Integration Flashcards
Example of Regulation via Compartmentation
pyruvate in cytoplasm –> lactate or alanine while in mito –> acetyl Coa –> TCA cycle
5 Phases of Glucose Homeostasis
- I- FED- blood glucose is from diet; all tissues use glucose
- II- FAST- start to replenish blood glucose via glycogen mobilization; all tissues still use glucose except liver
- III- FAST 24 HR- supplement w/ hepatic gluconeogenesis; still all tissues use glucose except liver
- IV- FAST 2 DAYS- no more glycogen and kidney starts to contribute to gluconeogenesis too; brain starts to use ketone bodies; glucose only used by brain/RBC and some muscle
- V- FAST 1 MONTH- only brain and RBC using glucose; brain uses more ketones than glucose
2 Features of Starvation
- Protein sparing - muscles will start to degrade protein –> AAs as fuel; to prevent this…ketones formed in liver to be used as energy in muscle instead
- Metabolic acidosis - leads to cation loss in urine; overcome in kidney by using glutamine –> NH4+ and bicarb (the bicarb acts as a buffer for acidosis and NH4+ can now be excreted instead of cations)
6 Metabolic Paths of Carbs
- 1- glycogen synthesis
- 2- glycogen mobilization
- 3- glycolysis
- 4- gluconeogenesis
- 5- pentose phosphate shunt (aka hexose monophosphate shunt)
- 6- TCA (Krebs) cycle
Which processes dispose of glucose? Which are oxidative v non-oxidative?
- Oxidative…TCA cycle, PPP
- Non-oxidative… glycogen synthesis, glycolysis
Effects of insulin on liver
- Reduces hepatic glucose output
- Inc glycogen synthesis (activate glycogen synthase)
- Inc glycolysis (activate PFK and pyruvate kinase)
- Suppress glycogen mobilization (inhibit phosphorylase kinase - so glycogen phosphorylase not active)
- Suppress gluconeogenesis (inhibit pyruvate carboxylase, PEPck and fructose 1,6 bisphosphate
**intermediate sensitivity
Effects of insulin on fat
- Stim glucose uptake
- Recruit glucose transporters to cell surface (bind insulin receptors –> phos cascade)
- Stim TG synthesis
- Stim glycolysis –> pyruvate + glycerol
- Produce NADPH through PPP
- Activate FFA synthase
**Most sensitive
Effects of insulin on skeletal muscle
- Stim glucose uptake
- Recruit glucose transporters to cell surface (bind insulin receptors –> phos cascade)
- Stim glycogen synthesis
**least sensitive
Which hormone suppress and stimulate hepatic glucose production?
Stimulate
- Epinephrine, glucagon, cortisol, GH
- All stim by falling plasma glucose levels ("counter-regulatory hormones")
Suppress
- Insulin
Classic Symptoms of Hyperglycemia (6)
- Polyuria (frequent urination)
- Nocturia (getting up frequently at night to pee)
- Polydipsia (excessive thirst stim by excessive urination)
- Weight loss (from loss of glucose/calories in urine)
- Yeast infections in female urogenital tract (yeast likes the sugar)
- Polyphagia (excessive appetite)
Type 1 v Type 2 Diabetes
Type 1- lean, islet cell antibodies, insulin secretion absent, no insulin resistance, beta cells do not function
Type 2- fat, no islet cell antibodies, insulin secretion present but not enough, insulin resistance, beta cells functioning but not enough
Diabetic Ketoacidosis
- Only in type I
- Acute, life threatening episode
- Complete absence of insulin + excess glucagon –> generation of keto-acids
- How? Accelerated lipolysis –> free FAs to liver; more FAs taken up by liver mito –> beta oxidation + accumulation of acetyl CoA –> acetyl CoA then used in ketone formation (also in liver mito)
How to treat type 1 diabetes
use insulin right from start; not oral agents
How to treat type 2 diabetes (5)
Hepatic insulin sensitizers
- Inc efficacy of insulin in liver - biguanides
Peripheral insulin sensitizers
- Inc efficacy of insulin in glucose uptake in skeletal muscle - TZDs
Insulin secretagogues
- Stim secretion of insulin from beta cells - Sulfonylureas & meglitnides
Alpha glucosidase inhibitors (AGIs)
- Inhibit enzymes in gut that are responsible for carb digestion; so slows down absorption of carbs from gut
Insulin - After years
Primary Complications of Type 2 Diabetes
Non-enzymatic glycosylation of proteins (leads to AGE formation in vessels after long time) AND form HbA1c in RBCs (not alive long enough to form AGE)
Activation of polyol pathway - converted to sorbitol via aldol reductase (retinopathy, cataracts, Schwann cell damage –> neuropathy)
Treating Classical v Atypical PKU
- Classic- low PHE diet w/ protein supplements
- Atypical- give BH4 supplement
PKU Inheritance and Incidence
- Auto recessive
- Incidence is 1/10,000 (most common error of inborn metabolism)
