Glucose regulation pancreas liver


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Glucose regulation pancreas liver

  1. 1. Glucose Regulation <ul><li>What is diabetes? </li></ul><ul><li>Cells need sugar—ATP and the Krebs Cycle </li></ul><ul><li>What comes in through the gut—basic nutrition </li></ul><ul><li>Role of liver in processing nutrients, storing glucose </li></ul><ul><li>Absorptive Pathways and role of insulin from pancreas </li></ul><ul><li>Post-absorptive Pathways </li></ul><ul><li>Understanding Diabetes </li></ul>
  2. 2. Diabetes mellitus—”starvation amidst plenty” <ul><li>Type I </li></ul><ul><ul><li>Juvenile onset </li></ul></ul><ul><ul><li>Pancreas beta cells die, no insulin produced </li></ul></ul><ul><li>Type II </li></ul><ul><ul><li>Adult onset </li></ul></ul><ul><ul><li>Complicated set of factors, some insulin production </li></ul></ul><ul><li>Goal—understand why we need insulin </li></ul>
  3. 3. Cells and Glucose <ul><li>All cells of body need constant glucose supply, especially nervous tissue </li></ul><ul><li>Most other nutrients can be converted into glucose or derivatives for making ATP </li></ul><ul><li>ATP is celluar “gasoline” </li></ul>
  4. 4. Glycolysis and Kreb’s Cycle <ul><li>Main way that cells make ATP </li></ul><ul><li>Glucose is principle reactant </li></ul>
  5. 7. Why not eat just sugar?
  6. 8. Essential Amino Acids <ul><li>Only additional nutrients that body can’t produce </li></ul><ul><li>Needed for making proteins </li></ul><ul><li>Also some vitamins and minerals must come from diet </li></ul>
  7. 9. What happens to the rest of what we eat?
  8. 10. Interconversion of Nutrients <ul><li>Almost everything we eat can be converted and used by Kreb’s cycle </li></ul>
  9. 11. <ul><li>We need some other nutrients—essential amino acids, vitamins, minerals </li></ul><ul><li>Our body also uses fats and proteins directly from diet </li></ul>Why not eat just sugar?
  10. 12. What keeps sugar constantly available in blood? <ul><li>Immediately after a meal, nutrients are flowing into blood across wall of stomach, small intestines </li></ul><ul><li>Between meals, when food has mostly been digested, nutrients are not available </li></ul><ul><li>Nonetheless, blood sugar levels are kept virtually constant </li></ul><ul><li>How is this possible? </li></ul><ul><ul><li>Role of liver in temporary storage of glucose as glycogen </li></ul></ul><ul><ul><li>Differences in “absorptive” and “post-absorptive” metabolic pathways </li></ul></ul>
  11. 13. Liver <ul><li>STRUCTURE </li></ul><ul><ul><li>Large ventral organ of abdominal cavity with multiple lobes (learn them!!) </li></ul></ul><ul><ul><li>Sets against inferior surface of diaphragm on left side </li></ul></ul><ul><ul><li>Forms as outpocketing of gut--common bile duct is left as connection </li></ul></ul><ul><ul><li>Bile duct is two-way street (bile from hepatic duct is stored in gall bladder and later expelled to common bile duct to duodenum) </li></ul></ul><ul><li>FUNCTION </li></ul><ul><ul><li>Digestion--bile is digestive enzymes plus RBC breakdown product </li></ul></ul><ul><ul><li>Removes nutrients and toxins from blood (hepatic portal system brings gut blood directly to liver) </li></ul></ul><ul><ul><li>Glucose metabolism (with pancreas--see below) </li></ul></ul>
  12. 14. General blood supply to gut--ventral branches off of aorta <ul><li>Celiac a.--to stomach, liver, pancreas, spleen, duodenum </li></ul><ul><li>Superior (cranial mesenteric a.--to small intestines and most of colon </li></ul><ul><li>Inferior (caudal) mesenteric a.--to descending colon, rectum </li></ul>
  13. 15. Liver: Blood Supply <ul><li>Hepatic Vein </li></ul><ul><ul><li>from inferior vena cava </li></ul></ul><ul><li>Hepatic Artery </li></ul><ul><ul><li>from abdominal aorta </li></ul></ul><ul><li>Hepatic Portal Vein </li></ul><ul><ul><li>Carries nutrient-rich blood from stomach + intestines to liver </li></ul></ul><ul><ul><li>Portal system = 2 capillary beds! </li></ul></ul>pg 660
  14. 16. Hepatic Portal System--anatomy
  15. 17. Hepatic Portal System--concept <ul><li>Directs blood that has already been through gut capillaries into liver capillaries (or sinusoids) </li></ul><ul><li>Allows nutrients and toxins to be removed from blood </li></ul>Fig. 19.22, M&M
  16. 18. How does liver work? <ul><li>Blood from portal vein and hepatic artery enter into central vein of liver lobules </li></ul><ul><li>Leaky capillaries called sinusoids then bring blood into contact with hepatocytes or liver cells </li></ul>
  17. 19. Liver function <ul><li>Versatile hepatocytes do the following: </li></ul><ul><ul><li>Process nutrients including storage of glucose </li></ul></ul><ul><ul><li>Store fat-soluble vitamins for later use by body </li></ul></ul><ul><ul><li>Detoxification of blood </li></ul></ul><ul><li>Other macrophage-like Kupffer cells also remove debris such as worn-out RBC’s </li></ul>
  18. 20. Following a meal, with nutrients flowing into blood from gut
  19. 21. Role of insulin in take-up of glucose (from pancreas beta cells) by cells during absorptive state
  20. 22. Between meals, with no nutrients flowing into blood from gut
  21. 23. <ul><li>Role of glucagon (from pancreas alpha cells) in release of glucose by cells during post-absorptive state </li></ul>
  22. 24. Pancreas <ul><li>STRUCTURE </li></ul><ul><ul><li>Smaller, diffuse gland </li></ul></ul><ul><ul><li>Head in C of duodenum </li></ul></ul><ul><ul><li>Tail extends towards spleen </li></ul></ul><ul><li>FUNCTION </li></ul><ul><ul><li>Digestion--produces most digestive enzymes </li></ul></ul><ul><ul><li>Glucose metabolism--Islets of Langerhans </li></ul></ul><ul><ul><ul><li>Beta cells make insulin </li></ul></ul></ul><ul><ul><ul><li>Alpha cells make glucagon </li></ul></ul></ul>
  23. 25. “ How Stuff Works” Diabetes:
  24. 26. Glucose metabolism <ul><li>Liver receives blood from intestines (don’t forget hepatic portal system </li></ul><ul><li>After meal, in response to insulin from pancreas, glucose stored as complex carbohydrate--glycogen--in liver </li></ul><ul><li>Between meals, in response to glucagon from pancreas, glucose is released </li></ul><ul><li>Pancreas releases insulin when sugar levels in blood go up </li></ul><ul><li>Inadequate or zero insulin production results in hyperglycemia or high blood sugar </li></ul><ul><li>Overproduction or over-dosing of insulin results in hypoglycemia or low blood sugar--insulin shock </li></ul><ul><li>Diabetes is insufficient production of insulin </li></ul><ul><ul><li>Type I--juvenile onset with elimination of Islets of langerhans and zero insulin production </li></ul></ul><ul><ul><li>Type II--adult onset with gradual loss of insulin production </li></ul></ul>