Hypothalamus and Pituitary Gland By: Stephanie, Noah, Esten, and Katie Endocrine Gland: Hypothalamus and Pituitary Gland By: Stephanie, Noah, Esten, and Katie

  The Endocrine System Overview: Composed of hormone secreting glands Together they regulate: body growth, metabolism, and sexual development and function Each hormone can affect several organs, once secreted into the bloodstream Entire system is regulated by feedback

Pituitary Gland:   Pituitary gland is “master” of the endocrine system Produces hormones which control functions of other endocrine glands Also known as the Hypophysis Same size as a pea, located at the base of the brain Attached to hypothalamus via nerve fibres Pituitary gland consists of the - anterior lobe, intermediate lobe, and the posterior lobe All three lobes are responsible for the production of various hormones

Pituitary Gland has two separate functions: Anterior Pituitary “classical gland” Composed of cells which secrete protein hormones Posterior Pituitary An extension of the hypothalamus Composed mainly of the axons of the hypothalamic neurons These neurons extend downward as a large bundle, behind the anterior pituitary

The Hypothalamus Controls many bodily functions Located in middle base of the brain Regulates: satiety (state of being fed/gratified to capacity), metabolism, and body temperature The hypothalamus is connected to the anterior pituitary via vascular connections Hypothalamic hormones control the secretion of anterior pituitary hormones Many of these hormones are secreted into an artery, which carries them to the pituitary

The Vascular Connections of the Hypothalamic-Hypophyseal Portal  

Hormone production, secretion, release, and effect: The hypothalamus releases two kinds of hormones into the pituitary gland(anterior). They are known as Releasing hormones and Inhibiting hormones: - Releasing hormones control the release of other hormones - Inhibiting hormones inhibit the release of other hormones Hormones Secreted by Anterior Lobe include: Growth Hormone(GH), Thyroid-stimulating hormone(THS), Andrenocorticotrophic Hormone(ACTH), Prolactin, Luteinizing Hormone(LH), Follide-stimulating hormone. Hormones secreted by Posterior Pituitary: Antidiuretic Hormone, oxytocin. 

Hormone Structure Target Effect Growth Hormone Protein Hormone. Built from a long chain of amino-acids(approx. 190) Liver growth and metabolism Thyroid- Stimulating Hormone large glycoproteins composed of alpha and beta subunits Thyroid gland Stimulates secretion of THS Andrenocorticotrophic Hormone   Adrenal gland(cortex) Stimulates the adrenal cortex Prolactin single chain protein hormone(194-199 amino-acids) Mammary gland milk production Lutenizing Hormone Ovary and testis reproduction hormone Follide-Stimulating Hormone Antidiuretic Hormone nine amino acid peptide  Kidney water conservation Oxytocin milk ejection, muscle contractions at birth

THS(Thyroid-stimulating Hormone) GH(Growth Hormone) THS(Thyroid-stimulating Hormone) -Somatostatin (from the liver) helps inhibit GH production. -When GH is secreted into Blood stream it produces IGF-1(insulin like-growth factor) -IGF-1 causes bone growth, along with the growth of other tissues in the body - It also sends signals to puitary gland when GH levels are too high to reduce GH production - Once TSH are secreted into the bloodstream, the Thyroid gland produces thyroid hormones(T3 and T4)

Prolactin ACTH(Andrenocorticotrophic Hormone) ACTH functions in many ways: 1.Regulates glucose levels 2.Increases Fat in the Body 3.Helps to defend against infection 4. Helps body respond to stress -Stimulates milk production in the breast. -high estrogen and progesterone levels prevent milk production. - After delivery, estrogen and progesterone levels decrease, and prolactin stimulates the secretion of milk by alveolar cells in the breast, allowing milk to be produced.

LH(Luteinizing Hormone) and FSH(Follide-stimulating Hormone) - GnRH(Gonadotrophin releasing hormone) enters anterior pituitary, which allows for the production of LH and FSH. - Both Hormones play a large role in producing reproductive hormones.

ADH(Antidiuretic Hormone) Oxytocin Really good website on hormones in Hypothalamus and Pituitary Gland: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/overview.html

ONE Homeostatic Mechanism of the hypothalamus and pituitary gland: Maintaining blood pressure

Initial Stimulation Baroreceptors –sensory receptors that monitor blood flow by the increase/decrease diameter of blood vessels If the arterial walls were to expand, this would sense the baroreceptors which would stimulate sensory nerves Sensory nerves carry the stimulation to the hypothalamus to initiate the release of multiple hormones

Hypothalamus Response Secretes corticotrophin-releasing hormone (CRH); this hormone stimulates the pituitary gland to secrete a hormone called adrenocorticotropic Adrenocorticotropic hormone triggers the adrenal glands to release aldosterone and cortisol Aldosterone aids in regulation of blood pressure and regulates water balance in body, inhibiting sodium increases Cortisol is produced by adrenal glands, aids in maintaining blood pressure but is also involved in the negative feedback loop Release of excess cortisol will activate the hypothalamus to stop producing CRH

Another Hypothalamus Response Hypothalamus is electrically stimulated, and secretes the antiduretic hormone (ADH); this hormone is stored in the posterior pituitary ADH detects salt concentration in extra cellular fluid by osmoreceptors in the hypothalamus ADH is responsible for diffusion of free water, back into blood, increasing pore permeability

Negative feedback loop When the water level is high in your blood, this acts as a negative feedback to inhibit the secretion of ADH Re-absorption of more water to dilute sodium, results in less urine produced A lack of ADH causes the kidneys to become impermeable to water, resulting in less absorption of water into the blood. When the kidneys are impermeable to water, urination will occur more often

Pituitary Gland Disorders Very rarely are they caused by anything other than over/under production of a hormone. The over/under production is most often caused by a tumor commonly called an adenoma if it’s benign.

Characteristics of a Pituitary Tumor The tumor can restrict the production of hormones (sometimes only restricts specific ones, disturbing a delicate balance). The tumor can also enhance the production of hormones. This also poses a problem because once again the balance of hormones is disturbed. Finally the tumor can have such a little effect that it goes unnoticed until it grows too large and presses onto the rest of the brain. For the most part pituitary tumors are caused by injury.

Disorders include: Combined Treatment: Acromegaly: caused by an excess of GH (growth hormone), the disorder normally stems from a tumor on the pituitary. It can be the cause of type 2 diabetes, high blood pressure and arthritis. When this disorder occurs in children it usually causes them to develop gigantism. Galactorrhea: caused by a hormone, either produced by the pituitary gland, or its production is linked to the pituitary. The disorder leads to a milky discharge (green or yellow) from the nipples, generally it occurs in women but it has occurred to men too. In addition it can also cause impotence, irregular periods and vision loss. Combined Treatment: The treatment of a pituitary tumor is usually a surgery, depending on the location, size and overall difficulty to reach. Other methods include radiation and medical treatment (does not provide a cure).

Hypothalamus Disorders As the hypothalamus is known for its homeostatic mechanisms its function directly regulates the rest of the body. Any disorder of the hypothalamus would have a large impact on the homeostatic mechanisms in the body.

Specific Disorders There are few actual diseases that are linked to the hypothalamus, more often; it is the symptoms of ineffective homeostatic mechanisms that present themselves. The symptoms include; overwhelming body temperature, low body temperature, high/low blood pressure and disarray in any other homeostatic mechanism. The hypothalamus is involved in every feedback mechanism, whenever the hypothalamus is disturbed all other glands become disturbed because of it.

Information Resources: "Anatomy of the Endocrine System". eMedicineHealth. December 1, 2008 http://www.emedicinehealth.com/anatomy_of_the_endocrine_system/article_em.htm  "Endocrinology Health Guide". University of Maryland Medical Center. May 23, 2006 http://www.umm.edu/endocrin/pitgland.htm  Bowen, R.A.. "Functional Anatomy of the Hypothalamus and Pituitary Gland". September 4, 2001 http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/anatomy.html http://www.aeron.com/new_page_27.htm http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/adh.html http://www.lionden.com/ap1out-endo.htm http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pituitary.html http://biology.clc.uc.edu/Courses/bio105/kidney.htm http://nsbri.tamu.edu/HumanPhysSpace/focus4/ep-urinecontrol.html http://www.medindia.net/patients/patientinfo/acromegaly-glandsinvolved.htm http://www.endocrinologycentral.com/endothyroidFAQ.asp http://www.creationofman.net/chapter3/chapter3_5.html http://courses.washington.edu/conj/bess/hyperprolactinemia/hyperprolactinemia.htm http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/tsh.html http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/overview.html

Picture Sources: http://www.hyperthyroidism101.com/thyroid-gland-lg.jpg http://www.dailygalaxy.com/photos/uncategorized/2007/05/23/blue_brain_5.jpg http://blog.wired.com/photos/uncategorized/2007/03/15/brain.jpg http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/sagpitbig.jpg http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/acth.html http://firstaidzone.com/shop/images/categories/blood-pressure.gif http://www.sciencedaily.com/images/2008/01/080130092102.jpg http://courses.washington.edu/conj/bess/hyperprolactinemia/lactation.png http://www.creationofman.net/chapter3/res/52.jpg http://www.creationofman.net/chapter3/res/41.jpg http://arthritis-research.com/content/6/3/98