endocrine system lecture 3 week 3 case study with answers summary - Understanding Pathophysiology PDF

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endocrine system lecture 3 week 3 case study with answers summary part 2...

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Huether: Understanding Pathophysiology, First Canadian Edition Chapter 18: Mechanisms of Hormonal Regulation Case Study with Answers MN is a 58-year-old man who has a history of acromegaly—a hormonal disorder where the pituitary gland produces an excess of growth hormone. This disorder results in enlarged hands, feet, and facial features. The cause of his acromegaly is a benign pituitary tumour. His acromegaly did not impact his life at first; however, he has started to get headaches and experience limited joint mobility over the past few months. 1. MN is started on Octreotide, a medication to treat his acromegaly. Which hormone inhibits the release of growth hormone (GH) and thyroid-stimulating hormone (TSH), that Octreotide mimics in its action? a. Thyrotropin-releasing hormone (TRH) b. Somatostatin c. Growth hormone-releasing hormone (GHRH) d. Substance P ANS: B. Somatostatin. Somatostatin inhibits the release of GH and TSH. Thyrotropin-releasing hormone (TRH) stimulates the release of TSH and modulates prolactin secretion. Growth hormonereleasing hormone (GHRH) stimulates the release of GH. Substance P inhibits the synthesis and release of ACTH. Substance P also stimulates the secretion of GH, folliclestimulating hormone, luteinizing hormone, and prolactin. 2. MN’s pituitary tumour is not impacting his posterior pituitary. What are the two hormones released from the posterior pituitary, and what impact do they have on MN’s body? ANS: The two hormones released from the posterior pituitary are antidiuretic hormone (ADH) and oxytocin. ADH increases the permeability of the distal renal tubules and collecting ducts. This increased permeability leads to increased water reabsorption into the blood, thus concentrating the urine and reducing serum osmolality. Oxytocin has a similar effect as ADH in men, and may also affect sperm motility. In women, oxytocin results in the milk-ejection/letdown reflex, and stimulates uterine contractions. 3. MN has recently moved to Iqaluit, Nunavut, where the sun rises before 0300h in the morning, and sets at 2300h at night. He has been having trouble sleeping through the night with the increased light. His medical team suggests he try melatonin supplements. Where is melatonin naturally secreted in the body, and what is its role? ANS: Melatonin release is stimulated by exposure to dark and inhibited by light 1

exposure, and is secreted by the pineal gland located near the centre of the brain. It is synthesized from tryptophan, which is first converted to serotonin and then to melatonin. Melatonin regulates the circadian rhythm, which is the body’s natural clock. Melatonin supplementation has been used therapeutically in humans to help with sleep disturbances.

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