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 and Ch 16B.1 p 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 6am 6pm Noon MN Calories consumed 6am Noon Plasma Glucose ? ? Overlay absorptive and post-absorptive phases on the graph Phases: absorptive, post-absorptive, and fasting

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

Fig Absorptive Phase Lipoprotein Lipase Once inside, glucose is converted to something else, thereby maintaining a concentration gradient for facilitated diffusion of glucose into cells. =“sinks” Entry requires Glut-4 transporters

Activates some enzymes, inactivates others GLUT-4 Peptide hormone Exercise (via an undescribed mechanism) increases the number of glucose transporters in muscle cell membrane Diabetes mellitus: T1DM =beta cells fail to produce adequate insulin (5%) T2DM = target cells “resistant” (less responsive) to insulin ↑ plasma glucose →↑insulin secretion→↑glucose uptake into cells →↓ plasma glucose

Fig Identify sensors, afferent pathway, integrator, efferent pathway, effectors How is insulin secretion affected if plasma glucose is lower than set point? Which cell types have insulin receptors?

Islets of Langerhans Alpha cells secrete glucagon Beta cells secrete insulin Delta cells secrete somatostatin Route of blood Liver Typical vasculature: Artery-Arteriole-Capillary-Venule-Vein-Heart Hepatic portal system Artery-Arteriole-Capillary in digestive tract-Portal Vessel- Capillary in liver-Venule-Vein-Heart

? The Integrator integrates multiple inputs Glucose uptake, Storage, Lipogenesis WHY? FF Thinking about food, aroma, Factors that influence Insulin Secretion and other Incretins