L2 Endocrine By Hani Laith PDF

Neural connections with posterior lobe of the pituitary gland:  The hormones released by posterior pituitary gland are synthesized in the cell bodies of large neurons located in the supraoptic and paraventricular nuclei of the hypothalamus.  Secretion from the posterior pituitary is contr...

Neural connections with posterior lobe of the pituitary gland:  The hormones released by posterior pituitary gland are synthesized in the cell bodies of large neurons located in the supraoptic and paraventricular nuclei of the hypothalamus.  Secretion from the posterior pituitary is controlled by nerve signals that originate in the hypothalamus and terminate in the posterior pituitary. Vascular connections with anterior lobe of the pituitary gland:  The portal hypophysial vessels form a direct vascular link (portal) between the hypothalamus and the anterior pituitary.  The blood that supplies the anterior pituitary comes from the lower hypothalamus. ‫اﻷﻣﺎﻣﯿﺔ ﯾﺄﺗﻲ‬ ‫اﻟﺪم اﻟﺬي ﯾﺰود اﻟﻐﺪة اﻟﻨﺨﺎﻣﯿﺔ‬.‫ﻣﻦ ﻣﻨﻄﻘﺔ ﻣﺎ ﺗﺤﺖ اﻟﻤﮭﺎد اﻟﺴﻔﻠﻲ‬  Secretion by the anterior pituitary is controlled by hormones called hypothalamic releasing and hypothalamic inhibitory hormones (or factors) secreted within the hypothalamus and then conducted to the anterior pituitary through these vessels.  ‫ﻧﺰﯾﻒ‬  Hemorrhage causes increased drinking even if there is no change in the osmolality of the plasma. ‫ﯾﺴﺒﺐ اﻟﻨﺰﯾﻒ زﯾﺎدة اﻟﺸﺮب ﺣﺘﻰ ﻟﻮ ﻟﻢ ﯾﻜﻦ ھﻨﺎك ﺗﻐﯿﯿﺮ ﻓﻲ‬.‫اﻷﺳﻤﻮﻟﯿﺔ ﻟﻠﺒﻼزﻣﺎ‬  Renin secretion is increased by hypovolemia  increase in circulating angiotensin II.  Angiotensin II act on: ‫ﯾﺰداد إﻓﺮاز اﻟﺮﯾﻨﯿﻦ ﻋﻦ طﺮﯾﻖ زﯾﺎدة ﻧﻘﺺ‬.‫ﺣﺠﻢ اﻟﺪم ﻓﻲ ﺗﻌﻤﯿﻢ اﻷﻧﺠﯿﻮﺗﻨﺴﯿﻦ اﻟﺜﺎﻧﻲ‬ 1. The subfornical organ in the diencephalon, to stimulate the neural areas concerned with thirst. ‫ ﻟﺘﺤﻔﯿﺰ اﻟﻤﻨﺎطﻖ اﻟﻌﺼﺒﯿﺔ اﻟﻤﻌﻨﯿﺔ ﺑﺎﻟﻌﻄﺶ‬،‫اﻟﻌﻀﻮ ﺗﺤﺖ اﻟﻔﺮﻧﻚ ﻓﻲ اﻟﺪﻣﺎغ‬ 2. The organum vasculosum of the lamina terminalis (OVLT)..(OVLT) ‫اﻟﻌﻀﻮ اﻟﻮﻋﺎﺋﻲ ﻟﻠﺼﻔﯿﺤﺔ اﻟﻄﺮﻓﯿﺔ‬  Subfornical organ and VOLT are highly permeable and located outside the blood–brain barrier  The increase in water intake during meal (prandial drink) is due to 1. Increased plasma osmolality that occurs after food is absorbed. 2. Action of one or more GI hormones on the hypothalamus ‫اﻟﻤﮭﺎدواﺣﺪ أو أﻛﺜﺮ ﻣﻦ ھﺮﻣﻮﻧﺎت اﻟﺠﮭﺎز اﻟﮭﻀﻤﻲ ﻋﻠﻰ ﻣﻨﻄﻘﺔ ﻣﺎ ﺗﺤﺖ‬ ‫ﻋﻤﻞ‬ MCQ Thirst is appetitive mechanism under hypothalamic control. Which of the followings is not a trigger for water intake A. Increased plasma osmolality B. Eating food C. Hypovolemia D. Hypertension E. Bleeding  Posterior pituitary hormones are vasopressin and oxytocin.  Human and most mammals vasopressin is Arginine ‫اﻹﻧﺴﺎن وﻣﻌﻈﻢ اﻟﺜﺪﯾﯿﺎت اﻟﻔﺎزوﺑﺮﯾﺴﯿﻦ ھﻮ أرﺟﯿﻨﯿﻦ‬ vasopressin (AVP) (AVP) ‫ﻓﺎزوﺑﺮﯾﺴﯿﻦ‬  Hippopotamia and most pigs vasopressin is lysine vasopressin (LVP) - arginine is replaced by lysine.  Some species of pigs and marsupials (like kangaroo) secrete a mixture of AVP and LVP. (‫ )ﻣﺜﻞ اﻟﻜﻨﻐﺮ‬.LVP‫و‬ ‫ﺑﻌﺾ أﻧﻮاع اﻟﺨﻨﺎزﯾﺮ واﻟﺠﺮاﺑﯿﺎت‬ AVP ‫إﻓﺮاز ﻣﺰﯾﺞ ﻣﻦ‬.‫ أﺣﻤﺎض أﻣﯿﻨﯿﺔ( ﻣﻊ ﺣﻠﻘﺔ ﺛﺎﻧﻲ ﻛﺒﺮﯾﺘﯿﺪ ﻓﻲ أﺣﺪ طﺮﻓﯿﮭﺎ‬9) ‫اﻟﻔﺎزوﺑﺮﯾﺴﯿﻦ واﻷوﻛﺴﯿﺘﻮﺳﯿﻦ ھﻤﺎ ﺑﺒﺘﯿﺪات ﻧﺎﻧﻮﯾﺔ‬  Vasopressin and oxytocin are nano-peptides (9 amino acids) with a disulfide ring at one end.  Vasopressin (AVP) and oxytocin (OT) are typical neurohormones “secreted into the blood by nerve cells)  AVP and OT are synthesized by magnocellular cell bodies and transported to the neuronal terminal in the posterior pituitary where they secreted in response to electrical activity in the ending ‫ ﺑﻮاﺳﻄﺔ أﺟﺴﺎم اﻟﺨﻼﯾﺎ اﻟﻤﻐﻨﻮﺳﺔ‬OT‫ و‬AVP ‫ﯾﺘﻢ ﺗﺼﻨﯿﻊ‬ ‫وﻧﻘﻠﮭﺎ إﻟﻰ اﻟﻄﺮف اﻟﻌﺼﺒﻲ ﻓﻲ اﻟﻐﺪة اﻟﻨﺨﺎﻣﯿﺔ اﻟﺨﻠﻔﯿﺔ ﺣﯿﺚ‬ ‫ﺗﻔﺮز اﺳﺘﺠﺎﺑﺔ ﻟﻠﻨﺸﺎط اﻟﻜﮭﺮﺑﺎﺋﻲ ﻓﻲ اﻟﻨﮭﺎﯾﺔ‬   Cells that secrete vasopressin and oxytocin are present in ‫اﻟﺨﻼﯾﺎ اﻟﺘﻲ ﺗﻔﺮز اﻟﻔﺎزوﺑﺮﯾﺴﯿﻦ واﻷوﻛﺴﯿﺘﻮﺳﯿﻦ ﻣﻮﺟﻮدة ﻓﻲ‬ 1. Supraotptic and paraventricular nuclei 2. Suprachiasmatic nuclei (AVP only) 3. Those in gonads 4. Those in adrenal gland 5. Those in thymus (Oxytocin only)  Paraventricular nuclei project to the brainstem and spinal cord. They are involved in cardiovascular control ‫ إﻧﮭﻢ ﯾﺸﺎرﻛﻮن ﻓﻲ اﻟﺘﺤﻜﻢ ﻓﻲ اﻟﻘﻠﺐ واﻷوﻋﯿﺔ اﻟﺪﻣﻮﯾﺔ‬.‫ﻣﺸﺮوع اﻟﻨﻮى ﺷﺒﮫ اﻟﺒﻄﯿﻨﯿﺔ إﻟﻰ ﺟﺬع اﻟﺪﻣﺎغ واﻟﺤﺒﻞ اﻟﺸﻮﻛﻲ‬ MCQ The hormones of the posterior pituitary gland are synthesized in brain and other organs in the body. Which of the following is not true about these hormones A. Oxytocin is present in the thymus B. AVP and oxytocin are synthesized in the gonads and the adrenal gland C. Oxytocin-secreting neurons are found in the suprachiasmatic nuclei D. AVP and oxytocin are found in the endings of neurons that project from the paraventricular nuclei to the spinal cord E. AVP and oxytocin are synthesized by magnocellular cells in the supraotptic nuclei Mechanism of action of AVP  AVP also called anti-diuretic hormone (ADH)  It increases the permeability of the collecting ducts. Consequent effect  This allow water to enter the hypertonic interstitium of the renal pyramids  Net water retention  The urine become concentrated (hypertonic)  The urine volume decreases  The plasma osmolality decrease Absence of AVP causes:  Hypotonic urine.  Urine volume increases  Net water loss  The plasma osmolality increases Mechanism of action of Oxytocin  Contraction of the myoepithelial cells line the ducts of the breast *  Contraction of uterine smooth muscles ** Consequent effect  Milk ejection  Accelerate delivery - luteolysis  * This contraction squeezes the milk out of the alveoli of the lactating breast into the large ducts (sinuses) and thence out of the nipple (milk ejection).  ** The sensitivity of the uterine musculature to oxytocin is enhanced by estrogen and inhibited by progesterone (direct oxytocin receptor inhibition). Anterior pituitary hormones are 6 hormones: 1. Adrenocorticotropic hormone (corticotropin, ACTH) Polypeptide, β-lipotropin (β-LPH), is secreted with ACTH, but its physiologic role is unknown. 2. Thyroid- stimulating hormone (thyrotropin, TSH). 3. Growth hormone (GH) 4. Follicle stimulating hormone (FSH) and Luteinizing hormone (LH) 5. Prolactin (PRL)  Releasing and inhibiting factors “hypophysiotropic hormones” synthesized by hypothalamus and carried through portal hypophysial vessels to the pituitary where they control anterior pituitary hormone secretion. Hypophysiotropic hormones receptors  All are GPCR type  Found in the tropes of pituitary gland  Human CRH receptors: hCRH-I stimulate ACTH release; while and hCRH-II (have unknown function in the brain) Hypophysiotropic binding proteins  All these hormones (EXCEPT CRH) do not have binding proteins  CRH-binding protein function or role: 1. In the peripheral circulation it inactivates CRH 2. In the cytoplasm of pituitary corticotropes it internalizes CRH receptors MCQ: There are six established hypothalamic releasing and inhibiting (or hypophysiotropic) hormones. All do nor have known binding proteins EXCEPT A.Thyroid stimulating hormone B.Growth hormone releasing hormone C.Gonadotropin releasing hormone D.Corticotropin-releasing hormone E.Prolactin releasing hormone