1. 1QQ # 3 Name on top edge, back side of paper Answer on blank side of paper. 1.You’re called to the football field and asked to assist with a player who has stopped drilling on a hot humid summer day. How will you determine whether the athlete is experiencing heat exhaustion or heat stroke? What symptoms will you be looking for in each condition? 2.What type of drug would you take to control a fever? What is the mechanism of action of such drugs? Would you take that drug if your fever were 100 degrees Farenheit? Why or why not?

2. Fig. 16.01 =sink Absorptive Phase Hepatic Portal System Lipoprotein Lipase Once inside, glucose is converted to something else, thereby maintaining a concentration gradient for facilitated diffusion of glucose into cells.

3. 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-Portal Vessel- Capillary-Venule-Vein-Heart

4. Fig. 16.02 Post-absorptive phase Glucose Sparing Special case: Muscle wasting of starvation Note: Nervous tissue can use glucose and ketones Special term: Glycogenolysis & Gluconeogenesis

5. Major Points Absorptive phase lasts ~ 4 hours, cells “burn” glucose. During absorptive phase, energy needs provided by recently digested food During absorptive phase, excess is converted to stored fuel During post-absorptive phase, energy need met by release of stored fuels, most cells “burn” fatty acids, nervous tissue uses glucose and ketones. Fasting defined as greater than 12 hours after previous meal (some say 24 hrs) Fasting for several days has little effect on plasma glucose levels

6. The Issues How do cells “know” which fuel to “burn?” How do cells “know” when to synthesize glycogen or lipids and when to break down glycogen or lipid? What is responsible for the transitions from the absorptive and post-absorptive states? How does glucose get into “sink” cells?

7. Fig. 16.07 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?

8. Activates some enzymes, inactivates others: see next slide! 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

9. Stimulatory actions of insulin in green Inhibitory actions of insulin in dashed red

10. Absorptive Phase Post-Absorptive Phase

11. ? The Integrator integrates multiple inputs Glucose uptake, Storage, Lipogenesis WHY? FF Thinking about food Factors that influence Insulin Secretion

12. Another hormone that regulates plasma glucose concentration Glucagon prevails during post- absorptive phase Transition from absorptive to post- absorptive phase?

13. Graph your daily caloric intake over a 48 hour period 6am 6pm Noon MN Calories consumed 6am Noon Plasma Glucose 100 65 Overlay INSULIN SECRETION on the graph Overlay GLUCAGON SECRETION on the graph

14. Glucose-counterregulatory controls (oppose effects of insulin) Glucagon Epinephrine Cortisol (permissive effect) Growth hormone (permissive effect)

15. Fig. 16.10 EPI, yet another horomone in glucose homeostasis, effects opposite of Insulin Don’t fret about receptors, afferent pathway, and integrator for this feedback loop.

16. Who Cares?

17. A Case Study On our website at http://webs.wofford.edu/davisgr/bio342/oggt.htm A Case Study of Glucose Homeostasis A 35 year old male presented with the following complaints: frequent severe headaches upon awakening at 4:30 am, blurred vision, and fatigue due to excessive stress at work. The patient complained of routine 16 hr workdays followed by a midnight snack of breakfast cereal. An OGTT was ordered and provided the following results: During the second hour of the OGTT, the patient exhibited anxiety, paleness, hunger, tremulousness, and cold sweat. No additional tests were ordered. The patient was instructed to replace the midnight snack of cereal with a protein-rich snack.

18. Oral Glucose Tolerance Test Overnight fast, no beverages other than water Fasting blood sample Ingest 75 grams glucose Blood samples every 0.5 hours for 3-5 hours Plot plasma glucose concentration over time Compare curves Sugar content of Red Bull?

19. 60

20. Stress, Emergency (fight or flight), Exercise Effect on Beta cells Effect on Alpha Cells

21. The Answer to the Problem? Rationale for substituting protein for carbohydrate midnight snack?