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Help us decide who to hire as a Cell/Molecular Biology Lecturer Dr. Eva Ma will visit Wednesday January 20. Teaching presentation 2-3 pm, in DISC 464 (please come!) Dr. Alaron Lewis will visit Wednesday January 27. Teaching presentation 2-3 pm, in DISC 464 (please come!) Image: cargocollective.com/synapses/neurodevelopmental-biology-interview-michael-barresi BBio 351 – January 20, 2016 Outline for today: • The hypothalamic-pituitary axis (7.3) • • • • Anatomy, including pituitary parts Tropic hormones and feedback loops End-of-chapter questions Thyroid hormones (7.5) • Effects on metabolism • Rat experiments • Human disorders • Synthesis, storage, secretion Figures: A.D.A.M. & Anaesthetist.com What is “thyroid hormone”? Overall function of thyroid hormones: Effects on cellular metabolism: thyroid regulates Na+/K+ pump EXTRACELLULAR FLUID 3 Na+ Sodium– potassium exchange pump 2 K+ ATP ADP CYTOPLASM Martini Figure 3-19 (like Sherwood Figure 3-14) Effects on cellular metabolism: thyroid regulates non-shivering thermogenesis (NST) http://people.duke.edu/~sc9/pics/figure1.jpg (see also Sherwood Figure 15-19) What kinds of animals would benefit most from NST? Simulated rat experiments “PhysioEx” supplement to Marieb lab manual (2014) Simulated rat experiments • Part 1: Determining the basal metabolic rates (BMR) • 3 rats: normal, thyroidectomized, hypophysectomized • Thyroidectomy = • Hypophysectomy = • Measure BMR as O2 consumption rate (mL O2 per kg per hour) • O2 consumption is determined in a closed “metabolic chamber” • Part 2: The effect of thyroxine on metabolic rate • Treatment is applied for 1-2 weeks • Part 3: The effect of TSH on metabolic rate • Treatment is applied for 1-2 weeks • Part 4: The effect of propylthiouracil on metabolic rate • Propylthiouracil (PTU) is a drug that inhibits thyroxine production by blocking the attachment of iodine to tyrosine residues • Treatment is applied for 1-2 weeks “PhysioEx” supplement to Marieb lab manual (2014) Experimental outcomes Experiment Normal Thyroidectomized Hypophysectomized 1. Basal Metabolic Rate (BMR) “baseline” (1700 mL O2/kg/hr) ↑, ↔, ↓? ↑, ↔, ↓? 2. Thyroxine treatment ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) 3. TSH treatment ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) 4. PTU treatment ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) ↑, ↔, ↓? (vs. row 1) Thyroid disorders (overview) Category Causes Thyroid function diagnostic tests niddk.nih.gov Therapy for thyroid disorders? • Hypothyroidism • Hyperthyroidism Synthesis, storage, secretion of T3 & T4 Sherwood Figure 7-17 Synthesis, storage, secretion – key aspects • Thyroid follicle • Colloid • Thyroglobulin • Iodine Stimulation of thyroid gland by TSH • Review: where is TSH produced? • What kind of hormone is TSH? (polypeptide, amino acid derivative, steroid) • 3 key effects of TSH on thyroid follicular cells?