Control of blood glucose Flashcards
What is the function of glucose?
Energy source for most cells
Obligatory for energy in brain
More energy is made available in the diet than is required. How are excess calories stored?
Glycogen
Fat
How does digested food increase insulin secretion?
Increased amino acids, glucose and fatty acids in blood
Stimulates beta cells to secrete insulin
Where are insulin and glucagon produced?
Glucagon - alpha cells
Insulin - Beta cells
Of Islets of Langerhans in pancreas
Apart from increased AAs/fatty acids/glucose, how else can beta cells be stimulated to produce insulin?
Parasympathetic NS (sympathetic decreases secretion of insulin) GI hormones (GIP, GLP-1)
Insulin affects what 3 parts of the body?
LAM
Liver
Adipose tissue
Muscle
Are insulin and glucagon anabolic or catabolic?
Insulin - catabolic
Glucagon - anabolic
How does insulin affect the liver?
Inhibits glyocgenolysis and gluconeogensis
How does insulin affect adipose tissue?
Stimulates up regulation of GLUT4 and glucose
Increases carbohydrate and fat metabolism
How does insulin affect muscle?
Upregulates expression of GLUT 4 (glucose transporter)
Increases glucose uptake
Stimulates glycolysis and glycogen synthesis
What is the obligatory source of fuel for the brain? What cells in the brain are NOT sensitive to insulin? How does CSF relate to blood sugar?
Glucose
Neurons
CSF glucose concentration directly proportional to blood glucose
What stimulates glucagon secretion?
Low concentrations of glucose and fatty acids in plasma
High concentration of amino acids
What inhibits glucagon secretion?
High concentrations of glucose and fatty acids in plasma
How does glucagon increase blood glucose?
Stimulates breakdown of fat and proteins
Stimulates glycogenolysis, gluconeogenesis
Inhibits glycogen synthesis
What receptor does glucagon have similar effects to? What effect does glucagon have on the heart?
Beta adrenoreceptors
Increases contraction of heart (but metabolic effects much greater)
Which hormones (apart from glucagon) increase blood glucose concentration?
Adrenaline
Glucocorticoids
Growth hormone
Diabetes mellitus is a chronic metabolic disorder causing hyperglycaemia. What are the 2 types of diabetes? Which is more common in cats and dogs?
Type 1 - insulin dependent - lack being produced by pancreas (dog)
Type 2 - non-insulin dependent - reduced sensitivity to insulin (cat)
How can diabetes be diagnosed?
History, clinical signs
Fasting hyperglycaemia
Insulin resistance (hyperglycaemia not responsive to exogenous insulin, type 2)
What 2 drugs can be used to treat diabetes mellitus?
Insulin replacement drugs or insulin receptor agonists
Oral hypoglycaemics
Insulin is identical in which species? In which species is insulin very similar?
Pigs and dogs = identical
Cats and cows = very similar
How do insulin replacement drugs/agonists work?
Bind to insulin receptor on cell surface
Increase glucose uptake, glycogen synthesis
Decrease gluconeogenesis and glycogenolysis
How are insulin replacement drugs/agonists given?
Usually subcut
Can be given IV in emergency
Not orally as peptides broken down in stomach
When might insulin replacement drugs/agonists be given?
Type 1 diabetes
Hyperglycaemic emergencies (IV)
Emergency treatment of hyperkalaemia
What are the adverse effects of insulin replacement drugs/agonists?
Hypogylcaemia - give IV glucose
Insulin resistance
