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Lab this Week Endocrinology of Hormone Supplementation Write a paragraph in which you 1) identify the major objectives of the paper (the most important questions it addresses), and 2) a concise summary of their most important findings. Bring this text with you to lab, ready to turn in to the lab instructor. Classes this Week • Glucose Homeostasis: Ch 16A p.555-567 and Ch 16B.1 p. 569-580 • Endocrinology Chapter 11 A-D, F 1QQ # 3 for 10:30 Name on top edge, back side of paper Answer on blank side of paper. 1. Describe what would happen if a person were injected with a drug that acts like Interleukin-6? 2. How can a feedforward response be distinguished from a negative feedback response? 3. What is the difference between heat stroke and heat exhaustion, and how can they be distinguished by physical examination? 4. How do Tylenol and other NSAIDs minimize a fever? 1QQ # 3 for 11:30 Name on top edge, back side of paper Answer on blank side of paper. 1. Describe what would happen if a person were injected with a drug that acts like Interleukin-6? 2. How can a feedforward response be distinguished from a negative feedback response? 3. What is the difference between heat stroke and heat exhaustion, and how can they be distinguished by physical examination? 4. How do Tylenol and other NSAIDs minimize a fever? Positive feedback • Examples of Positive Feedback in Physiology – – – – – Heat stroke (diagrammed earlier) formation of blood clot menstrual cycling of female sex hormone concentrations generation of action potentials in nerve fibers uterine contractions during childbirth • Each of these examples terminate naturally (self limiting) • Inherently unstable but some are essential for life! Glucose Homeostasis Another detailed example of negative feedback Graph your daily caloric intake over a 48 hour period Phases: absorptive, post-absorptive, and fasting Plasma Glucose Calories consumed ? ? 6am Noon 6pm MN 6am Noon 6pm MN 6am Noon Overlay absorptive and post-absorptive phases on the graph Homeostasis of Plasma Glucose Concentration • Why is too much plasma glucose harmful? • Plasma glucose concentration = glucose entering the plasma – glucose leaving the plasma • What are the mechanisms that regulate plasma glucose concentration? • What are the components of the negative feedback loop: – – – – – Glucose receptors? Afferent pathway? Integrator? Efferent pathway(s)? Effector organ(s)? Muscle Adipose Liver Nervous Other Absorptive Phase Fig. 16.01 Lipoprotein Lipase =“sinks” Entry requires Glut-4 transporters Once inside, glucose is converted to something else, thereby maintaining a concentration gradient for facilitated diffusion of glucose into cells. Exercise (via an undescribed mechanism) increases the number of glucose transporters in muscle cell membrane Peptide hormone GLUT-4 Activates some enzymes, inactivates others ↑ plasma glucose →↑insulin secretion→↑glucose uptake into cells →↓ plasma glucose Diabetes mellitus: T1DM =beta cells fail to produce adequate insulin (5%) T2DM = target cells “resistant” (less responsive) to insulin Identify sensors, afferent pathway, integrator, efferent pathway, effectors Fig. 16.07 How is insulin secretion affected if plasma glucose is lower than set point? Which cell types have insulin receptors? Liver Typical vasculature: Artery-Arteriole-Capillary-Venule-Vein-Heart Islets of Langerhans Alpha cells secrete glucagon Beta cells secrete insulin Delta cells secrete somatostatin Hepatic portal Route of blood system Artery-Arteriole-Capillary in digestive tract-Portal Vessel- Capillary in liver-Venule-Vein-Hea Factors that influence Insulin Secretion Thinking about food, aroma, ? and other Incretins WHY? The Integrator integrates multiple inputs FF Glucose uptake, Storage, Lipogenesis