Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Hormonal breast enhancement wikipedia , lookup
Signs and symptoms of Graves' disease wikipedia , lookup
Hormone replacement therapy (male-to-female) wikipedia , lookup
Hyperandrogenism wikipedia , lookup
Growth hormone therapy wikipedia , lookup
Pituitary apoplexy wikipedia , lookup
Hypothalamus wikipedia , lookup
Hypothyroidism wikipedia , lookup
HAPS –I Advanced Neuroendocrine Biology 2009 Paula Curbo Hill College 112 Lamar Drive Hillsboro, TX 76645 [email protected] (254) 659-7866 Learning Module on Hypothyroidism This is a two part learning module to be used during lecture, during lab, or to be assigned as homework. It is intended for students that are taking the first year of human anatomy and physiology. Most students should be able to complete the module within 30 minutes if they have had prior exposure to the material. Part One is a learning activity intended to check student understanding of the negative feedback regulation of the hypothalamus and pituitary gland. Part Two is an interrupted case study relating to hypothyroidism. Part A is to be given to the student first. Part B is to be given after the completion of Part A. Part One and Part two may be used together or independently. They have been designed to complement each other, aiding in student understanding. Part One Negative Feedback Regulation of Hypothalamus and Pituitary Gland by Serum Levels of T4, T3 The hypothalamus and pituitary gland are regulated by a negative feedback mechanism resulting in the fluctuation of serum levels of thyroid hormone (T4 and T3) around a set point. Fill in the boxes on the following page with the terms in Table 1 to illustrate this negative feedback control of the hypothalamus and anterior lobe of the pituitary gland. Fill in the circles with a + or – sign to show whether a stimulatory or inhibitory effect is taking place. Table 1 Anterior Pituitary Most body cells; metabolism stimulated by T4, T3 Hypothalamus Increased T4, T3 Serum levels of T4, T3 lowered as cells use T4, T3 Thyroid gland + - Negative Feedback Regulation of Hypothalamus and Pituitary Gland by Serum Levels of T4, T3 ↓Serum T4, T3, ↑Exercise, Stress Malnutrition, ↓Serum Glucose, Sleep Releases TRH; TRH Targets Releases TSH; TSH Targets Releases T4, T3 T4, T3 Target Answer Key Negative Feedback Regulation of Hypothalamus and Pituitary Gland by Serum Levels of T4, T3 ↓Serum T4, T3, ↑Exercise, Stress Malnutrition, ↓ Serum Glucose, Sleep + - + Hypothalamus Releases TRH; TRH Targets - Anterior Pituitary Releases TSH; TSH Targets Thyroid Gland Increased T4, T3 Most Releases T4, T3 T4, T3 Target Most body cells; metabolism stimulated by T4, T3 Serum Levels of T4, T3 lowered as cells use T4, T3 Part Two Case Study Onset of Hypothyroidism in Young Adult Female Part A Sasha, a 22 year old college graduate, spent her summer following graduation filling out job applications and going to interviews. She had not felt particularly well the last year of college and had trouble concentrating on completing her courses, but she attributed her symptoms to the stress of graduation and the transition into the work force. She was hoping to feel better after graduation but her symptoms continued and some even worsened throughout the summer. Sasha noticed she felt tired all the time and she sometimes had pain in her muscles and joints. Her hair began to fall out and her skin began to feel dry. She felt cold and slightly depressed all the time. It also occurred to her that constipation was becoming common. Her menstrual cycles were abnormally heavy and long. When her symptoms continued, Sasha finally decided to go to the doctor. At the clinic, her heart rate and blood pressure were both below average. The doctor thought of several possible problems and suspected a hormone disorder. 1. Based upon Sasha’s symptoms, what systems in the body were affected? 2. What potential hormones might be causing the problems? Part B The doctor suspects a problem with TSH and/or TH and orders a battery of blood tests. Sasha’s blood work indicated abnormal readings for the following tests: Shasha T4 3.1 µg/dl T3 uptake 16% T3 90 ng/dL TSH 41.1 mIU/L RBC count 3.38 mil/µL Hemoglobin 11.5 g/dL Hematocrit 32.2 % Normal Range 5 - 12.5 µg/dL 22 - 35% (This is an indirect measure of T4.) for 15 - 23 years 100 - 220 ng/dL 0.3 – 5 mIU/L 3.9 - 5.20 mil/µL 12.0 - 15.6 g/dL 35.0 - 46.0% All other blood tests showed normal readings. 3. What are the effects of thyroid stimulating hormone? 4. What are the effects of thyroid hormone on the body? 5. Sasha’s blood work indicated abnormally low levels of T3 and T4 and abnormally high levels of TSH. Do the results indicate a problem with the hypothalamus, the pituitary gland, or the thyroid gland? Why? 6. Why were TSH levels high while T4 and T3 were low? 7. Why were the RBC count, hemoglobin values, and hematocrit so low? Sasha was diagnosed with primary hypothyroidism and was placed on a thyroid replacement treatment consisting of levothyroxine. Answer Key Case Study Onset of Hypothyroidism in Young Adult Female Part A 1. Based upon Sasha’s symptoms, what systems in the body were affected? Nervous—lack of concentration, depression, fatigue; integumentary—brittle hair, dry skin; cardiovascular— bradycardia (slow heart rate); musculoskeletal—pain in muscles and joints; digestive— constipation due to slow peristalsis; reproductive—abnormal menstrual cycles. 2. What potential hormones might be causing the problems? Thyroid stimulating hormone (TSH) and/or thyroid hormone (TH) Part B 3. What are the effects of thyroid stimulating hormone? TSH promotes an increase in the size, number, and activity of the cells in the thyroid gland and stimulates the release of thyroid hormone (T3 and T4). 4. What are the effects of thyroid hormone on the body? Thyroid hormone (T3 and T4) increases the basal metabolic rate of cells, increases metabolism of proteins, carbohydrates and lipids, and affects the normal development and functioning of systems in the body. TH raises the heart rate, respiratory rate, and strength of muscle contraction. TH affects renal function by influencing the glomerular filtration rate. In females, the menstrual cycle is frequently affected. TH promotes alertness and the ability to think quickly. TH also has a calorigenic (heat production) effect on the body. Since almost all cells are affected by thyroid hormone, insufficient levels result in wide spread complications. 5. Sasha’s blood work indicated abnormally low levels of T3 and T4 and abnormally high levels of TSH. Do the results indicate a problem with the hypothalamus, the pituitary gland, or the thyroid gland? Why? Since T3 and T4 were low while TSH levels were high, the problem is with the insufficiency of the thyroid gland to secrete thyroxine (T4) and triiodothyronine (T3). Had T3, T4 and TSH levels all been below the normal range, the disorder would be attributed to the insufficiency of the hypothalamus to secrete thyrotropin-releasing hormone (TRH). 6. Why were TSH levels high while T4 and T3 were low? TSH stimulates the thyroid gland to secrete mainly thyroxine, some of which is converted to triiodothyronine. In an underactive thyroid gland, the hypothalamus releases thyrotropin-releasing hormone which stimulates the anterior pituitary to release more and more TSH. 7. Why were the RBC count, hemoglobin values, and hematocrit so low? Besides the lowered metabolism in the red bone marrow, Sasha’s loss of blood from her heavy menstrual cycles would lower these readings. References Andrews, Marcia, Peter H. Johnson, Vijay S. Kothare, Doris Weinstock (1999) Handbook of Diagnostic Tests. 2nd edition. Springhouse Corporation, Springhouse Pennsylvania. Carson, Maggie (2009) Assessment and management of patients with hypothyroidism. Nursing Standard. 23, 28, 48-56. Marieb, Elaine, N. and Katja Hoehn (2010) Human Anatomy & Physiology. 8th edition. Benjamin Cummings, San Francisco. Saladin, Kenneth S. (2010) Anatomy & Physiology The Unity of Form and Function. 5th edition. McGraw Hill, Boston. Tierney, Jr., Lawrence M., Stephen J. McPhee, Maxine A Papadakis (2000) Current Medical Diagnosis & Treatment. 39th edition. Lange Medical Books/McGraw-Hill, New York. Weinstock, Doris, Marcia Andrews, Jane V. Cray (1998) Professional Guide to Diseases. 6th edition. Springhouse Corporation, Springhouse, Pennsylvania.