exam 2

• what can store the largest total amount of glycogen in a human body?

  skeletal muscle
• • G6P can enter the pentose-phosphate pathway to produce R5P and/or NADPH
  • G6P can be dephosphorylated by G6P and the glucose formed is released into the circulation
  • G6P can be converted to pyruvate via glycolysis
• What is the relationship between the types of glucose transporter and the type of hexokinase in pancreatic beta cells?

  Low affinity GLUT2 transporter, low affinity Glucokinase
• Glucagon is a polypeptide
• what describes the changes in insulin and glucagon concentrations in the blood immediately after a meal compared to before the meal?

  insulin INCREASES, glucagon DECREASES
• what is the correct order of the four phases of starvation?

  glycogenolysis, gluconeogenesis, ketogenesis, terminal.
• GLP-1 is inactivated by Dipeptidyl peptidase-4 (DPP4) in blood

  • GLP-1 agonist are a type of therapy used to prolong GLP-1 stability and improve its rapid degradation by DPP4.
• Insulin signaling in the hypothalamus INHIBITS AMPK function and signals a FED state in the brain
• the [Insulin] INCREASES in the blood right after a meal
• the oral glucose tolerance test measures a person's ability to clear excess glucose from the circulation
• The [glucagon] in the blood DECREASES after a meal
• HbA1c measures the level of hemoglobin glycosylation of the HB beta chain N-terminal Val residue
• Metformin, Sitagliptin, Ozempic are used to treat type 2 diabetes.
• HIGH GLUCOSE :

  • INSULIN stimulates glucose uptake, glycogen synthesis, and FA synthesis, uptake and storage
• LOW GLUCOSE:
• GLUCAGON stimulates glycogenolysis, gluconeogenesis, lipolysis, ketone body production
• LOW GLUCOSE:

  • GLUCAGON stimulates glycogen mobilization, gluconeogenesis, glucose released into blood and FA mobilization
• PKA - protein kinase A - activated through GLUCAGON cascade - DEACTIVATES ACC (FA metabolism)/HMGR (cholesterol) with addition of phosphate group (uses ATP) - inactivates glycogen syntahse
• PP2A - priteins phosphatase 2A - activated through INSULIN cascade - ACTIVATES ACC (FA) / HMGR (cholesterol) with the REMOVAL of a phosphate group. Activates to make Malonyl-CoA (FA) to Mevalonate (Cholesterol).
• PP1 - protein phosphate 1 - activated through INSULIN cascade - INACTIVATES phosphorylase and CLEAVES a phosphate group
• LIVER -

  • GLUCAGON promotes glycogen breakdown, gluconeogenesis, and glucose export
  • promotes beta-oxidation and KB synthesis
• ADIPOSE TISSUE:

  • GLUCAGON promotes mobilization of FA so glucose is reserved for use by the brain
• PANCREAS:

  • GLUCAGON primarily targets Hepatic and Adipose tissues to signal the fasted state. Mobilizes fuels to spare glucose for the brain
• EPINEPHRINE increases heart rate, blood pressure, dilation of respiratory pathways
• LEPTIN inhibits AMPK - stopping food intake
• Ghrelin/Adiponectin signals to hypothalamus from AMPK of hunger
• glucose levels decrease w prolonged starvation
• ketone bodies greatly increase with further starvation
• phase 1 of starvation : GLYCOGENOLYTIC phase

  • only liver exports glucose
  • liver glycogen is rapidly depleted within 16-24h
• phase TWO of starvation : GLUCONEOGENIC phase

  • glycogen all depleted
  • only source of glucose bc FAs are unusable at this point
  • FAs cant be used to make glucose
  • FAs cant be used by the brain
  • ONLY SOURCE OF GLUCOSE IS --> GLUCONEOGENSIS
  • HOWEVER, proteins are being degraded TOO FAST
  • UNSUSTAINABLE
  • would only last 20-30 days
  • starts the shift to phase 3 - where the brain shifts to using KBs as fuel
• phase THREE of starvation : KETOGENETIC phase

  • rate of FA mobilization reaches its PEAK
  • KB production in liver increases
  • brain adapts to use ketone bodies
  • REDUCED GLUCOSE CONSUMPTION
  • REDUCED AMINO ACID BREAKDOWN
  • LAST RESORT FOR SURVIVAL
• phase FOUR of starvation : TERMINAL phase

  • run out of fat
  • start degrading massive amounts of protein
  • DEATH - no more sources of incoming metabolism
• Starvation in the midst of plenty - excess glucose not taken up, the body keeps telling you that you're still starved even when you eat
• Diabetes Mellitus - a lack of insulin function

  • glucose is not absorbed by tissues or reabsorbed by kidneys
  • glucose is excreted taking lots of H2O with it
  • urination is excessive, excess thirst
  • urine is sweet
• Oral glucose tolerance test - measures blood glucose before and every 30 mins after
• Hb-A1c test - measures the percent of hemoglobin that has been glycated with the open structure of glucose

  • higher percentage = more glucose being attached to hemoglobin
• TYPE ONE DIABETES

  • lack of pancreatic beta cells
  • NO PRODUCTION OF INSULIN
  • mern
  • cause - autoimmune disease that attacks pancreatic beta cells
  • responds to insulin injectionsan
• TYPE TWO DIABETES

  • non-insulin dependent diabetes mellitus
  • body becomes RESISTANT to insulin
  • insulin is present but doesn't produce the normal signals
• consequences of diabetes :

  • DAMAGE TO NERVES / BLOOD VESSELS : neuropathy, kidney disease, eye disease, risk of heart disease
  • gum disease and tooth decay
  • ketoacidosis - excess FA mobilized and excess KB produced (NOT GOOD)
• metformin - drug that inhibits gluconeogenesis in the LIVER and increases glucose uptake by muscle to combat type TWO diabetes