BIO 311D 2nd Edition Lecture 24 Outline of Last Lecture I. Homeostasis and negative feedback controlII. How do hormone systems work?III. Homeostasis of blood glucose levelOutline of Current Lecture I. Diabetes Mellitus II. Hypothalamus and pituitary controlIII. Feedback control of thyroid functionIV. The adrenal glands- two part response to stressCurrent LectureI. Diabetes Mellitus A. Type I: insufficient insulinB. Type II: can’t respond to insulin C. IClicker Questions - When blood glucose levels drop below the set level, which of these is triggered? – Glucagon is secreted - One cause of juvenile-onset diabetes results from autoimmune attack anddestruction of the beta cells of the pancreas. Which type of diabetes would result? – Type I Treated? – Insulin injections - Type II Diabetes is treated by: exercise, diet II. Hypothalamus and pituitary controlA. The hypothalamus is part of the brain that monitors body conditions. Part of the hypothalamus consists of neuro-secretory cells [secrete directly into blood]. Neurosecretory cell secretes releasing factor. B. The pituitary is an endocrine gland in the center of the head. The anterior pituitary gland secretes tropic hormones. C. Hypothalamus: release hormones such as TRH (thyrotropin-releasing hormone)D. Neurohormones from hypothalamus travel in the blood and affect the pituitary gland. E. Anterior pituitary: Tropins- TSH ACTH. & Gonadotropins: affect other glandsIII. Feedback Control of Thyroid FunctionA. Thyroxin: travels in blood complexes with glucose B. In order for the negative feedback to work, the anterior pituitary would need to have receptors for T3/ T4. C. Cool body temperature stimulates hypothalamus to release more TRH. How? Hypothalamus: sensors detect changes in temperature in the blood in the capillaries in the brain – activates the thyroid to release thyroxin D. High Levels of TSH cause hypothalamus to release less TRH. How?A classic negative feedback: TSH can be monitored by hypothalamus E. High T3&T4 stimulate metabolism and produce more body heat? How could the heat activate negative feedback control F. A hyperactive thyroid can lead to slightly elevated body temperature G. Goiter: enlarged thyroid gland. Iodine is required for making thyroxin (T3 and T4).People with iodine-deficient diet can develop goiter. Can’t produce thyroxin so just grow biggerIV. The Adrenal Glands (attach on kidney, stress responses)A. The adrenal cortex produces steroid hormones (glucocorticoids, mineralocorticoids, and sex steroids): respond to hormones, pituitary gland Corticosteroid (steroid) target cell receptor locates inside the cell receptor. Long response B. The adrenal medulla produces epinephrine and norepinephrine, gets it signals from the nervous system.Epinephrine (peptide) target cell receptor in plasma membrane, triggers signal transduction. Short
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