Carbohydrate metabolism and control of blood glucose Flashcards
how is glucose transported across the cell membrane
facilitated diffusion
glucose binds to the receptor carrier protien
creates a conformational change
intracellular release
how is GI glucose absorption brought about
linked to active sodium -glucose co- transport
Where is insulin produced
Pancreatic beta cells in the islets of langerhans
When is insulin secreted
When blood sugars are high
What is the half life of insulin
6 mins
How is insulin degraded
by insulinase in the liver
What is the mechanism of insulin secretion
-increase in glucose - glucsose taken into beta-cell by faciliated diffusion
- glucose converted to glucose-6-phophate by glucokinase
G6P oxidised to ATP
k+ channels open and K+ enter cell- depolarises
Depolarisation causes Ca2+ channel to open and influx of Ca2+
Insulin stored in vesicles exit the cell by exocytosis
impact of somatostatin/norepinephrine on insulin
Reduced insulin secretion
Impact of glucagon-like-peptide-1 on insulin
Promotes ca2+ influx and therefore promote the release of insulin
Sulphonylurea drug impact on insulin
Encourage K+ channels to close
What impact does sympathetic stimulation and epinephrine have on insulin
decrease insulin secretion
What else has an influence on insulin
Amino acids
GI hormones
Autonomic nervous system
What tissues are metabolic targets
Adipose
Straited muscle
Liver
What will an incease in insulin cause
Glucokinase - Glucose -6- PO4- glucose uptake
glycogen synthase - Glycogen storage
ALL INCREASE
What will a decrease in insulin cause
increase in
liver pohosphorylase causes increasein glycogen breakdown
increase in phsophatease would a decrease in glucose-6-PO4 which would cause an increase in glucose release
What impact does insulin have on the brain
Insulin does not effect glucose uptake in the brain
What is insulin converted by
glucagon
adrenaline/noradrenaline
cortisol
growth hormone
Where is glucagon produced
Pancreatic alpha cells in islets of langerhans
When is glucagon secreted
When blood glucose in low
What does glucagon promote
Hepatic glucose release which increases glucogenolysis
What does an increase in glucogenolysis cause
An increase in liver phosphorylase casuing an increase in glycogen breakdown and an increase in glucose release
When does gluconeogenesis start to occur
When all the glycogen stores have been depleted
Features of Type 1 diabetic
Insulin dependent
beta cell dysfucntion
juvenile onset
Features of type 2 diabetic
Non - insulin dependent
Insulin resistance
obesity related
> 30 years old
