Personal Resilience in Project Management 2 - TV Edit 1a.pdf
Pituitary Gland
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4. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragm sellae).
5. The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid bone in the middle cranial fossa at the base of the brain.
6. The pituitary gland secretes hormones regulating homeostasis, including tropic hormones that stimulate other endocrine glands.
7. It is functionally connected to the hypothalamus by the median eminence via a small tube called the Pituitary Stalk.
14. This is an unpaired small ovoid gland and is no longer than the end of the little finger.
15. It is located at the base of the brain and lies below the diencephalon in a depression of basis phenoidboneof the skull called Sella Turcica.
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17. The gland is connected to a region of the brain called the hypothalamus by the pituitary stalk. Directly above the pituitary gland and in front of the pituitary stalk are the crossing fibers of the optic nerves, called the optic chiasm.
18. On each side of the pituitary gland is the cavernous sinus. Through each cavernous sinus runs a carotid artery that carries blood to the brain, and important nerves that control eye movements.
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22. The anterior pituitary regulates several physiological processes including stress, growth, and reproduction.
23. Its regulatory functions are achieved through the secretion of various peptide hormones that act on target organs including the adrenal gland, liver, bone, thyroid gland, and gonads.
24. The anterior pituitary itself is regulated by the hypothalamus and by negative feedback from these target organs.
25. Disorders of the anterior pituitary are generally classified by the presence of over- or underproduction of pituitary hormones.
26. For example, a prolactinoma is a pituitary adenoma that overproduces prolactin. I
27. n Sheehan's syndrome of postpartum hypopituitarism, the anterior pituitary uniformly malfunctions and underproduces all hormones.
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29. Pars tuberalis The pars tuberalis, or "tubular part", forms a sheath extending up from the pars distalis and wrapping around the pituitary stalk. Its function is poorly understood.
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31. The secretion of hormones from the posterior pituitary is controlled directly by neurons in the hypothalamus (Marieb, 2004).
32. The connecting stalk between the hypothalamus and the lobes of the pituitary gland, the infundibulum, carries the hormones of the posterior pituitary from nuclei in the hypothalamus.
33. The hypothalmicsupraoptic nuclei manufacture anti-diruetic hormone and the hypothalmicparaventricular nuclei manufacture oxytocin.
34. These hormones are then stored in pituitary axons until their release is triggered (Marieb, 2004).
35. The anterior pituitary is a glandular secretory organ (Wheater, Burkitt & Daniels, 1987).
36. The secretion of hormones from the anterior pituitary is controlled by inhibiting and releasing factors secreted by neurons in the hypothalamus.
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40. It contains three types of cells - basophils, chromophobes, and colloid-filled cysts.
42. In human fetal life, this area produces melanocyte stimulating hormone or MSH which causes the release of melanin pigment in skin melanocytes (pigment cells).
50. Adrenocorticotropic Hormone (ACTH): Triggers the adrenal glands, which regulate stress response with the release of hormones such as cortisol and aldosterone.
54. it is released in large amounts after distension of the cervix and uterus during labor
55. after stimulation of the nipples, facilitating birth and breastfeedingreastfeeding.
56. Recent studies have begun to investigate oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, and maternal behaviors
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65. Effects of growth hormone on the tissues of the body can generally be described as anabolic (building up).
66. Like most other protein hormones, GH acts by interacting with a specific receptor on the surface of cells.
67. Increased height during childhood is the most widely known effect of GH. Height appears to be stimulated by at least two mechanisms
69. Thus, GH exerts some of its effects by binding to receptors on target cells, where it activates the MAPK/ERK pathway.
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71. The liver is a major target organ of GH for this process and is the principal site of IGF-1 production. IGF-1 has growth-stimulating effects on a wide variety of tissues.
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74. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with corticotropin-releasing hormone from the hypothalamus).
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77. ACTH acts at several key steps to influence the steroidogenic pathway in the adrenal cortex:
78. ACTH stimulates lipoprotein uptake into cortical cells. This increases the bio-availability of cholesterol in the cells of the adrenal cortex.
79. ACTH increases the transport of cholesterol into the mitochondria and activates its hydrolysis.
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84. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland.
85. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body.
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89. Prolactin is a peptide hormone discovered by Dr. Henry Friesen, primarily associated with lactation. In breastfeeding, the act of an infan suckling the nipple stimulates the production of oxytocin which stimulates the "milk let-down" reflex,which fills the breast with milk via a process called lactogenesis, in preparation for the next feed.
90. Pituitary prolactin secretion is regulated by neuroendocrine neurons in the hypothalamus, the most important ones being the neurosecretorytuberoinfundibulum (TIDA) neurons of the arcuate nucleus, which secrete dopamine to act on the dopamine-2 receptors of lactotrophs, causing inhibition of prolactin secretion. Thyrotropin releasing factor (thyrotropin-releasing hormone) has a stimulatory effect on prolactin release.
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93. They were first isolated by the Yale professor Aaron B. Lerner.
102. The inactive precursor protein is progressively hydrolyzed into smaller fragments (one of which is neurophysin I) via a series of enzymes.
103. The last hydrolysis which releases the active oxytocinnonapeptide is catalyzed by peptidylglycine alpha-amidatingmonooxygenase (PAM).
104. The activity of the PAM enzyme system is dependent upon ascorbate which is a necessary vitamin cofactor. By chance, it was discovered that sodium ascorbate by itself stimulated the production of oxytocin from ovarian tissue over a range of concentrations in a dose-dependent manner.
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108. The sequence is cys– tyr– ile – gln – asn – cys – pro – leu – gly- NH2 (CYIQNCPLG-NH2).
109. The cysteine residues form a sulfur bridge. Oxytocin has a molecular mass of 1007 daltons.
110. One international unit (IU) of oxytocin is the equivalent of about 2 micrograms of pure peptide.
111. The biologically active form of oxytocin, commonly measured by RIA and/or HPLC techniques, is also known as the octapeptide "oxytocin disulfide" (oxidized form), but oxytocin also exists as a reduced dithiolnonapeptide called oxytoceine.
123. Secretion in response to reduced plasma volume is activated by pressure receptors in the veins. atria, and carotids.
124. Secretion in response to increases in plasma osmotic pressure is mediated by osmoreceptors in the hypothalamus.
125. Secretion in response to increases in plasma cholecystokininis mediated by an unknown pathway.
126. The neurons that make AVP, in the hypothalamic supraoptic nuclei (SON) and paraventricular nuclei (PVN), are themselves osmoreceptors, but they also receive synaptic input from other osmoreceptors located in regions adjacent to the anterior wall of the third ventricle. These regions include the organumvasculosum of the lamina terminalis and the subfornical organ.
128. Ethanol(alcohol) acts as an antagonist for AVP in the collecting ducts of the kidneys, which prevents aquaporins from binding to the collecting ducts, and prevents water reabsorption.
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130. The AVP that is measured in peripheral blood is almost all derived from secretion from the posterior pituitary gland (except in cases of AVP-secreting tumours). However there are two other sources of AVP with important local effects:
131. Vasopressin is produced in the PVN and SON and travels down the axons through the infundibulum within neurosecretory granules that are found within Herring bodies, localized swellings of the axons and nerve terminals. These carry the peptide directly to the posterior pituitary gland, where it is stored until released into the blood.
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138. While most are benign, they can produce excessive amounts of a specific pituitary
139. hormone, crowd out the production of other hormones, and compress surrounding tissues.
140. Blood vessels and the optic nerves are in close proximity to the pituitary gland. Pressure from a tumor can cause headaches, visual disturbances, loss of vision, fatigue, weakness, and seizures, as well as a host of signs and symptoms related to diminished hormone production.
141. Other pituitary disorders can arise from inherited genetic mutations, be congenital, be due to trauma or an impaired blood supply, due to surgical or radiation treatment of a previous pituitary disorder, due to a malignant tumor (rare), or be due to causes that are not yet well understood.
142. The hormone deficiencies and excesses from these disorders can produce a variety of symptoms depending on which hormones and target tissues are affected.
143. When the hypothalamus is dysfunctional, pituitary hormone production is often affected.
154. Signs and symptoms: Pituitary tumors may manifest with signs and symptoms related to pituitary hypofunction, specific hormone(s) hypersecretion, and/or mass effect. Impingement on the chiasm or its branches by a pituitary tumor may result in visual field defects; the most common is bitemporalhemianopsia Lateral extension of the pituitary mass to the cavernous sinuses may result in diplopia, ptosis, or altered facial sensation.Among the cranial nerves, the third nerve is the most commonly affected. There is no specific headache pattern associated with pituitary tumors and, in some patients, the headache is unrelated to pituitary adenoma.
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156. Treatment: With exogenous GH is indicated only in limited circumstances and needs regular monitoring due to the frequency and severity of side-effects
157. Hypopituitarism: from a variety of causes including tumors, trauma, decreased pituitary blood supply, infection, sarcoidosis, an autoimmune process, radiation, surgical removal of the pituitary, or a side effect of pituitary surgery; results in a general decrease in pituitary hormone production.
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164. symptoms vary but include: upper body obesity, a rounded face, thin skin, pink streaks on the abdomen, muscular weakness, osteoporosis, high blood sugar, and high blood pressure
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167. Nelson’s Syndrome: may result when both adrenal glands are removed as part of the treatment for Cushing’s Disease; a pituitary tumor develops that produces ACTH .
168. Symptoms: cause darkening of the skin due to increased production of melanocyte stimulating hormone (MSH) disturbances, and delayed growth.