Carbohydrate Metabolism 6

Mechanisms Hormonal Regulate Mechanisms Hormonal Regulate

The Concentration of the Blood GlucoseThe Concentration of the Blood Glucose

Source of blood glucose :Source of blood glucose :

-- Digestion and absorption of carbohydratesDigestion and absorption of carbohydrates

-- GlycogenolysisGlycogenolysis process process

-- GluconeogenesisGluconeogenesis process process

Several hormones play a part to maintenance of Several hormones play a part to maintenance of stable levels of glucose in the bloodstable levels of glucose in the blood

INSULIN INSULIN

-- Plays a central role in regulating blood glucosePlays a central role in regulating blood glucose

-- Secreted as a direct response to Secreted as a direct response to hyperglycemia hyperglycemia

-- Stimulation of glucose transport at the plasma Stimulation of glucose transport at the plasma membrane membrane

Mechanisms Hormonal Regulate Mechanisms Hormonal Regulate

The Concentration of the Blood GlucoseThe Concentration of the Blood Glucose

INSULIN INSULIN

-- Increase glucose utilization in a part by Increase glucose utilization in a part by promoting promoting glycogenesisglycogenesis

�� inhibiting inhibiting glycogenolysisglycogenolysis

�� cause lower of blood glucosecause lower of blood glucose

-- In the insulin/In the insulin/glucagonglucagon ratio is high , ratio is high , glycolysisglycolysisis predominates over is predominates over gluconeogenesisgluconeogenesis

GlucagonGlucagon

-- Activates Activates adenylyladenylyl cyclasecyclase to produce to produce cAMPcAMPwhich activates PKAwhich activates PKA

��phosphorylatesphosphorylates and activates and activates PyruvatePyruvate KinaseKinase

Mechanisms Hormonal Regulate Mechanisms Hormonal Regulate

The Concentration of the Blood GlucoseThe Concentration of the Blood Glucose

GlucagonGlucagon

�� activates of glycogen activates of glycogen phosphorylasephosphorylase and and inactivates of glycogen inactivates of glycogen synthasesynthase (increase (increase glycogenolysisglycogenolysis and decrease and decrease glycogenesisglycogenesis))

-- Inhibition of PFK 2, decrease the concentration Inhibition of PFK 2, decrease the concentration of fructose 2,6 of fructose 2,6 bisphosphatebisphosphate

-- Inhibition of PFK, activation of fructose 1,6 Inhibition of PFK, activation of fructose 1,6 bisphosphatasebisphosphatase

��decrease in the overall rate of decrease in the overall rate of glycolysisglycolysis and and increase in increase in gluconeogenesisgluconeogenesis

Mechanisms Hormonal Regulate Mechanisms Hormonal Regulate

The Concentration of the Blood GlucoseThe Concentration of the Blood Glucose

EpinephrineEpinephrine

-- Bind this hormone with Bind this hormone with ββ adrenergic receptors adrenergic receptors causes activation of causes activation of adenylyladenylyl cyclasecyclase

��increase increase cAMPcAMP ��activates PKA and activation activates PKA and activation of glycogen of glycogen phosphorylasephosphorylase ��increase increase glycogenolysisglycogenolysis

-- Skeletal lack glucose 6 Skeletal lack glucose 6 phosphatasephosphatase

��cAMPcAMP stimulates stimulates glycolysisglycolysis

GlucocorticoidsGlucocorticoids, GH, Thyroid hormone also , GH, Thyroid hormone also affecting the blood glucose affecting the blood glucose

Mechanisms Hormonal Regulate Mechanisms Hormonal Regulate

The Concentration of the Blood GlucoseThe Concentration of the Blood Glucose