hormonal reglation of blood glucose levels
TRANSCRIPT
GLUCOSE HOMOESTASISRegulation of blood glucose levels
DR ROHINI C SANE
PROFESSOR
DEPARTMENT OF BIOCHEMISTRY
DR D Y PATIL MEDICAL COLLEGE
EBENE
Normal values of serum glucose & clinical significance
• Status Physiological levels Diabetes Mellitus
FASTING ˂ 110 MG/DL(˂ 6.1 mmol/lt)
˃ 126 mg/dl (˃ 7 mmols/lt)
1 hr (peak ) after glucose intake
˂ 160 MG/DL(˂ 9.0 mmol/lt)
Not described
2hrs (after glucose ) ˂ 140 MG/DL(˂ 6.1 mmol/lt)
˃ 200 mg/dl (˃11.1 mmols/lt)
Hypoglycemia
• Blood glucose < 45 mg/dl----life threatening ---unconscious ---irreversible brain damage --death
Symptoms
• Head ache
• Anxiety
• Confusion
• Sweating
• Slurred speech
• Seizures
• Coma
• Death
HypoglycemiaCauses
• Insulin over dose (intensive regimes )
• Post pandrial -increase insulin-- >transient hypoglycemia-->mild symptoms
• Pancreatic beta cell tumor-insulin secreting tumor (liver cell dmage—>Hepatocellular damage)
• Alcohol treatment
• hypo secretion of adrenal /pituitary /thyroid hormones
• Drug /dyes induced liver damage
Oxidative pathways of glucose –decreasing glucose levels
• Normal fasting blood glucose ---70-110mg%(4.5—5.5mg%)
• Glycolysis
• HMP shunt
• Uronic acid pathway
Synthetic pathways of glucose –Decreasing glucose levels
• fructose ,Galactose, lactose ,maltose ,sucrose &mucopolysaccharidessynthesis
• Glycogenesis
• Lipogenesis
• Synthesis of non essential amino acids
Sources of glucose in human body
• Absorption of Dietary carbohydrates in GIT (starch /sucrose /glucose/Fructose/ lactose /maltose)
• Gluconeogenesis (amino acids /glycerol /propionate/lactate/pyruvate )
• Glycogenolysis in liver & muscles
Depletion of glucose in human body
• Glycolysis—TCA (for energy purpose)
• GLYCOGENESIS
• SYNTHESIS OF AMINO SUGARS /MONOSACCHARIDES
• SYNTHESIS OF FAT
• HMP SHUNT
• RENAL EXCRETION---RENAL THRESHHOLD ---180MG%
• RENAL TUBULAR MAXIMA FOR GLUCOSE---(TMG)---360 MG%
GLUCOSE HOMEOSTASIS• DEFINITION ---REGULATION OF BLOOD GLUCOSE IN NORMAL RANGE
• NORMAL FASTING BOOD GLUCOSE LEVELS (70—110MG/DL) NORMAL POST PANDRIAL BOOD GLUCOSE LEVELS (110—180MG/DL)
GLUCOSE HOMEOSTASISTWO MECHNISMS OF REGULATION OF BLOOD GLUCOSE
• I HORMONAL REGULATION
HYPERGLYCEMIC HORMONES (MANY )
ONLY HYPOGLYCEMIC HORMONE---- INSULIN
• II ALIMENTARY MECHANISM
Role of stomatch
Role of liver
Role of muscles
Role of kidey
I HORMONAL REGULATION- HYPOGLYCEMIC HORMONE---INSULININCREASES UTILIZATION OF GLUCOSE THROUGH
GLUCOSE UPTAKE
GLYCOLYSIS
GLYCOGENESIS
HMP SHUNT
LIPID SYNTHESIS
DECREASES SYNTHESIS OF GLUCOSE VIA
• GLUCONEOGENESIS
• GLYCOGENOLYSIS
• TREATMENT OF DM ---TOLBUTAMIDE INDUCES INSULIN SECRETION BY BETA PANCREATIC CELLS
I HORMONAL REGULATIONHYPERGLYCEMIC HORMONES(Anti- insulin hormones )
• GLUCAGON(ALPHA cells of islets of langerhans )
• EPINEPHRINE (Adrenal medulla ---under stress conditions )
• THYROXINE (thyroid gland)
• GLUCOCORTICOIDES (adrenal cortex )
• GROWTH HORMONES
• ACTH
I HORMONAL REGULATION- HYPERGLYCEMIC HORMONES
INCREASE GLUCOSE LEVELS BY ENHANCING• GLUCONEOGENESIS• GLYCOGENOLYSIS• ALIMENTARTY ABSORPTION DECREASES UTILIZATION OF GLUCOSE BY DECREASINGGLUCOSE UPTAKEGLYCOLYSISGLYCOGENESISHMP SHUNTLIPID SYNTHESIS
REGULATION OF BLOOD GLUCOSE LEVELS
EFFICIENT
• TO MAINTAIN CONTINUOUS SUPPLY TO BRAIN WHICH HAS OBLIGATORY REQUIREMENT FOR GLUCOSE
• RBC ,RENAL MEDULLA OR CELLS LACKING MITOCHONDRIA NEEDS GLUCOSE AS ENERGY SOURCE
• WELL FED CONDITION –BLOOD GLUCOSE LEVELS HIGH ---INSULIN INCREASES & HYPER GLYCEMIC HORMONES DECREASE (I/G INCREASES)
• STARVATION--- BLOOD GLUCOSE LEVELS LOW-- INSULIN DECREASES & HYPERVGLYCEMIC HORMONES INCREASE IN CIRCULATION (I/GDECREASES)
I ALIMENTARY MECHANISM-STOMATCH
HIGH GLUCOSE LEVELS - WELL FED LOW GLUCOSE LEVELS -STARVATION
DISTENTION OF STOMATCH
SLOW EMPTYING
SLOW ABSORPTION IN GIT
INCREASED ABSORPTION IN GIT
II ALIMENTARY MECHANISM-LIVERHIGH GLUCOSE LEVELS - WELL FED LOW GLUCOSE LEVELS -STARVATION
UTILIZATION OF GLUCOSE INCREASESGLYCOGEN SYNTHESIS INCREASES
GLYCOGENOLYSIS DECREASES
LIPOGENESIS INCREASES
GLUCONEOGENES INCREASES
GLYCOGENOLYSIS INCREASES
GLUCOSE UTILIZATION DECREASE
LACTIC /CORI CYCLE (CONVERSION OF LACTOSE TO PYRUVATE--GLUCOSE INCREASES)
III ALIMENTARY MECHANISM-MUSCLES HIGH GLUCOSE LEVELS- WELL FED LOW GLUCOSE LEVELS STARVATION
UTILIZATION OF GLUCOSE INCREASESGLYCOGEN SYNTHESIS INCREASES
GLYCOGENOLYSIS DECREASES
LLIPOGENESIS INCREASES
GLYCOGENOLYSIS INCREASES
GLUCOSE UTILIZATION DECREASE
IV ALIMENTARY MECHANISM-KIDNEY
HIGH GLUCOSE LEVELS - WELL FED LOW GLUCOSE LEVELS-STARVATION
HYPERGLYCEMIA ---GLYCOSURIA COMPLETE REABSORPTION OF GLUCOSE BY RENAL TUBULAR CELLS
RENAL THRESHOLD –180 MG/DL TMG -360 MG/DL