BLOOD GLUCOSE REGULATION Flashcards
NORMAL BLOOD GLUCOSE LEVELS?
4-7.5 mmol/L
SOME HORMONES EXCEPT FOR GLUCAGON HAVE HYPERGLYCEMIC ACTION?
CORTISOL, GROWTH HORMONE, EPINEPHRINE
WHAT IS THE BODY’S LARGEST INSULIN SENSITIVE TISSUE?
SKELETAL MUSCLE
IS UPTAKE OF GLUCOSE BY THE BRAIN INSULIN DEPENDENT? WHY?
NO, IT’S NOT; THE BRAIN WILL TAKE UP GLUCOSE WHATEVER THE INSULIN SOURCES ARE BECAUSE IT IS ITS PRIMARY (ALMOST ONLY) SOURCE OF ENERGY
WHERE IS GLYCOGEN STORED IN THE BODY?
LIVER AND SKELETAL MUSCLE
WHICH GLYCOGEN STORES CAN BE MOBILIZED TO REGULATE BLOOD GLUCOSE DIRECTLY?
LIVER
LIVER GLYCOGEN STORES LAST FOR HOW LONG?
10-12 HRS (AN OVERNIGHT FAST)
EXAMPLES OF INSULIN ACTIONS BEYOND GLUCOSE REGULATION?
- STIMULATES PROTEIN SYNTHESIS
- FACILITATES VASODILATION
- STIMULATES K+ UPTAKE INTO CELLS
- STIMULATES Na+ REABSOPRTION IN RENAL TUBE
ACTIVATES LIPOGENESIS - INHIBITS FATTY ACID OXIDATION
- ACTS AS A GROWTH FACTOR AND HAS EFFECTS ON GENE EXPRESSION
- STIMULATES GLYCOGEN SYNTHESIS
DURING FASTING (EVEN JUST AN OVERNIGHT FAST) THE BRAIN CAN USE WHAT AS A SOURCE OF ENERGY INSTEAD OF GLUCOSE?
KETONE BODIES
HOW AND WHERE ARE KETONE BODIES FORMED?
IN THE LIVER THROUGH OXIDATION OF FATTY ACIDS WHICH ARE RELEASED FROM THE ADIPOSE TISSUE
IF THE BLOOD GLUCOSE LEVELS FALL BELOW WHICH POINT THE SIDE EFFECTS ARE CONVULSIONS, COMA AND DETAH?
1.5 mmol/L
COGNITIVE DYSFUNCTION (INCOORDINATION, ATYPICAL BEHAVIOUR, SPEECH DIFFICULTIES) START OCCURRING IF THE BLOOD LEVELS OF GLUCOSE FALL BELOW:
2.8 mmol/L
POSSIBLE CAUSES OF HYPOGLYCAEMIA?
- EXERTION/EXERCISE
- FASTING
- EXCESS EXOGENOUS INSULIN
- INSULINOMA
- ALCOHOL INTAKE (CAUSES INCREASE IN ENDOCRINE PANCREATIC MICROCIRCULATION, INCREASING INSULIN SECRETION + INHIBITS HEPATIC GLUCONEOGENESIS)
HOW DOES ALCOHOL INFLUENCE GLUCOSE LEVELS?
IT CAUSES INCREASE IN ENDOCRINE PANCREATIC MICROCIRCULATION, INCREASING INSULIN SECRETION + INHIBITS HEPATIC GLUCONEOGENESIS
5 MAIN COUNTER REGULATORY HORMONES TO INSULIN?
GLUCAGON, ADRENALINE, CORTISOL, GROWTH HORMONE, VASOPRESSIN
POSSIBLE CAUSES OF HYPERGLYCAEMIA?
STRESS (CHRONICALLY HIGH CORTISOL AND ADRENALINE)
INABILITY OF INSULIN TO INHIBIT GLUCONEOGENESIS
ABSOLUTE DEFICIENCY OF INSULIN (T1D; AUTOIMMUNE DESTRUCTION OF PANCREATIC BETA CELLS)
RELATIVE INSUFFICIENCY OF INSULIN (INSULIN RESISTANCE OF TISSUES)
WHAT IS INSULINOMA?
BENIGN TUMOUR CAUSING EXCESS ENDOGENOUS INSULIN
COMPLICATIONS ARISING FROM CHRONIC HYPERGLYCAEMIA (E.G. POORLY CONTROLLED DIABETES)?
- THE PROTEINS IN THE BLOOD GET CHEMICALLY MODIFIED BY THE HIGH GLUCOSE CONCENTRATIONS (ONE OF THEM IS HEAMOGLOBIN)
- SORBITOL PATHWAY IS OVER ACTIVE; SORBITOL IS A MONOSACCHARIDE AND IT AND THE FRUCTOSE FORMED FROM IT ARE OSMOTICALLY ACTIVE AND MAY DEPOSIT (ESP SEVERE IN THE LENS OF THE EYE)
- IMPAIRED VASODILATATION (DECREASE IN NITRIC OXIDE FORMATION)
- IMPAIRED REGULATION OF THE BLOOD FLOW TO THE EXTREMITIES + IMPAIRED NERVE FUNCTION RESULTING IN PERIPHERAL NEUROPATHY
WHAT ARE THE RESULTS OF INCREASED SORBITOL SYNTHESIS IN HYPERGLYCAEMIA?
- THE REDOX STATE INSIDE THE CELL IS DYSREGULATED (INCREASE IN THE FORMATION OF REACTIVE OXYGEN SPECIES WHICH ARE DELETERIOUS TO CELL FUNCTION
- SORBITOL AND FRUCTOSE FORMED FROM IT CAN DEPOSIT, ESP IN THE LENS OF THE EYE
WHAT HAPPENS WHEN THE ADIPOSE TISSUE BECOMES INSULIN RESISTANT?
THE LOSS OF ANTI-LYPOLITIC (INHIBITION OF TRIGLYCERIDE BREAKDOWN) EFFECTS OF INSULIN RESULTS IN THE INCREASED RELEASE OF FATTY ACIDS FROM ADIPOSE TISSUES + THE LIVER WILL CONTINUE TO SYNTHESISE AND SECRETE TRIGLYCERIDES WHICH FURTHER CONTRIBUTES TO HYPERLIPIDAEMIA