ALL of the pituitary secretions are deficient
The blood to the pituitary is supplied by the ______.
The blood to the pituitary is supplied by the internal carotid arteries, as well as the superior, inferior, and middle hypophysial arteries.
The venous drainage of the pituitary is by the _____.
The venous drainage of the pituitary is by the cavernous sinus, which drains into the superior/inferior sinuses, and finally the jugular vein.
Vassopressin (ADH) acts on two different receptors which cause different results. Breifl explain the two:
- V1 Receptor: ADH leads to vasoconstriction of vascular smooth muscle in the skin and blood vessels, as well as stimulation of gluconeogenesis in the liver
- V2 Receptor: located in the kidneys, activation of these receptors leads to increased reabsorption of water through deposition of water channels in the collecting tubule of the nephrons
The overall results of ADH secretion is increased arterial pressure
Detail the difference between Central and Nephrogenic Diabetes Inspires
Diabetes Insipidus is a deficiency of ADH
- Central: (Neurogenic, Pituitary, Hypophyseal) is a decrease in ADH secretion
- Nephrogenic: resistance to ADH leading to inability to reabsorb water or concentrate urine
Describe the condition of: Adipsic Hypernatremia
Caused by destruction of the hypothalamic osmoreceptors which regulate thirst and ADH secretion, leading to a lack of thirst, failure to drink proper fluid amounts, decreased blood volume, and decreased plasma sodium osmolarity, dehydration
Describe the condition of: Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
Characterized by excess ADH secretion and action. It can be a primary disease where the ADH secretion is dysfunctional, or secondary due to nonosmotic stimuli such as hypotension or glucocorticoid deficiency.
Name the synthetic drug of Oxytocin